- Email: [email protected]
Braid configuration designed for fiber-packed capillary in microscale sample preparation
Journal Pre-proof
Braid Configuration Designed for Fiber-Packed Capillary in Microscale Sample Preparation Koki Nakagami , Tomoya Monobe , Ohjiro Sumiya , Kazunori Takashima , Ikuo Ueta , Yoshihiro Saito PII: DOI: Reference:
S0021-9673(19)31123-9 https://doi.org/10.1016/j.chroma.2019.460694 CHROMA 460694
To appear in:
Journal of Chromatography A
Received date: Revised date: Accepted date:
2 August 2019 7 November 2019 7 November 2019
Please cite this article as: Koki Nakagami , Tomoya Monobe , Ohjiro Sumiya , Kazunori Takashima , Ikuo Ueta , Yoshihiro Saito , Braid Configuration Designed for Fiber-Packed Capillary in Microscale Sample Preparation, Journal of Chromatography A (2019), doi: https://doi.org/10.1016/j.chroma.2019.460694
This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2019 Published by Elsevier B.V.
Highlights
Miniaturized sample preparation with braid-type extraction medium was developed.
The extraction capillary was prepared using the braid with a metal wire inside.
Applying low voltages to the metal wire, a heat-assisted desorption was made.
1
Braid Configuration Designed for Fiber-Packed Capillary in Microscale Sample Preparation Koki Nakagami1, Tomoya Monobe1, Ohjiro Sumiya1, Kazunori Takashima1, Ikuo Ueta2 and Yoshihiro Saito1,* 1Department
of Applied Chemistry and Life Science, Toyohashi University of Technology,
Toyohashi 441-8580, Japan 2Department
of Applied Chemistry, University of Yamanashi, Kofu 400-8511, Japan
*Corresponding Author at: Department of Applied Chemistry and Life Science, Toyohashi University of Technology, Toyohashi 441-8580, Japan. E-mail address: [email protected] (Y. Saito)
2
Abstract A novel miniaturized sample preparation device with braid-type extraction medium was successfully developed. Introducing a set of bundles of fine synthetic filaments as the materials of the braid-type extraction medium and also the application of an appropriate tension during the braiding process, the outer diameter of the resulting braid has been controlled. Optimization of the tension enables an easy preparation of a group of braids that can be well-compatible to various internal diameters of capillaries to be packed.
The extraction conditions were systematically optimized, and the
efficient extraction was confirmed under the optimized conditions. All the parameters affects the desorption efficiency were also optimized, where typical extraction efficiency was more than 90% for the extraction of phenanthrene (1.0 μg/mL) in water. The extracted analyte was desorbed sufficiently by employing a sequential pumping process of two organic solvents. During the preparation of the braid, a different type of fibrous materials could be inserted to the opening at the center of the braid. Taking advantage of this feature of the braid, a stainless steel wire was inserted into the center of the braid. By applying low voltages to the stainless steel wire, a heat-assisted desorption of the extracted analyte was also studied.
Experimentally complete
desorption (higher than 99.0%) was obtained with the voltage application of 2V. The lowest limit of quantification (LOQ) and the lowest limit of detection (LOD) for phenanthrene were 0.048 and 0.014 μg/mL, respectively. Keywords: Braid; Synthetic fiber; Sample preparation; Solid phase extraction; Thermal desorption
3
1. Introduction Braid is one of the most popular Japanese traditional craft, and it has been employed as a part of accessories since ancient times [1]. Typical braid is consisted of a set of fiber bundles. Because of the excellent mechanical strength and flexibility, there are many types of the industrial applications such as, rope and flexible high pressure tubing. Changing the tension during the braiding preparation, the outer diameter could be reproducibly controlled, which enables an easy preparation of a group of braids compatible to be inserted into various sizes of capillaries. In addition, typical braid has an open channel in the center. This is another advantageous feature of the braid, and therefore, a different type of fibrous materials can be successfully inserted into the center opening, suggesting a possibility to the development of novel hybrid materials for a sample preparation device in separation science. Liquid chromatography (LC) and gas chromatography (GC) have been regarded as strong tools for the analysis of various complex sample matrices. However, the analyst still needs an appropriate sample preparation in most cases, due to a low concentration of the target compounds and the complexity of the sample matrices. Extraction is one of the most fundamental sample preparation techniques to concentrate the target compounds in a typical complex sample matrix. In the extraction methods conventionally employed, liquid-liquid extraction, has been widely used [2-4], however, the method has several disadvantages such as sample loss during manual handling and a large volume consumption of organic solvents. Solid phase extraction (SPE) has been recognized as an alternative method because of its small organic solvent consumption and an easy operation [5,6]. As one of the approach to the down-sizing of the sample preparation and the subsequent chromatographic separations in the past decades, various types of synthetic fibrous materials have been introduced in separation science due to the excellent resistance to high temperature and organic solvents [7-9], where these fibrous materials are employed as the extraction medium in
4
sample preparation device [10-19] and the stationary phase in chromatographic separations [20-26]. Various synthetic fibers, as typically mentioned above, were successfully introduced as a SPE medium for the preconcentration and derivatization of target analytes in aqueous and air matrices [27-31]. In these applications, a bundle of fine filaments was packed longitudinally into a capillary to prepare the miniaturized extraction cartridges for the sample preparation and the columns for chromatographic separations. Compared with conventional solid-phase microextraction (SPME) and SPE using particle-packed cartridges [32,33], these fine-filaments-packed capillaries could have additional advantages such as easy on-line coupling to various chromatographic techniques.
Taking advantage of the feature of the easy on-line coupling of the
extraction method to the separation system, the extraction capillary could be further applied to a modulator in multi-dimensional separations.
Although typical liquid
sample solution must be pumped through the extraction capillary in the extraction process, various types of fine polymeric filaments can be introduced as novel extraction media [10,12,13]. In this work, the possibility of the braided fiber has been studied as a novel extraction medium in microscale sample preparation. As the material for the braid, a bundle
of
Zylon,
poly(p-phenylene-2,6-benzobisoxazole),
filaments
[7,9]
was
introduced. Phenanthrene, which is a kind of polycyclic aromatic hydrocarbons (PAHs), was employed as the sample probe for evaluating the fundamental extraction performance. The extraction and desorption conditions of Zylon-based braid were optimized for phenanthrene. Finally, thermal desorption was also studied by applying voltage to the metal wire introduced to the center opening of the braid, and the possibility as a sample preparation device with thermally-assisted desorption was also investigated. 2. Experimental 2.1. Reagents and solvents
5
All conventional reagents and solvents were obtained from Tokyo Kasei Industries (Tokyo, Japan), Kishida Chemical (Osaka, Japan) or Nacalai Tesque (Kyoto, Japan). These reagents and solvents were of analytical reagent grade and used without any further purification. Methanol, dichloromethane, toluene and hexane were used as desorption solvent, and methanol was also employed as the mobile phase in LC. For the preparation of standard samples and mobile phases, water was prepared using by a Milli-Q
water
purification
system
(Merck
Millipore,
Darmstadt,
Germany).
Poly(etheretherketone) (PEEK) and poly(tetrafluoroethylene) (PTFE) tube were obtained
from
GL
Sciences
(Tokyo,
Japan).
Zylon,
poly(p-phenylene-2,6-
benzobisoxazole), fiber of 166 filaments, ca. 11.5 μm o.d. was obtained from Toyobo (Otsu, Japan). A 304-type stainless-steel wire of 0.2 mm o.d., used as the inner core of the braid, was purchased from Nilaco (Tokyo, Japan). 2.2. Preparation of braid The braid was made of four bundles of Zylon fiber and a stainless-steel wire. First, four Zylon bundles were tied to form a knot at one end, and then, the knotted end was dropped into the center hole of a laboratory-made specially-designed device for the braiding as illustrated in Fig. 1. Four bundles were separated and placed on the top of the braiding device, where set a bobbin for each bundle and a center weight to the knotted end.
The dish-shape support at the top of the device was made of soft
polyurethane and has four notches (placed at the position of 0°, 90°, 180° and 270°) to fix the each bundle of fiber. On the basis of the results in the preliminary experiments, the weight of these bobbins was determined as 60 g, while the weight of the center weight was changed from 100 to 300 g, as summarized in Table 1. As illustrated in Fig. 2, after inserting a stainless-steel wire into the center hole vertically, fiber bundles were braided up on the basis of the following procedures; i) a pair of bundles placed at the opposite of the circular plate (a and c) were simultaneously moved clockwise 180°, and then, ii) another pair of bundles (b and d)
6
were also simultaneously moved counterclockwise 180°. This two-step process was repeated twice, as explained in Fig. 2, to return to the original configuration. About 150 cycles of these manual operations, from i) to iv) in Fig. 2, were necessary for the preparation of a braid having about 10 cm length. Typical braid prepared in a similar manner is shown in Fig. 3. The resulting braid has non-braided sections at both ends, which enable an easy electronic wire connection for resistive heating. Several braidtype extraction media were prepared as summarized in Table 1. Increasing the center weight, the outer diameter of the resulting braids was decreased on the basis of a general rule of the braid preparation [1]. As can be expected, the outer diameter of the braid could also be changed by the diameter of the stainless steel wire. 2.3. Preparation of fiber-packed extraction device Before the packing to the capillary tube, all the braids were carefully rinsed with methanol. For the preparation of the fiber-packed extraction tube, a Zylon braid was packed into a PEEK tube of 0.50 mm i.d., 1.58 mm o.d., 60 mm length. The fiber packing was carried out as a similar manner as described previously [34]. In order to pack the braid, poly(vinylidene fluoride) (PVF) fishing line of 0.64 mm o.d. was inserted into the PEEK tube as a guide fiber. The end of guide fiber was inserted into the tube again to form a loop outside the PEEK tube. As described above, the braid fiber has a section of non-braided fiber at the both ends. One of the non-braided sections was inserted to the loop of the PVF guide fiber, and pulled the PVF guide from the other side of the PEEK tube, where a braid having a slightly large outer diameter could be inserted to the PEEK tube as confirmed in the preliminary experiments. Since the availability of the inner diameter of the PEEK tube that was used as the housing of the extraction capillary was somewhat limited, a combination of the braid of 0.51 mm o.d. and a PEEK tube of 0.50 mm i.d. (Entry 1 in Table 1) was chosen for the preparation of the extraction capillary in the following experiments. Fiber-packed extraction capillary was prepared by cut the stainless-steel wire
7
leaving 50 mm from both ends of the tubing, and also cut the braid at the both ends of the PEEK tube. The length of the resulting packed section was 60 mm, while the total length of the stainless-steel wire was 160 mm. Fig. 4 shows an illustration of the extraction capillary. The total amount of Zylon filaments packed in the extraction tube was about 10.2 mg, and the packing density include the stainless-steel wire was calculated to be about 71.3%, where the packing density was calculated on the basis of total cross section of the filaments and the stainless-steel wire to the cross section of PEEK tube opening The void volume of the extraction capillary was about 3.4 μL. The sections of the extra 50 mm length each of the metal wire, at the both ends of the PEEK tube, were specially-designed for the electric connection to the power supply as illustrated in Fig. 5. All the tubing, the extraction capillary and the electric wiring were installed into a set of PTFE tee connectors (GL Sciences) with modifications to ensure to avoid any undesirable dead volume in the device. 2.4. LC System LC system was consisted of an 880-PU pump (Jasco, Tokyo, Japan), a model UV875 UV-Vis absorption detector (Jasco) and a Model 7125 injector (Rheodyne, Cotati, CA, USA) with a 40-μL loop. As a conventional octadecylsilica (ODS) analytical column, Wakopak Eco-ODS (4.6 mm i.d., 150 mm length, 5 μm particle size; Wako Pure Chemical Industries, Osaka, Japan) was used. The mobile phase was prepared with a mixture of methanol and water (85:15) and the typical flowrate was set at 1.0 mL/min. The detection was carried out using the above mentioned UV detector with the detection wavelength at 254 nm. All the LC runs were conducted at the room temperature controlled by an air conditioner at 23.5-24.5°C. For data acquisition and processing, Borwin Chromatography Software (Jasco) running on a personal computer was employed. All the measurements were carried out at least five times, and the relative standard deviations (RSDs) were less than 4.0% for all the chromatographic analyses. 2.5. Extraction and desorption procedure
8
Two syringe pumps (Microfeeder MF-2, Azuma Denki Kogyo, Tokyo, Japan) with a gas tight syringe (MS-GAN 100, Ito Corporation, Shizuoka, Japan) were employed for pumping the sample solution and desorption solvent to the extraction capillary. The extraction process was carried out by pumping 1.0 mL of an aqueous sample solution into the extraction device, and then the remaining solution inside the tubing was removed by passing 5.0 mL of air with a micro-syringe operated manually for about 30 sec. Next, desorption solvent was pumped at the flowrate of 20 μL/min. A model 7125 injector with a 40-μL loop was placed between the syringe pump and the extraction device for pumping of two organic solvents sequentially as described below. The eluate from the extraction capillary was collected by a conventional micro-syringe (100 μL volume; MS-R 100, Ito Corporation) for subsequent analysis in LC, where the needle of the micro-syringe was directly inserted into the outlet capillary of the extraction device. A conditioning procedure was carried out by passing 5.0 mL of methanol, 1.0 mL of water and 5.0 mL of air between runs. 3. Results and Discussion 3.1. Optimization of extraction flowrates For an effective extraction of the analyte, extraction flowrates of 40, 60, 80 and 120 μL/min were initially studied, where the sample volume of 1.0 mL was maintained. The results are summarized in Table 2. More than 90% of phenanthrene could be extracted in all the flowrate studied, where it was confirmed that the extraction efficiency was slightly increased at a slower flowrate. On the basis of the above results, additional intensive experiments was carried out, where the extraction flowrate of 20 μL/min was also considered. The results are the statistically the same as that obtained at 40 μL/min. In addition, it was also confirmed in this intensive experiments for the comparison of extraction flowrate of 40 and 60 μL/min. that the extraction efficiency at 40 μL/min is slightly better than that at 60 μL/min. Therefore, 40 μL/min was chosen as the optimum extraction flowrate
9
under the consideration of the total analysis time. 3.2. Optimization of desorption solvent Prior to the optimization of the desorption conditions, several typical organic solvents such as n-hexane, toluene, dichloromethane, acetone and methanol were investigated in the preliminary experiment, and a better desorption efficiency was observed with acetone as the desorption solvent. However, as can be expected from the results in our previous publications [28], a non-polar organic solvent has a better desorption capability than a polar organic solvent, for desorbing phenanthrene from Zylon, due to the surface characteristics. For the desorption of phenanthrene from the braid-type extraction medium, one can assume that a certain amount of water was still remain trapped in between the fine filaments when pumping a non-polar desorption solvent only.
Since the braid was consisted of bundles of fine filaments, the
configuration of these bundles could be regarded as quite complex compared with conventional fiber-packed extraction capillaries [12,13]. In contrast to the conventional fiber-packed capillary, where a bundles of filaments was packed longitudinally into the housing capillary, a different desorption process should be considered for an effective desorption from braid-type extraction medium. In this work, a sequential pumping process was introduced for the desorption step, where acetone was delivered first followed by n-hexane, allowing both an effective removal of water from the extraction tube by acetone and also an effective desorption of the extracted non-polar analyte by n-hexane. The sequential pumping procedure in the desorption process is shown in Fig. 6, where the loop in a six-port valve was filled with non-polar solvent (2nd desorption solvent) followed by a partial replacement with polar solvent (1st desorption solvent). The resulting set of desorption solvents, such as acetone and n-hexane in this order, was delivered to the extraction capillary. Table 3 summarizes the desorption efficiencies obtained with this sequential pumping procedure of two solvents, where the ratio between non-polar and polar solvents was
10
changed. The RSDs for five repeated runs are also in the table. Introducing the sequential pumping of two organic solvents, acetone and n-hexane, the desorption efficiency was significantly improved. The results suggest that the trace amount of water in the extraction capillary was effectively washed out with a plug of acetone in advance of the desorption of phenanthrene by n-hexane. On the basis of these results, the sequential pumping of acetone and n-hexane, 5 μL and 35 μL, respectively, was employed in the following experiments. 3.3. Thermal desorption For further improving the desorption efficiency, thermal desorption was studied. As described in the previous section, the extraction tube has a specially-designed configuration that is well-compatible to resistive heating during the desorption process. Surface temperature of the extraction device during the thermal desorption process was observed by employing thermographic camera (FLIR i7, FLIR Systems, Wilsonville, OR, USA). With a laboratory-made power supply, a programmable application of an AC voltage was carried out. Based on the systematic consideration in the preliminary experiments, the voltage application program was set as: the application of the voltage for 3 s followed by no application time for 27 s. The application voltage and the application program were adjusted in the range not to evaporate the desorption solvents in the tubing. For the desorption of the extracted analyte from the extraction capillary, the above voltage application program was repeated four times with a flow of desorption solvent at 20 μL/min for two min, allowing the delivery of 40-μL desorption solvent through the extraction capillary under an elevated temperature by resistive heating. Fig. 7 shows typical thermographic picture during the resistive heating and the corresponding desorption efficiencies with changing the applied voltage were summarized in Table 4. Compared with the desorption without voltage application, the desorption was significantly effective when a few volts were applied to the stainless-
11
steel wire in the extraction capillary, and the analyte were completely desorbed only with a low applied voltage at 2V or 3V. In Fig. 8, a comparison of the chromatograms of phenanthrene obtained with and without sample preparation process developed in this work. In the optimized conditions, the LOQ and the LOD for phenanthrene were 0.048 and 0.014 μg/mL, respectively, where the entire recovery was 96.6% with the RSD of less than 3.0% (n=5). More than 100 runs could be performed without any significant problems such as a decrease in the extraction power, suggesting a good stability for repeatable use of the miniaturized sample preparation device developed in this work. 4. Conclusions Introducing a braid-type fiber-packed capillary, a new miniaturized sample preparation device was developed. The extraction conditions were systematically optimized, and the efficient extraction was confirmed under the optimized conditions with a sequential delivery of two organic solvents. With the application of a low voltage to the metal wire included in the extraction device, an experimentally complete desorption was achieved for phenanthrene in water samples. Although a more systematic investigation must be made, the unique configuration of the extraction cartridge could be regarded as one of the most promising technique in the miniaturized sample preparation, and a wide range of applications could be expected in the near future. A promising possibility of this wire-in-braid configuration is expected especially for the use as a novel interface or modulator of two-dimensional chromatographic separations [35-41]. Surface-polymercoated [13,24] or surface-modified fibrous materials [26,42] could also be employed to enhance the particular selectivity to a certain class of compounds.
12
Acknowledgements A part of this study was financially supported by JSPS KAKENHI (Grant Number 18K05169).
KN and OS acknowledge the support from Toyohashi University of
Technology. The authors would like to thank Mr. Y. Nomura of Toyobo for his valuable technical advice.
13
References [1]
M. Tada, Comprehensive Treatise of Braids I: Maru-dai braids, first ed., Texte, Inc., Tokyo, 1996.
[2]
E. Tanaka, M. Terada, T. Nakamura, S. Misawa, C. Wakasugi, Forensic analysis of eleven cyclic antidepressants in human biological samples using a new reversed-phase chromatographic column of 2 μm porous microspherical silica gel, J. Chromatogr. B, 692 (1997) 405-412. https://doi.org/10.1016/S03784347(96)00510-5.
[3]
P. Ghahramani, M.S. Lennard, Quantitative analysis of amitriptyline and nortriptyline in human plasma and liver microsomal preparations by highperformance liquid chromatography, J. Chromatogr. B, 685 (1996) 307-313. https://doi.org/10.1016/S0378-4347(96)00193-4.
[4]
G. Aymard, P. Livi, Y.T. Pham, B. Diquet, Sensitive and rapid method for the simultaneous quantification of five antidepressants with their respective metabolites in plasma using high-performance liquid chromatography with diode-array
detection,
J.
Chromatogr.
B,
700
(1997)
183-189.
https://doi.org/10.1016/S0378-4347(97)00327-7. [5]
E. Baltussen, C.A. Cramers, P.J.F. Sandra, Sorptive sample preparation - a review, Anal. Bioanal. Chem., 373 (2002) 3-22. https://doi.org/10.1007/s00216-0021266-2.
[6]
S.H. Salleh, Y. Saito, K. Jinno, An approach to solventless sample preparation procedure
for
pesticides
analysis
using
solid
phase
microextraction/supercritical fluid extraction technique, Anal. Chim. Acta, 418 (2000) 69-77. https://doi.org/10.1016/S0003-2670(00)00944-2. [7]
Y. Saito, A. Tahara, M. Imaizumi, T. Takeichi, H. Wada, K. Jinno, Polymer-coated fibrous materials as the stationary phase in packed capillary gas chromatography,
Anal.
Chem.,
14
75
(2003)
5525-5531.
https://doi.org/10.1021/ac030052h. [8]
Y. Saito, M. Ogawa, M. Imaizumi, K. Ban, A. Abe, T. Takeichi, H. Wada, K. Jinno, High-temperature separation with polymer-coated fiber in packed capillary gas chromatography,
Anal.
Bioanal.
Chem.,
382
(2005)
825-829.
https://doi.org/10.1007/s00216-004-2967-5. [9]
Y. Saito, M. Imaizumi, K. Nakata, T. Takeichi, K. Kotera, H. Wada, K. Jinno, Fibrous rigid-rod heterocyclic polymer as the stationary phase in packed capillary gas chromatography,
J.
Microcol.
Sep.,
13
(2001)
259-264.
https://doi.org/10.1002/mcs.10005. [10]
Y. Saito, K. Jinno, Miniaturized sample preparation combined with liquid phase separations,
J.
Chromatogr.
A,
1000
(2003)
53-67.
https://doi.org/10.1016/S0021-9673(03)00307-8. [11]
Y. Bu, J. Feng, M. Sun, C. Zhou, C. Luo, Facile and efficient poly(ethylene terephthalate) fibers-in-tube for online solid-phase microextraction towards polycyclic aromatic hydrocarbons, Anal. Bioanal. Chem., 408 (2016) 48714882. https://doi.org/10.1007/s00216-016-9567-z.
[12]
K. Jinno, M. Ogawa, I. Ueta, Y. Saito, Miniaturized sample preparation using a fiber-packed capillary as the medium, Trends Anal. Chem., 26 (2007) 27-35. https://doi.org/10.1016/j.trac.2006.11.008.
[13]
Y. Saito, M. Nojiri, M. Imaizumi, Y. Nakao, Y. Morishima, H. Kanehara, H. Matsuura, K. Kotera, H. Wada, K. Jinno, Polymer-coated synthetic fibers designed for miniaturized sample preparation process, J. Chromatogr. A, 975 (2002) 105-112. https://doi.org/10.1016/S0021-9673(02)01333-X.
[14]
M. Imaizumi, Y. Saito, K. Ban, H. Wada, M. Hayashida, K. Jinno, In-valve sample preparation cartridge designed for microcolumn liquid chromatography, Chromatographia, 60 (2004) 619-623. https://doi.org/10.1365/s10337-0040428-0.
15
[15]
M. Ogawa, Y. Saito, I. Ueta, K. Jinno, Fiber-packed needle for dynamic extraction of aromatic compounds, Anal. Bioanal. Chem., 388 (2007) 619-625. https://doi.org/10.1007/s00216-007-1255-6.
[16]
M. Ogawa, Y. Saito, S. Shirai, Y. Kiso, K. Jinno, Determination of Bisphenol A in water using a packed needle extraction device, Chromatographia, 69 (2009) 685-690. https://doi.org/10.1365/s10337-008-0928-4.
[17]
I. Ueta, Y. Saito, N.B.A. Ghani, M. Ogawa, K. Yogo, A. Abe, S. Shirai, K. Jinno, Rapid determination of ethylene oxide with fiber-packed sample preparation needle, J.
Chromatogr.
A,
1216
(2009)
2848-2853.
https://doi.org/10.1016/j.chroma.2008.10.107. [18]
I. Ueta, Y. Saito, Needle-type extraction device designed for rapid and sensitive analysis
in
gas
chromatography,
Anal.
Sci.,
30
(2014)
105-110.
https://doi.org/10.2116/analsci.30.105. [19]
A. Gutiérrez-Serpa, D. Schorn-García, F. Jiménez-Moreno, A.I. JiménezAbizanda, V. Pino, Braid solid-phase microextraction of polycyclic aromatic hydrocarbons by using fibers coated with silver-based nanomaterials in combination with HPLC with fluorometric detection, Microchim. Acta, 186 (2019) 311. https://doi.org/10.1007/s00604-019-3452-3.
[20]
R.D. Stanelle, M. Mignanelli, P. Brown, R.K. Marcus, Capillary-channeled polymer (C-CP) fibers as a stationary phase in microbore high-performance liquid chromatography columns, Anal. Bioanal. Chem., 384 (2006) 250-258. https://doi.org/10.1007/s00216-005-0117-3.
[21]
D.K. Nelson, R.K. Marcus, A novel stationary phase: Capillary-channeled polymer (C-CP) fibers for HPLC separations of proteins, J. Chromatogr. Sci., 41 (2003) 475-479. https://doi.org/10.1093/chromsci/41.9.475.
[22]
R.K. Marcus, W.C. Davis, B.C. Knippel, L. LaMotte, T.A. Hill, D. Perahia, J.D. Jenkins, Capillary-channeled polymer fibers as stationary phases in liquid
16
chromatography
separations,
J.
Chromatogr.
A,
986
(2003)
17-31.
https://doi.org/10.1016/S0021-9673(02)01835-6. [23]
M. Ogawa, Y. Saito, M. Imaizumi, H. Wada, K. Jinno, Longitudinal miniaturization of fiber-packed capillary column in high temperature gas chromatography, Chromatographia, 63 (2006) 459-463. https://doi.org/10.1365/s10337-0060771-4.
[24]
Y. Saito, A. Tahara, M. Ogawa, M. Imaizumi, K. Ban, H. Wada, K. Jinno, Polymer-coated
fibrous
chromatography,
stationary
Anal.
phase
Sci.,
in
20
packed-capillary (2004)
gas
335-339.
https://doi.org/10.2116/analsci.20.335. [25]
Y. Saito, M. Ogawa, M. Imaizumi, K. Ban, A. Abe, T. Takeichi, H. Wada, K. Jinno, Short metal capillary columns packed with polymer-coated fibrous materials in high-temperature gas chromatography, J. Chromatogr. Sci., 43 (2005) 536-541. https://doi.org/10.1093/chromsci/43.10.536.
[26]
A. Abe, Y. Saito, M. Imaizumi, M. Ogawa, T. Takeichi, K. Jinno, Surface derivatization of poly(p-phenylene terephthalamide) fiber designed for novel separation and extraction media, J. Sep. Sci., 28 (2005) 2413-2418. https://doi.org/10.1002/jssc.200401938.
[27]
S.H. Salleh, Y. Saito, K. Jinno, Solventless sample preparation procedure for organophosphorus pesticides analysis using solid phase microextraction and on-line supercritical fluid extraction/high performance liquid chromatography technique,
Anal.
Chim.
Acta,
433
(2001)
207-215.
https://doi.org/10.1016/S0003-2670(01)00790-5. [28]
Y. Saito, M. Imaizumi, T. Takeichi, K. Jinno, Miniaturized fiber-in-tube solidphase extraction as the sample preconcentration method for microcolumn liquid-phase separations, Anal. Bioanal. Chem., 372 (2002) 164-168. https://doi.org/10.1007/s00216-001-1126-5.
17
[29]
Y. Saito, Y. Nakao, M. Imaizumi, Y. Morishima, Y. Kiso, K. Jinno, Miniaturized solid-phase extraction as a sample preparation technique for the determination of
phthalates
in
water,
Anal.
Bioanal.
Chem.,
373
(2002)
81-86.
https://doi.org/10.1007/s00216-002-1270-6. [30]
B. Riahi-Zanjani, M. Balali-Mood, A. Asoodeh, Z. Es’haghi, A. GhoraniAzam, Developing a new sensitive solid-phase microextraction fiber based on carbon nanotubes for preconcentration of morphine, Appl. Nanosci., 8 (2018) 2047-2056. https://doi.org/10.1007/s13204-018-0882-x.
[31]
S.X.L. Goha, H.K. Lee, An alternative perspective of hollow fiber-mediated extraction: Bundled hollow fiber array-liquid-phase microextraction with sonication-assisted desorption and liquid chromatography-tandem mass spectrometry for determination of estrogens in aqueous matrices, J. Chromatogr.
A,
1488
(2017)
26-36.
http://dx.doi.org/10.1016/j.chroma.2017.01.081. [32]
J. Pawliszyn (Ed.), Applications of Solid Phase Microextraction, Royal Society of Chemistry, Letchworth, 1999.
[33]
J. Pawliszyn, H.L. Lord (Eds.), Handbook of Sample Preparation, John Wiley & Sons, Hoboken, 2010.
[34]
Y. Saito, M. Imaizumi, K. Ban, A. Tahara, H. Wada, K. Jinno, Development of miniaturized sample preparation with fibrous extraction media, J. Chromatogr. A, 1025 (2004) 27-32. https://doi.org/10.1016/j.chroma.2003.08.098.
[35]
D. Ryan, P. Marriott, Comprehensive two-dimensional gas chromatography, Anal. Bioanal. Chem., 376 (2003) 295–297. https://doi.org/10.1007/s00216003-1934-x.
[36]
J. Harynuk, T. Gorecki, New liquid nitrogen cryogenic modulator for comprehensive two-dimensional gas chromatography, J. Chromatogr. A, 1019 (2003) 53–63. https://doi.org/10.1016/j.chroma.2003.08.097.
18
[37]
F. Begnaud, C. Debonneville, J.-P. Probst, A. Chaintreau, P.D. Morrison, J.L. Adcock, P.J. Marriott, Effects of variation in modulator temperature during cryogenic modulation in comprehensive two-dimensional gas chromatography, J. Sep. Sci. 32 (2009) 3144–3151. https://doi.org/10.1002/jssc.200900290.
[38]
P.Q. Tranchida, M. Zoccali, F.A. Franchina, A. Cotroneo, P. Dugo, L. Mondello, Gas velocity at the point of re-injection: An additional parameter in comprehensive two-dimensional gas chromatography optimization, J. Chromatogr. A, 1314 (2013) 216–223. http://dx.doi.org/10.1016/j.chroma.2013.09.025.
[39]
P.Q. Tranchida, F.A. Franchina, M. Zoccali, I. Bonaccorsi, F. Cacciola, L. Mondello, A direct sensitivity comparison between flow-modulated comprehensive 2D and 1D GC in untargeted and targeted MS-based experiments, J. Sep. Sci. 36 (2013) 2746–2752. https://doi.org/10.1002/jssc.201300423.
[40]
H.D. Bahaghighat, C.E. Freye, D.V. Gough, P.E. Sudol, R.E. Synovec, Ultrafast separations via pulse flow valve modulation to enable high peak capacity multidimensional gas chromatography, J. Chromatogr. A, 1573 (2018) 115–124. https://doi.org/10.1016/j.chroma.2018.08.001.
[41]
H.D. Bahaghighat, C.E. Freye, D.V. Gough, R.E. Synovec, Comprehensive twodimensional gas chromatography and time-of-flight mass spectrometry detection with a 50 ms modulation period, J. Chromatogr. A, 1583 (2019) 117– 123. https://doi.org/10.1016/j.chroma.2018.11.027.
[42]
S. Shirai, Y. Saito, Y. Sakurai, I. Ueta, K. Jinno, Retention behavior on aminoethyl-modified poly(p-phenylene terephthalamide) fiber stationary phases in gas chromatography, Anal. Sci. 26 (2010) 1011-1014. https://doi.org/10.2116/analsci.26.1011.
19
Figure Captions
20
Figure 1. A laboratory-made set-up for the preparation of braided fiber. (A) Center weight; (B) bobbins; (C) stainless-steel wire.
21
Figure 2. Preparation of braid-type extraction medium. Bobbin positions (a)-(d) correspond that in Fig. 1. First, i) a pair of bundles placed at the opposite of the circular plate (a and c) were simultaneously moved clockwise 180°, and then, ii) another pair of bundles (b and d) were also simultaneously moved counterclockwise 180°. This twostep process was repeated once more as shown in iii) and iv), to return to the original configuration i).
22
Figure 3. Typical photograph of a braided fiber prepared in this work.
23
Figure 4. Schematic of the braid-packed extraction capillary with a stainless-steel wire therein.
Figure 5. Illustration of the miniaturized SPE device connected with an electric power supply developed in this work. .
24
Figure 6. Scheme of the sequential pumping procedure with two types of organic solvents. (A) Fill the sample loop of the injection valve with the 2nd desorption solvent, (B) switch the injection valve, and inject certain volume of 1st desorption solvent, where a small volume of air was inserted between section of the 2nd and 1st desorption solvents, (C) switch the valve again, and start the sequential pumping of two desorption solvents.
25
Figure 7. Thermographic observation of the surface temperature of the extraction capillary during a resistive heating process. Applied voltage: (A) 0V, (B) 1V, (C), 2V and (D) 3V. Other conditions are in the text.
26
Figure 8.
Comparison of chromatograms observed for (a) the sample solution
preconcentrated
by
the
miniaturized
SPE
device,
and
(b)
that
without
preconcentration. Extraction conditions: extraction flowrate, 40 μL/min; extraction volume, 1.0 mL; concentration of phenanthrene standard, 1.0 μg/mL. Desorption conditions: desorption flowrate, 20 μL/min; desorption solvent volume, 40 μL; desorption solvent and volume, acetone 5 μL + n-hexane 35 μL. Thermal desorption condition: applied voltage, 2V; voltage was applied continuously while desorption process. LC conditions: mobile phase, methanol/water = (85/15); flowrate, 1.0 mL/min; detection, UV at 254 nm.
27
Table 1. Various types of braids and the corresponding extraction capillaries prepared in this work. braid entr y 1 2 3 4 5
o.d. of stainlesssteel wire (mm) 0.2 0.2 0.1 0.1 0.1
extraction capillary
center weight (g)
o.d. of braid (mm)
void volume (µL)
packing density (%)
100 200 100 200 300
0.51 0.48 0.47 0.43 0.39
3.38 4.85 5.64 6.32 6.78
71.3 58.9 52.1 46.3 42.5
28
40 60 80 120
Table 2. Comparison of extraction flowrates. extraction flowrate extraction efficiency (%) (µL/min) 96.0 94.2 90.8 90.1
29
Table 3. Comparison of desorption solvent. desorption solvent volume desorption efficiency (%) (acetone + n-hexane) 40 μL + 0 μL 68.4 20 μL + 20 μL 78.0 10 μL + 30 μL 83.7 5 μL + 35 μL 87.5 0 μL + 40 μL 22.7
30
RSD (%) 2.5 3.7 2.7 0.6 3.5
Table 4. Surface temperature of the extraction capillary and the desorption efficiency with thermal desorption at different applied voltages. surface temperature applied voltage (V) desorption efficiency (%) RSD (%) of capillary tube (ºC) 0 22 87.5 0.6 1 26 95.0 1.2 2 35 100.6 1.3 3 44 99.4 2.1
31
Braid Configuration Designed for Fiber-Packed Capillary in Microscale Sample Preparation Koki Nakagami , Tomoya Monobe , Ohjiro Sumiya , Kazunori Takashima , Ikuo Ueta , Yoshihiro Saito PII: DOI: Reference:
S0021-9673(19)31123-9 https://doi.org/10.1016/j.chroma.2019.460694 CHROMA 460694
To appear in:
Journal of Chromatography A
Received date: Revised date: Accepted date:
2 August 2019 7 November 2019 7 November 2019
Please cite this article as: Koki Nakagami , Tomoya Monobe , Ohjiro Sumiya , Kazunori Takashima , Ikuo Ueta , Yoshihiro Saito , Braid Configuration Designed for Fiber-Packed Capillary in Microscale Sample Preparation, Journal of Chromatography A (2019), doi: https://doi.org/10.1016/j.chroma.2019.460694
This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2019 Published by Elsevier B.V.
Highlights
Miniaturized sample preparation with braid-type extraction medium was developed.
The extraction capillary was prepared using the braid with a metal wire inside.
Applying low voltages to the metal wire, a heat-assisted desorption was made.
1
Braid Configuration Designed for Fiber-Packed Capillary in Microscale Sample Preparation Koki Nakagami1, Tomoya Monobe1, Ohjiro Sumiya1, Kazunori Takashima1, Ikuo Ueta2 and Yoshihiro Saito1,* 1Department
of Applied Chemistry and Life Science, Toyohashi University of Technology,
Toyohashi 441-8580, Japan 2Department
of Applied Chemistry, University of Yamanashi, Kofu 400-8511, Japan
*Corresponding Author at: Department of Applied Chemistry and Life Science, Toyohashi University of Technology, Toyohashi 441-8580, Japan. E-mail address: [email protected] (Y. Saito)
2
Abstract A novel miniaturized sample preparation device with braid-type extraction medium was successfully developed. Introducing a set of bundles of fine synthetic filaments as the materials of the braid-type extraction medium and also the application of an appropriate tension during the braiding process, the outer diameter of the resulting braid has been controlled. Optimization of the tension enables an easy preparation of a group of braids that can be well-compatible to various internal diameters of capillaries to be packed.
The extraction conditions were systematically optimized, and the
efficient extraction was confirmed under the optimized conditions. All the parameters affects the desorption efficiency were also optimized, where typical extraction efficiency was more than 90% for the extraction of phenanthrene (1.0 μg/mL) in water. The extracted analyte was desorbed sufficiently by employing a sequential pumping process of two organic solvents. During the preparation of the braid, a different type of fibrous materials could be inserted to the opening at the center of the braid. Taking advantage of this feature of the braid, a stainless steel wire was inserted into the center of the braid. By applying low voltages to the stainless steel wire, a heat-assisted desorption of the extracted analyte was also studied.
Experimentally complete
desorption (higher than 99.0%) was obtained with the voltage application of 2V. The lowest limit of quantification (LOQ) and the lowest limit of detection (LOD) for phenanthrene were 0.048 and 0.014 μg/mL, respectively. Keywords: Braid; Synthetic fiber; Sample preparation; Solid phase extraction; Thermal desorption
3
1. Introduction Braid is one of the most popular Japanese traditional craft, and it has been employed as a part of accessories since ancient times [1]. Typical braid is consisted of a set of fiber bundles. Because of the excellent mechanical strength and flexibility, there are many types of the industrial applications such as, rope and flexible high pressure tubing. Changing the tension during the braiding preparation, the outer diameter could be reproducibly controlled, which enables an easy preparation of a group of braids compatible to be inserted into various sizes of capillaries. In addition, typical braid has an open channel in the center. This is another advantageous feature of the braid, and therefore, a different type of fibrous materials can be successfully inserted into the center opening, suggesting a possibility to the development of novel hybrid materials for a sample preparation device in separation science. Liquid chromatography (LC) and gas chromatography (GC) have been regarded as strong tools for the analysis of various complex sample matrices. However, the analyst still needs an appropriate sample preparation in most cases, due to a low concentration of the target compounds and the complexity of the sample matrices. Extraction is one of the most fundamental sample preparation techniques to concentrate the target compounds in a typical complex sample matrix. In the extraction methods conventionally employed, liquid-liquid extraction, has been widely used [2-4], however, the method has several disadvantages such as sample loss during manual handling and a large volume consumption of organic solvents. Solid phase extraction (SPE) has been recognized as an alternative method because of its small organic solvent consumption and an easy operation [5,6]. As one of the approach to the down-sizing of the sample preparation and the subsequent chromatographic separations in the past decades, various types of synthetic fibrous materials have been introduced in separation science due to the excellent resistance to high temperature and organic solvents [7-9], where these fibrous materials are employed as the extraction medium in
4
sample preparation device [10-19] and the stationary phase in chromatographic separations [20-26]. Various synthetic fibers, as typically mentioned above, were successfully introduced as a SPE medium for the preconcentration and derivatization of target analytes in aqueous and air matrices [27-31]. In these applications, a bundle of fine filaments was packed longitudinally into a capillary to prepare the miniaturized extraction cartridges for the sample preparation and the columns for chromatographic separations. Compared with conventional solid-phase microextraction (SPME) and SPE using particle-packed cartridges [32,33], these fine-filaments-packed capillaries could have additional advantages such as easy on-line coupling to various chromatographic techniques.
Taking advantage of the feature of the easy on-line coupling of the
extraction method to the separation system, the extraction capillary could be further applied to a modulator in multi-dimensional separations.
Although typical liquid
sample solution must be pumped through the extraction capillary in the extraction process, various types of fine polymeric filaments can be introduced as novel extraction media [10,12,13]. In this work, the possibility of the braided fiber has been studied as a novel extraction medium in microscale sample preparation. As the material for the braid, a bundle
of
Zylon,
poly(p-phenylene-2,6-benzobisoxazole),
filaments
[7,9]
was
introduced. Phenanthrene, which is a kind of polycyclic aromatic hydrocarbons (PAHs), was employed as the sample probe for evaluating the fundamental extraction performance. The extraction and desorption conditions of Zylon-based braid were optimized for phenanthrene. Finally, thermal desorption was also studied by applying voltage to the metal wire introduced to the center opening of the braid, and the possibility as a sample preparation device with thermally-assisted desorption was also investigated. 2. Experimental 2.1. Reagents and solvents
5
All conventional reagents and solvents were obtained from Tokyo Kasei Industries (Tokyo, Japan), Kishida Chemical (Osaka, Japan) or Nacalai Tesque (Kyoto, Japan). These reagents and solvents were of analytical reagent grade and used without any further purification. Methanol, dichloromethane, toluene and hexane were used as desorption solvent, and methanol was also employed as the mobile phase in LC. For the preparation of standard samples and mobile phases, water was prepared using by a Milli-Q
water
purification
system
(Merck
Millipore,
Darmstadt,
Germany).
Poly(etheretherketone) (PEEK) and poly(tetrafluoroethylene) (PTFE) tube were obtained
from
GL
Sciences
(Tokyo,
Japan).
Zylon,
poly(p-phenylene-2,6-
benzobisoxazole), fiber of 166 filaments, ca. 11.5 μm o.d. was obtained from Toyobo (Otsu, Japan). A 304-type stainless-steel wire of 0.2 mm o.d., used as the inner core of the braid, was purchased from Nilaco (Tokyo, Japan). 2.2. Preparation of braid The braid was made of four bundles of Zylon fiber and a stainless-steel wire. First, four Zylon bundles were tied to form a knot at one end, and then, the knotted end was dropped into the center hole of a laboratory-made specially-designed device for the braiding as illustrated in Fig. 1. Four bundles were separated and placed on the top of the braiding device, where set a bobbin for each bundle and a center weight to the knotted end.
The dish-shape support at the top of the device was made of soft
polyurethane and has four notches (placed at the position of 0°, 90°, 180° and 270°) to fix the each bundle of fiber. On the basis of the results in the preliminary experiments, the weight of these bobbins was determined as 60 g, while the weight of the center weight was changed from 100 to 300 g, as summarized in Table 1. As illustrated in Fig. 2, after inserting a stainless-steel wire into the center hole vertically, fiber bundles were braided up on the basis of the following procedures; i) a pair of bundles placed at the opposite of the circular plate (a and c) were simultaneously moved clockwise 180°, and then, ii) another pair of bundles (b and d)
6
were also simultaneously moved counterclockwise 180°. This two-step process was repeated twice, as explained in Fig. 2, to return to the original configuration. About 150 cycles of these manual operations, from i) to iv) in Fig. 2, were necessary for the preparation of a braid having about 10 cm length. Typical braid prepared in a similar manner is shown in Fig. 3. The resulting braid has non-braided sections at both ends, which enable an easy electronic wire connection for resistive heating. Several braidtype extraction media were prepared as summarized in Table 1. Increasing the center weight, the outer diameter of the resulting braids was decreased on the basis of a general rule of the braid preparation [1]. As can be expected, the outer diameter of the braid could also be changed by the diameter of the stainless steel wire. 2.3. Preparation of fiber-packed extraction device Before the packing to the capillary tube, all the braids were carefully rinsed with methanol. For the preparation of the fiber-packed extraction tube, a Zylon braid was packed into a PEEK tube of 0.50 mm i.d., 1.58 mm o.d., 60 mm length. The fiber packing was carried out as a similar manner as described previously [34]. In order to pack the braid, poly(vinylidene fluoride) (PVF) fishing line of 0.64 mm o.d. was inserted into the PEEK tube as a guide fiber. The end of guide fiber was inserted into the tube again to form a loop outside the PEEK tube. As described above, the braid fiber has a section of non-braided fiber at the both ends. One of the non-braided sections was inserted to the loop of the PVF guide fiber, and pulled the PVF guide from the other side of the PEEK tube, where a braid having a slightly large outer diameter could be inserted to the PEEK tube as confirmed in the preliminary experiments. Since the availability of the inner diameter of the PEEK tube that was used as the housing of the extraction capillary was somewhat limited, a combination of the braid of 0.51 mm o.d. and a PEEK tube of 0.50 mm i.d. (Entry 1 in Table 1) was chosen for the preparation of the extraction capillary in the following experiments. Fiber-packed extraction capillary was prepared by cut the stainless-steel wire
7
leaving 50 mm from both ends of the tubing, and also cut the braid at the both ends of the PEEK tube. The length of the resulting packed section was 60 mm, while the total length of the stainless-steel wire was 160 mm. Fig. 4 shows an illustration of the extraction capillary. The total amount of Zylon filaments packed in the extraction tube was about 10.2 mg, and the packing density include the stainless-steel wire was calculated to be about 71.3%, where the packing density was calculated on the basis of total cross section of the filaments and the stainless-steel wire to the cross section of PEEK tube opening The void volume of the extraction capillary was about 3.4 μL. The sections of the extra 50 mm length each of the metal wire, at the both ends of the PEEK tube, were specially-designed for the electric connection to the power supply as illustrated in Fig. 5. All the tubing, the extraction capillary and the electric wiring were installed into a set of PTFE tee connectors (GL Sciences) with modifications to ensure to avoid any undesirable dead volume in the device. 2.4. LC System LC system was consisted of an 880-PU pump (Jasco, Tokyo, Japan), a model UV875 UV-Vis absorption detector (Jasco) and a Model 7125 injector (Rheodyne, Cotati, CA, USA) with a 40-μL loop. As a conventional octadecylsilica (ODS) analytical column, Wakopak Eco-ODS (4.6 mm i.d., 150 mm length, 5 μm particle size; Wako Pure Chemical Industries, Osaka, Japan) was used. The mobile phase was prepared with a mixture of methanol and water (85:15) and the typical flowrate was set at 1.0 mL/min. The detection was carried out using the above mentioned UV detector with the detection wavelength at 254 nm. All the LC runs were conducted at the room temperature controlled by an air conditioner at 23.5-24.5°C. For data acquisition and processing, Borwin Chromatography Software (Jasco) running on a personal computer was employed. All the measurements were carried out at least five times, and the relative standard deviations (RSDs) were less than 4.0% for all the chromatographic analyses. 2.5. Extraction and desorption procedure
8
Two syringe pumps (Microfeeder MF-2, Azuma Denki Kogyo, Tokyo, Japan) with a gas tight syringe (MS-GAN 100, Ito Corporation, Shizuoka, Japan) were employed for pumping the sample solution and desorption solvent to the extraction capillary. The extraction process was carried out by pumping 1.0 mL of an aqueous sample solution into the extraction device, and then the remaining solution inside the tubing was removed by passing 5.0 mL of air with a micro-syringe operated manually for about 30 sec. Next, desorption solvent was pumped at the flowrate of 20 μL/min. A model 7125 injector with a 40-μL loop was placed between the syringe pump and the extraction device for pumping of two organic solvents sequentially as described below. The eluate from the extraction capillary was collected by a conventional micro-syringe (100 μL volume; MS-R 100, Ito Corporation) for subsequent analysis in LC, where the needle of the micro-syringe was directly inserted into the outlet capillary of the extraction device. A conditioning procedure was carried out by passing 5.0 mL of methanol, 1.0 mL of water and 5.0 mL of air between runs. 3. Results and Discussion 3.1. Optimization of extraction flowrates For an effective extraction of the analyte, extraction flowrates of 40, 60, 80 and 120 μL/min were initially studied, where the sample volume of 1.0 mL was maintained. The results are summarized in Table 2. More than 90% of phenanthrene could be extracted in all the flowrate studied, where it was confirmed that the extraction efficiency was slightly increased at a slower flowrate. On the basis of the above results, additional intensive experiments was carried out, where the extraction flowrate of 20 μL/min was also considered. The results are the statistically the same as that obtained at 40 μL/min. In addition, it was also confirmed in this intensive experiments for the comparison of extraction flowrate of 40 and 60 μL/min. that the extraction efficiency at 40 μL/min is slightly better than that at 60 μL/min. Therefore, 40 μL/min was chosen as the optimum extraction flowrate
9
under the consideration of the total analysis time. 3.2. Optimization of desorption solvent Prior to the optimization of the desorption conditions, several typical organic solvents such as n-hexane, toluene, dichloromethane, acetone and methanol were investigated in the preliminary experiment, and a better desorption efficiency was observed with acetone as the desorption solvent. However, as can be expected from the results in our previous publications [28], a non-polar organic solvent has a better desorption capability than a polar organic solvent, for desorbing phenanthrene from Zylon, due to the surface characteristics. For the desorption of phenanthrene from the braid-type extraction medium, one can assume that a certain amount of water was still remain trapped in between the fine filaments when pumping a non-polar desorption solvent only.
Since the braid was consisted of bundles of fine filaments, the
configuration of these bundles could be regarded as quite complex compared with conventional fiber-packed extraction capillaries [12,13]. In contrast to the conventional fiber-packed capillary, where a bundles of filaments was packed longitudinally into the housing capillary, a different desorption process should be considered for an effective desorption from braid-type extraction medium. In this work, a sequential pumping process was introduced for the desorption step, where acetone was delivered first followed by n-hexane, allowing both an effective removal of water from the extraction tube by acetone and also an effective desorption of the extracted non-polar analyte by n-hexane. The sequential pumping procedure in the desorption process is shown in Fig. 6, where the loop in a six-port valve was filled with non-polar solvent (2nd desorption solvent) followed by a partial replacement with polar solvent (1st desorption solvent). The resulting set of desorption solvents, such as acetone and n-hexane in this order, was delivered to the extraction capillary. Table 3 summarizes the desorption efficiencies obtained with this sequential pumping procedure of two solvents, where the ratio between non-polar and polar solvents was
10
changed. The RSDs for five repeated runs are also in the table. Introducing the sequential pumping of two organic solvents, acetone and n-hexane, the desorption efficiency was significantly improved. The results suggest that the trace amount of water in the extraction capillary was effectively washed out with a plug of acetone in advance of the desorption of phenanthrene by n-hexane. On the basis of these results, the sequential pumping of acetone and n-hexane, 5 μL and 35 μL, respectively, was employed in the following experiments. 3.3. Thermal desorption For further improving the desorption efficiency, thermal desorption was studied. As described in the previous section, the extraction tube has a specially-designed configuration that is well-compatible to resistive heating during the desorption process. Surface temperature of the extraction device during the thermal desorption process was observed by employing thermographic camera (FLIR i7, FLIR Systems, Wilsonville, OR, USA). With a laboratory-made power supply, a programmable application of an AC voltage was carried out. Based on the systematic consideration in the preliminary experiments, the voltage application program was set as: the application of the voltage for 3 s followed by no application time for 27 s. The application voltage and the application program were adjusted in the range not to evaporate the desorption solvents in the tubing. For the desorption of the extracted analyte from the extraction capillary, the above voltage application program was repeated four times with a flow of desorption solvent at 20 μL/min for two min, allowing the delivery of 40-μL desorption solvent through the extraction capillary under an elevated temperature by resistive heating. Fig. 7 shows typical thermographic picture during the resistive heating and the corresponding desorption efficiencies with changing the applied voltage were summarized in Table 4. Compared with the desorption without voltage application, the desorption was significantly effective when a few volts were applied to the stainless-
11
steel wire in the extraction capillary, and the analyte were completely desorbed only with a low applied voltage at 2V or 3V. In Fig. 8, a comparison of the chromatograms of phenanthrene obtained with and without sample preparation process developed in this work. In the optimized conditions, the LOQ and the LOD for phenanthrene were 0.048 and 0.014 μg/mL, respectively, where the entire recovery was 96.6% with the RSD of less than 3.0% (n=5). More than 100 runs could be performed without any significant problems such as a decrease in the extraction power, suggesting a good stability for repeatable use of the miniaturized sample preparation device developed in this work. 4. Conclusions Introducing a braid-type fiber-packed capillary, a new miniaturized sample preparation device was developed. The extraction conditions were systematically optimized, and the efficient extraction was confirmed under the optimized conditions with a sequential delivery of two organic solvents. With the application of a low voltage to the metal wire included in the extraction device, an experimentally complete desorption was achieved for phenanthrene in water samples. Although a more systematic investigation must be made, the unique configuration of the extraction cartridge could be regarded as one of the most promising technique in the miniaturized sample preparation, and a wide range of applications could be expected in the near future. A promising possibility of this wire-in-braid configuration is expected especially for the use as a novel interface or modulator of two-dimensional chromatographic separations [35-41]. Surface-polymercoated [13,24] or surface-modified fibrous materials [26,42] could also be employed to enhance the particular selectivity to a certain class of compounds.
12
Acknowledgements A part of this study was financially supported by JSPS KAKENHI (Grant Number 18K05169).
KN and OS acknowledge the support from Toyohashi University of
Technology. The authors would like to thank Mr. Y. Nomura of Toyobo for his valuable technical advice.
13
References [1]
M. Tada, Comprehensive Treatise of Braids I: Maru-dai braids, first ed., Texte, Inc., Tokyo, 1996.
[2]
E. Tanaka, M. Terada, T. Nakamura, S. Misawa, C. Wakasugi, Forensic analysis of eleven cyclic antidepressants in human biological samples using a new reversed-phase chromatographic column of 2 μm porous microspherical silica gel, J. Chromatogr. B, 692 (1997) 405-412. https://doi.org/10.1016/S03784347(96)00510-5.
[3]
P. Ghahramani, M.S. Lennard, Quantitative analysis of amitriptyline and nortriptyline in human plasma and liver microsomal preparations by highperformance liquid chromatography, J. Chromatogr. B, 685 (1996) 307-313. https://doi.org/10.1016/S0378-4347(96)00193-4.
[4]
G. Aymard, P. Livi, Y.T. Pham, B. Diquet, Sensitive and rapid method for the simultaneous quantification of five antidepressants with their respective metabolites in plasma using high-performance liquid chromatography with diode-array
detection,
J.
Chromatogr.
B,
700
(1997)
183-189.
https://doi.org/10.1016/S0378-4347(97)00327-7. [5]
E. Baltussen, C.A. Cramers, P.J.F. Sandra, Sorptive sample preparation - a review, Anal. Bioanal. Chem., 373 (2002) 3-22. https://doi.org/10.1007/s00216-0021266-2.
[6]
S.H. Salleh, Y. Saito, K. Jinno, An approach to solventless sample preparation procedure
for
pesticides
analysis
using
solid
phase
microextraction/supercritical fluid extraction technique, Anal. Chim. Acta, 418 (2000) 69-77. https://doi.org/10.1016/S0003-2670(00)00944-2. [7]
Y. Saito, A. Tahara, M. Imaizumi, T. Takeichi, H. Wada, K. Jinno, Polymer-coated fibrous materials as the stationary phase in packed capillary gas chromatography,
Anal.
Chem.,
14
75
(2003)
5525-5531.
https://doi.org/10.1021/ac030052h. [8]
Y. Saito, M. Ogawa, M. Imaizumi, K. Ban, A. Abe, T. Takeichi, H. Wada, K. Jinno, High-temperature separation with polymer-coated fiber in packed capillary gas chromatography,
Anal.
Bioanal.
Chem.,
382
(2005)
825-829.
https://doi.org/10.1007/s00216-004-2967-5. [9]
Y. Saito, M. Imaizumi, K. Nakata, T. Takeichi, K. Kotera, H. Wada, K. Jinno, Fibrous rigid-rod heterocyclic polymer as the stationary phase in packed capillary gas chromatography,
J.
Microcol.
Sep.,
13
(2001)
259-264.
https://doi.org/10.1002/mcs.10005. [10]
Y. Saito, K. Jinno, Miniaturized sample preparation combined with liquid phase separations,
J.
Chromatogr.
A,
1000
(2003)
53-67.
https://doi.org/10.1016/S0021-9673(03)00307-8. [11]
Y. Bu, J. Feng, M. Sun, C. Zhou, C. Luo, Facile and efficient poly(ethylene terephthalate) fibers-in-tube for online solid-phase microextraction towards polycyclic aromatic hydrocarbons, Anal. Bioanal. Chem., 408 (2016) 48714882. https://doi.org/10.1007/s00216-016-9567-z.
[12]
K. Jinno, M. Ogawa, I. Ueta, Y. Saito, Miniaturized sample preparation using a fiber-packed capillary as the medium, Trends Anal. Chem., 26 (2007) 27-35. https://doi.org/10.1016/j.trac.2006.11.008.
[13]
Y. Saito, M. Nojiri, M. Imaizumi, Y. Nakao, Y. Morishima, H. Kanehara, H. Matsuura, K. Kotera, H. Wada, K. Jinno, Polymer-coated synthetic fibers designed for miniaturized sample preparation process, J. Chromatogr. A, 975 (2002) 105-112. https://doi.org/10.1016/S0021-9673(02)01333-X.
[14]
M. Imaizumi, Y. Saito, K. Ban, H. Wada, M. Hayashida, K. Jinno, In-valve sample preparation cartridge designed for microcolumn liquid chromatography, Chromatographia, 60 (2004) 619-623. https://doi.org/10.1365/s10337-0040428-0.
15
[15]
M. Ogawa, Y. Saito, I. Ueta, K. Jinno, Fiber-packed needle for dynamic extraction of aromatic compounds, Anal. Bioanal. Chem., 388 (2007) 619-625. https://doi.org/10.1007/s00216-007-1255-6.
[16]
M. Ogawa, Y. Saito, S. Shirai, Y. Kiso, K. Jinno, Determination of Bisphenol A in water using a packed needle extraction device, Chromatographia, 69 (2009) 685-690. https://doi.org/10.1365/s10337-008-0928-4.
[17]
I. Ueta, Y. Saito, N.B.A. Ghani, M. Ogawa, K. Yogo, A. Abe, S. Shirai, K. Jinno, Rapid determination of ethylene oxide with fiber-packed sample preparation needle, J.
Chromatogr.
A,
1216
(2009)
2848-2853.
https://doi.org/10.1016/j.chroma.2008.10.107. [18]
I. Ueta, Y. Saito, Needle-type extraction device designed for rapid and sensitive analysis
in
gas
chromatography,
Anal.
Sci.,
30
(2014)
105-110.
https://doi.org/10.2116/analsci.30.105. [19]
A. Gutiérrez-Serpa, D. Schorn-García, F. Jiménez-Moreno, A.I. JiménezAbizanda, V. Pino, Braid solid-phase microextraction of polycyclic aromatic hydrocarbons by using fibers coated with silver-based nanomaterials in combination with HPLC with fluorometric detection, Microchim. Acta, 186 (2019) 311. https://doi.org/10.1007/s00604-019-3452-3.
[20]
R.D. Stanelle, M. Mignanelli, P. Brown, R.K. Marcus, Capillary-channeled polymer (C-CP) fibers as a stationary phase in microbore high-performance liquid chromatography columns, Anal. Bioanal. Chem., 384 (2006) 250-258. https://doi.org/10.1007/s00216-005-0117-3.
[21]
D.K. Nelson, R.K. Marcus, A novel stationary phase: Capillary-channeled polymer (C-CP) fibers for HPLC separations of proteins, J. Chromatogr. Sci., 41 (2003) 475-479. https://doi.org/10.1093/chromsci/41.9.475.
[22]
R.K. Marcus, W.C. Davis, B.C. Knippel, L. LaMotte, T.A. Hill, D. Perahia, J.D. Jenkins, Capillary-channeled polymer fibers as stationary phases in liquid
16
chromatography
separations,
J.
Chromatogr.
A,
986
(2003)
17-31.
https://doi.org/10.1016/S0021-9673(02)01835-6. [23]
M. Ogawa, Y. Saito, M. Imaizumi, H. Wada, K. Jinno, Longitudinal miniaturization of fiber-packed capillary column in high temperature gas chromatography, Chromatographia, 63 (2006) 459-463. https://doi.org/10.1365/s10337-0060771-4.
[24]
Y. Saito, A. Tahara, M. Ogawa, M. Imaizumi, K. Ban, H. Wada, K. Jinno, Polymer-coated
fibrous
chromatography,
stationary
Anal.
phase
Sci.,
in
20
packed-capillary (2004)
gas
335-339.
https://doi.org/10.2116/analsci.20.335. [25]
Y. Saito, M. Ogawa, M. Imaizumi, K. Ban, A. Abe, T. Takeichi, H. Wada, K. Jinno, Short metal capillary columns packed with polymer-coated fibrous materials in high-temperature gas chromatography, J. Chromatogr. Sci., 43 (2005) 536-541. https://doi.org/10.1093/chromsci/43.10.536.
[26]
A. Abe, Y. Saito, M. Imaizumi, M. Ogawa, T. Takeichi, K. Jinno, Surface derivatization of poly(p-phenylene terephthalamide) fiber designed for novel separation and extraction media, J. Sep. Sci., 28 (2005) 2413-2418. https://doi.org/10.1002/jssc.200401938.
[27]
S.H. Salleh, Y. Saito, K. Jinno, Solventless sample preparation procedure for organophosphorus pesticides analysis using solid phase microextraction and on-line supercritical fluid extraction/high performance liquid chromatography technique,
Anal.
Chim.
Acta,
433
(2001)
207-215.
https://doi.org/10.1016/S0003-2670(01)00790-5. [28]
Y. Saito, M. Imaizumi, T. Takeichi, K. Jinno, Miniaturized fiber-in-tube solidphase extraction as the sample preconcentration method for microcolumn liquid-phase separations, Anal. Bioanal. Chem., 372 (2002) 164-168. https://doi.org/10.1007/s00216-001-1126-5.
17
[29]
Y. Saito, Y. Nakao, M. Imaizumi, Y. Morishima, Y. Kiso, K. Jinno, Miniaturized solid-phase extraction as a sample preparation technique for the determination of
phthalates
in
water,
Anal.
Bioanal.
Chem.,
373
(2002)
81-86.
https://doi.org/10.1007/s00216-002-1270-6. [30]
B. Riahi-Zanjani, M. Balali-Mood, A. Asoodeh, Z. Es’haghi, A. GhoraniAzam, Developing a new sensitive solid-phase microextraction fiber based on carbon nanotubes for preconcentration of morphine, Appl. Nanosci., 8 (2018) 2047-2056. https://doi.org/10.1007/s13204-018-0882-x.
[31]
S.X.L. Goha, H.K. Lee, An alternative perspective of hollow fiber-mediated extraction: Bundled hollow fiber array-liquid-phase microextraction with sonication-assisted desorption and liquid chromatography-tandem mass spectrometry for determination of estrogens in aqueous matrices, J. Chromatogr.
A,
1488
(2017)
26-36.
http://dx.doi.org/10.1016/j.chroma.2017.01.081. [32]
J. Pawliszyn (Ed.), Applications of Solid Phase Microextraction, Royal Society of Chemistry, Letchworth, 1999.
[33]
J. Pawliszyn, H.L. Lord (Eds.), Handbook of Sample Preparation, John Wiley & Sons, Hoboken, 2010.
[34]
Y. Saito, M. Imaizumi, K. Ban, A. Tahara, H. Wada, K. Jinno, Development of miniaturized sample preparation with fibrous extraction media, J. Chromatogr. A, 1025 (2004) 27-32. https://doi.org/10.1016/j.chroma.2003.08.098.
[35]
D. Ryan, P. Marriott, Comprehensive two-dimensional gas chromatography, Anal. Bioanal. Chem., 376 (2003) 295–297. https://doi.org/10.1007/s00216003-1934-x.
[36]
J. Harynuk, T. Gorecki, New liquid nitrogen cryogenic modulator for comprehensive two-dimensional gas chromatography, J. Chromatogr. A, 1019 (2003) 53–63. https://doi.org/10.1016/j.chroma.2003.08.097.
18
[37]
F. Begnaud, C. Debonneville, J.-P. Probst, A. Chaintreau, P.D. Morrison, J.L. Adcock, P.J. Marriott, Effects of variation in modulator temperature during cryogenic modulation in comprehensive two-dimensional gas chromatography, J. Sep. Sci. 32 (2009) 3144–3151. https://doi.org/10.1002/jssc.200900290.
[38]
P.Q. Tranchida, M. Zoccali, F.A. Franchina, A. Cotroneo, P. Dugo, L. Mondello, Gas velocity at the point of re-injection: An additional parameter in comprehensive two-dimensional gas chromatography optimization, J. Chromatogr. A, 1314 (2013) 216–223. http://dx.doi.org/10.1016/j.chroma.2013.09.025.
[39]
P.Q. Tranchida, F.A. Franchina, M. Zoccali, I. Bonaccorsi, F. Cacciola, L. Mondello, A direct sensitivity comparison between flow-modulated comprehensive 2D and 1D GC in untargeted and targeted MS-based experiments, J. Sep. Sci. 36 (2013) 2746–2752. https://doi.org/10.1002/jssc.201300423.
[40]
H.D. Bahaghighat, C.E. Freye, D.V. Gough, P.E. Sudol, R.E. Synovec, Ultrafast separations via pulse flow valve modulation to enable high peak capacity multidimensional gas chromatography, J. Chromatogr. A, 1573 (2018) 115–124. https://doi.org/10.1016/j.chroma.2018.08.001.
[41]
H.D. Bahaghighat, C.E. Freye, D.V. Gough, R.E. Synovec, Comprehensive twodimensional gas chromatography and time-of-flight mass spectrometry detection with a 50 ms modulation period, J. Chromatogr. A, 1583 (2019) 117– 123. https://doi.org/10.1016/j.chroma.2018.11.027.
[42]
S. Shirai, Y. Saito, Y. Sakurai, I. Ueta, K. Jinno, Retention behavior on aminoethyl-modified poly(p-phenylene terephthalamide) fiber stationary phases in gas chromatography, Anal. Sci. 26 (2010) 1011-1014. https://doi.org/10.2116/analsci.26.1011.
19
Figure Captions
20
Figure 1. A laboratory-made set-up for the preparation of braided fiber. (A) Center weight; (B) bobbins; (C) stainless-steel wire.
21
Figure 2. Preparation of braid-type extraction medium. Bobbin positions (a)-(d) correspond that in Fig. 1. First, i) a pair of bundles placed at the opposite of the circular plate (a and c) were simultaneously moved clockwise 180°, and then, ii) another pair of bundles (b and d) were also simultaneously moved counterclockwise 180°. This twostep process was repeated once more as shown in iii) and iv), to return to the original configuration i).
22
Figure 3. Typical photograph of a braided fiber prepared in this work.
23
Figure 4. Schematic of the braid-packed extraction capillary with a stainless-steel wire therein.
Figure 5. Illustration of the miniaturized SPE device connected with an electric power supply developed in this work. .
24
Figure 6. Scheme of the sequential pumping procedure with two types of organic solvents. (A) Fill the sample loop of the injection valve with the 2nd desorption solvent, (B) switch the injection valve, and inject certain volume of 1st desorption solvent, where a small volume of air was inserted between section of the 2nd and 1st desorption solvents, (C) switch the valve again, and start the sequential pumping of two desorption solvents.
25
Figure 7. Thermographic observation of the surface temperature of the extraction capillary during a resistive heating process. Applied voltage: (A) 0V, (B) 1V, (C), 2V and (D) 3V. Other conditions are in the text.
26
Figure 8.
Comparison of chromatograms observed for (a) the sample solution
preconcentrated
by
the
miniaturized
SPE
device,
and
(b)
that
without
preconcentration. Extraction conditions: extraction flowrate, 40 μL/min; extraction volume, 1.0 mL; concentration of phenanthrene standard, 1.0 μg/mL. Desorption conditions: desorption flowrate, 20 μL/min; desorption solvent volume, 40 μL; desorption solvent and volume, acetone 5 μL + n-hexane 35 μL. Thermal desorption condition: applied voltage, 2V; voltage was applied continuously while desorption process. LC conditions: mobile phase, methanol/water = (85/15); flowrate, 1.0 mL/min; detection, UV at 254 nm.
27
Table 1. Various types of braids and the corresponding extraction capillaries prepared in this work. braid entr y 1 2 3 4 5
o.d. of stainlesssteel wire (mm) 0.2 0.2 0.1 0.1 0.1
extraction capillary
center weight (g)
o.d. of braid (mm)
void volume (µL)
packing density (%)
100 200 100 200 300
0.51 0.48 0.47 0.43 0.39
3.38 4.85 5.64 6.32 6.78
71.3 58.9 52.1 46.3 42.5
28
40 60 80 120
Table 2. Comparison of extraction flowrates. extraction flowrate extraction efficiency (%) (µL/min) 96.0 94.2 90.8 90.1
29
Table 3. Comparison of desorption solvent. desorption solvent volume desorption efficiency (%) (acetone + n-hexane) 40 μL + 0 μL 68.4 20 μL + 20 μL 78.0 10 μL + 30 μL 83.7 5 μL + 35 μL 87.5 0 μL + 40 μL 22.7
30
RSD (%) 2.5 3.7 2.7 0.6 3.5
Table 4. Surface temperature of the extraction capillary and the desorption efficiency with thermal desorption at different applied voltages. surface temperature applied voltage (V) desorption efficiency (%) RSD (%) of capillary tube (ºC) 0 22 87.5 0.6 1 26 95.0 1.2 2 35 100.6 1.3 3 44 99.4 2.1
31