Multiresidue method for the determination of pesticides in Oolong tea using QuEChERS by gas chromatography-triple quadrupole tandem mass spectrometry

Accepted Manuscript Multiresidue method for the determination of pesticides in Oolong tea using QuEChERS by gas chromatography–triple quadrupole tandem mass spectrometry Chia-Chang Wu PII: DOI: Reference:

S0308-8146(17)30283-2 http://dx.doi.org/10.1016/j.foodchem.2017.02.081 FOCH 20634

To appear in:

Food Chemistry

Received Date: Revised Date: Accepted Date:

29 March 2016 2 September 2016 16 February 2017

Please cite this article as: Wu, C-C., Multiresidue method for the determination of pesticides in Oolong tea using QuEChERS by gas chromatography–triple quadrupole tandem mass spectrometry, Food Chemistry (2017), doi: http://dx.doi.org/10.1016/j.foodchem.2017.02.081

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Multiresidue method for the determination of pesticides in Oolong tea using QuEChERS by gas chromatography–triple quadrupole tandem mass spectrometry Chia-Chang Wu*

Abstract: We propose a simple, rapid analytical method for determination of 89 pesticides in Oolong tea by GC/MS/MS. Samples were extracted via QuEChERS. The limits of detection and quantification range of the 89 pesticides were 1 to 25 µg L-1and 10 to 50 µg L-1, respectively. Good separation was attained in less than 36 min. A wide linear range of 1- 250 µg L-1 was observed with r2 values from 0.9955-0.9998. Pesticide-free tea powder spiked at 50 and 100 µg L-1. Recovery ranges of the 86 (50 µg L-1) and 83 (100 µg L-1) pesticides were from 60% to 120%. Relative standard deviations were less than 20%. The laboratory proficiency test (FAPAS, 2014) shows satisfactory (|z| < 2) z-score values. The proposed monitoring technique rapidly and efficiently screens, multiple pesticides in Oolong tea. Key words: Oolong tea, QuEChERS, GC/MS/MS, Pesticide residues

* Corresponding author.

Address: Tea Research and Extension Station, Taoyuan 326,

Taiwan, R.O.C.; Tel: +886 34822059, Fax: +886 34822059; E-mail: [email protected]

1 Introduction "Food safety" has become the subject of popular interest in recent years, especially with the endless stream of incidents related to pesticide residue in foods or crops which have caused consumer panic. In order to ensure consumer health, research and development institutions in many countries have begun to analyze 1

pesticide residues in agricultural products and monitor the safety of agricultural products (Luke et al., 1983). In Taiwan, the Tea Research and Extension Station also conduct tests to evaluate the safe usage of tea pesticides (Wu, 2001). Conventional sample extraction methods for pesticide residues in agricultural products include solid-phase extraction (Economou et al. , 2009 ; Wu et al. , 2009), ultrasonic-assisted extraction (Wang & Curtis, 2006), accelerated solvent extraction (Lehotay & Eller, 1995), soxhlet extraction (Luke et al., 1983), and gel permeation chromatography (Tekel & Hatrik, 1996). However, the above methods required many amounts of solvents and very labor intensive, while offering poor recovery rates. In addition, they generate large amounts of waste may cause lead to human toxicity and carcinogenicity, and treatment of the wasted liquid is expensive and polluting. Thus, it is necessary to develop low-solvent or solvent-free techniques for pretreatment in pesticide analysis. At the European Pesticide Residue Workshop in 2002, scientists developed a simplifying sample pretreatment method for pesticide analysis in food called QuEChERS (pronounced “Quichers”), which is an acronym for Quick, Easy, Cheap, Effective, Rugged and Safe. The above method is a fast-growing sample extraction and cleanup procedure for analyzing pesticide residues in agricultural products. Therefore, the QuEChERS method has been established as the AOAC Official draft law and the United States Department of Agriculture has carried out 20 kinds of pesticides and 3 kinds of inspection bodies (grapes, lettuces, and citrus) for collaborative study. These efforts have led to better results (Anastassiades et al., 2003). Moreover, the European Union has approved the QuEChERS method as a standard method of analysis (European Standard EN 15662:2008., 2008). As for its analysis features, QuEChERS uses an inspection body with little solvent extraction. 2

Without multiple extraction processes, a concentrator, constant volume or the usual pesticide residue analysis steps, this method significantly reduces processing time and increases the varieties of pesticide analysis. The QuEChERS method has been widely used in the European Union and the United States for pesticide residue analysis of vegetables and fruits (Elham et al., 2016; Tesfa et al., 2016). Tea is a popular drink throughout the world, and in recent years, consumers have become more and more concerned about the presence of pesticide residues in tea, Therefore investigation of pesticide residues in tea is an important issue (Shivani et al., 2001; Wu, 2001). The Tea Research and Extension Station is a governmental laboratory which has conducted tests to evaluate the safe usage of pesticides in Taiwan since 1985 (Wu et al., 2012). Starting in 1985, we have developed methods by using solvent extraction and gas chromatography with electron-capture detector and flame-phosphorus detector (GC /ECD/FPD), liquid chromatography with dluorescence detector (LC/FLD) and liquid chromatography---triple quadrupole tandem mass spectrometry (LC/MS/MS) to analyze pesticide residues in fresh tea leaves, ready-made tea and tea brews (Wu, 2001; Wu, 2003; Wu et al., 2007; Lin et al., 2008; Wu et al., 2009; Wu et al., 2010). The problem is that the matrix of tea is highly complex, because tea contains protein, polyphenolic compounds, sugars, alkaloids, pigments and other substances. During the solvent extraction process for the analysis of pesticide residues, many complex chemical substances are seized and co-extracted. This leads to interference problems, and affects the detection limit. Extraction, vacuum concentration and purification treatments can be used to resolve the matrix interference problems, but these methods increase the amount of solvent used and the processing time. Liquid and gas chromatography are applied for multi-residue pesticide analysis for decades. Since people are getting more concerned about food safety issue, the 3

Government established lower and lower tolerances in regulations. Therefore, it is necessary to adopt liquid or gas chromatography-tandem mass spectrometry detection to improve the selectivity and accuracy of results in the qualitative and quantitative. For the past ten years, LC/MS/MS workflow is well established, but GC/MS/MS is still developing. The aim of this paper is to optimize and validate the QuEChERS extraction method followed by GC/MS/MS simultaneous determination of pesticide residues in tea.

2 Experimental 2.1 Reagents, chemicals and materials A total of 89 standard pesticides with purity ranging from 98.6 % to 99.9% were purchased from Accu Standard (New Haven, USA), Chem Service Company (PA, USA), Dr. Ehrenstorfer Company (Augsburg, Germany), Fluka Company (Steinheim, Germany), Merck Companies (Germany), and Riedel de-Haën (Hannover, Germany), Wako (Richmond, USA). All the solvents and chemicals used in the experiment were analytical grade and were purchased from Merck (Germany). Primary secondary amine (PSA), graphitized carbon black (GCB), and SampliQ extraction tube (packed with sodium acetate anhydrous, 1.5g, and anhydrous magnesium sulfate, 6g, with 50ml plastic centrifuge tubes) were purchased from Agilent Company (CA, USA). 2.2. Extraction studies We applied 4 g of Oolong tea powder added to a 50 mL centrifuge tube with 16 mL distilled water and left to stand for 20 minutes. The samples were then extracted with 10 mL acetonitrile (containing 1% acid), shook for 30 seconds, and put in a QuEChERS extraction package (packed with 1.5g anhydrous sodium acetate and 6g anhydrous magnesium sulfate, Agilent SampliQ extraction tube, AOAC Met (PN. 5982-5755) and shook for 1 minute, with 3500 rpm centrifugal force for 10 minutes. 4

We then cleaned up the upper 4 mL extraction solvent with a florisil cartridge (J. T. Baker, USA), and evaporated to dryness with nitrogen gas. The residue was then dissolved in a 1 mL acetone- N-hexane (1/1 (v/v)) and passed through 0.2 µm m membrane filters before GC/MS/MS injection (Fig. 1). 2.3 2.3 . Analytical instruments and conditions We applied gas chromatograph (Agilent Technologies 6890, USA) with tandem mass spectrometry (Agilent GC / 7000A GC/MS triple quadrupole), equipped with a HP-5MS column (AgilentHP-5MS,3000 mm × 0.25 mm, 0.25 μm)

for pesticides

separation. The gradient analysis of the gas chromatograph was as follows: temperature 70°C, maintain temperature rising rate of 25 °C /min to 150°C for 2 min, temperature rising rate of 3 °C/min to 200°C, a temperature rising rate 8 °C /min, and an end temperature 280°C, maintained 10 min. Tandem mass spectrometer component operation conditions setting were as follows: the temperature ion source was 230 °C, the quadrupole temperature was 150°C, the mass spectrometer and gas chromatograph in the line of the junction (transfer line) temperatures were 280℃, the ionization energy was 70 eV, and the carry gas and all the gas in the colliding room were helium. Using the multiple reaction monitoring mode (MRM) to scan the ions, we set the retention time (RT), fragment voltage and collision energy. 2.4 2.4 . Calibration, limits of detection and quantification A standard stock solution (1000µg L-1) was prepared in acetonitrile and stored at -20°C. The working solutions required for preparing a standard curve (1, 2.5, 5,10,25,50,100 and 250µg L-1) in pesticide-free tea powders for matrix-matched were obtained. All measurements were performed in triplicate for each level and 10 µL of solution was injected into the mass spectrometer for analysis. Calibration curves were calculated by linear least-squares regression using peak areas. Based on their concentrations, x axis, peak area, and y axis, which were obtained by regression 5

analysis of standard inspection lines: y= a + bx, and a and b are constant. The coefficient of determination of r2 must be greater than 0.99. 2.5 2.5 . Recovery studies During recovery studies, the 4 g pesticide-free tea powder samples which spiked -1

at 50 and 100 µgg L pesticide levels were used for fortification analysis to evaluate the recovery (%) and determine the relative standard deviation (RSD) of 89 pesticides. The recovery assays were replicated three times.

3 Results and Discussion 3.1 Optimization of GC/MS/ GC/MS/MS conditions In our study, a total of 89 pesticides used for common tea plants, vegetables, fruits and rice were selected for investigation, such as organ phosphorus pesticides, organic chlorine pesticides, organic nitrogen pesticides, heterocyclic compounds, and synthetic insecticides were used to establish the MRM for GC/MS/MS. Table 1 summarizes the optimized GC/MS/MS MRM acquisition parameters of the targeted pesticides. We established a parent ion scan mode, with a scanning range from 50 to 550 (m/z). Next, we selected the precursor ion of 89 pesticides for the second collision of ions with different voltages. Then we selected a signal value and the highest percentage collision value of the two ions and voltages. Finally, we determined the highest value for the quantitative ion, followed by the qualitative ion. The qualitative ion collision voltage range for the 89 pesticides was 5-35 (eV) and the quantitative ion collision cover range was 5-40 (eV). In order to avoid RT variation of the pesticides, we added pesticides to the tea matrix, and then changed the GC/MS/MS pressure to stabilize the retention time of the chromatography of the target compounds, and ensure the retention times of the 89 pesticides were within the allowed range (± 0.05 sec). As Table 1 indicates, the analysis chromatogram of the 6

first material which appeared was propoxur with an RT of 10.36 min, qualitative ion of 110.00>63.00 (m/z), collision voltage of 30 (eV), quantitative ion of 110.00>64.00 (m/z), and collisions voltage of 20 (eV). The latest material, deltamethrinat, occurred with an RT of 35.94 min, qualitative ion of 253.00>93.00 (m/z), collision voltage of 22 (eV), quantitative ion of 253.00>174.00 (m/z), and collisions voltage of 10 (eV). Figure 2 showed chromatograms of the separation for 89 analyses in standard solution of pesticides. Working on the stated model of multiple reactions for monitoring mass spectrometry analysis of pesticides, we obtained a good separation in a relatively short time (42 min), without interference with the matrix. In this study, we also selected the two transition ions to be detected. The selected ions contained 1 precursor (1 IP) and 2 precursors (1.5x2=3IPs), with a total of 4 IPs received, in line with the EU 2002/657/EC (Commission Decision 2002/657/EC., 2002.) analysis of the specification. Thus, we can be fairly certain that this method is effective in identifying pesticide residues in tea samples (European Commission. Document No SANCO/2007/1331., 2007). 3.2 3.2 MatrixMatrix -matched calibration curve In order to reduce the effect of the matrix on quantitative determination, and improve the accuracy of real samples of concentration, we added a series of working solutions ranging from 5-250µg g L-1 in pesticide-free Oolong tea powders to create a matrix-matched calibration curve. With the accurate preparation of the known purity standards of pesticide products, the pesticides were prepared with acetone/N-hexane -1

(1/1, v/v) in 10µgg L as a stock solution. Avoiding light, the samples were stored at -20°C. We then took a suitable amount of a standard liquid mixture, and gradually diluted the working solution at a low concentration to obtain the working solution. We -1

used acetone /N-hexane (1/1, v/v) diluted to 1, 2.5, 5, 10, 25, 50, 100 and 250μg L as a mixed standard solution. 7

Calibration curves were calculated by linear least-squares regression using peak areas. Based on their concentrations, the x axes, peak areas and y axes were obtained by regression analysis of standard inspection lines: y= a + bx, and a and b are constant for the intercept and the slope, respectably. The linear concentrations of the 89 -1

pesticides range from 1- 250 µgg L . 2

2

The results of the linear correlation coefficient (r ) are shown in Table 2. The r of 89 pesticides ranged from 0.995 - 0.999, except bifenox (r2 = 0.985). In this study, the r2 of bifenox was less than 0.99, it might be due to that bifenox (C14H9Cl2NO5) contain relatively polar groups are susceptible to matrix effect. Table 2 shows that the analysis of pesticide residues in tea by the GC/MS/MS obtained good qualitative and quantitative analysis of the results. 3.3 3.3 Limits of detection (LODs (LODs ) and limits of quantification (LOQs (LOQs ) To prepare the homogeneous pesticide-free Oolong tea powders, we added a -1

mixed standard solution of pesticides containing 1 - 100 µgg L in the inspection sample. Instrumental analyses of the target compounds were conducted 3 and 10 times to obtain the signal to noise ratio for the LODs and LOQs, respectively (SANCO/10476/2003., 2004). The LODs and LOQs were calculated using the following relations: LOD=X+3s, LOQ=X+10s, in which,”X” is the mean concentration of spiked sample blank values, and “s” is the sample standard deviation. The 89 pesticides mixed using the standard solution were added to pesticide-free Oolong tea powders. This was repeated 3 times with different concentrations. Results -1

showed that for the 89 pesticides, the LODs and LOQs ranged from 1 to 25µg g L and 10 to 50µgg L-1, respectively. Table 2 shows 70 pesticides had LODs at 1µg g L-1, accounting for a total of 78.65%. The LODs of cyfluthrin and diniconazole were 25 -1

-1

and 10µg g L , respectively. As for the LOQs, cyfluthrin had 50µgg L , but for -1

β -endosulfan and diniconazole, the LOQs were 20µgg L . The LOQs of 86 pesticides 8

-1

were at 10µg g L , making up a total of 96.63%. It is quite conceivable that the LOQs of most of the pesticides reach up to 10µgg L-1, and that the qualitative ion and quantitative ion ratio meet the identification requirements of the European Union (SANCO/10476/2003., 2004). The results show that using GC/MS/MS to analyze the pesticide residues in tea produced good quantitative detection limit findings. In addition, the LODs of the analysis data of quantitative limits are lower than the maximum residue limits (MRLs) of Taiwan, Japan, or the European Union, with maximum residue limits ranging from 1 to 10%. Therefore, the established GC/MS/MS analysis method is worth using for routine analysis of pesticide residues in tea. 3.4 3.4 Evaluation of the QuEChERS method The QuEChERS extraction method is quite mature when it comes to the inspection of vegetables and fruit, but due to the high complexity of the tea matrix, many complex chemical substances are extracted at the same time, causing interference and pesticides analysis, and seriously affecting the detection limits. Most QuEChERS extraction methods are sufficient for LC/MS/MS analysis, but few papers focused on GC/MS/MS analysis in order to reduce the matrix interference. Thus, in this study, we used applied the above approach for the clean-up and the concentration processes. To ensure the accuracy and the precision of experimental data, at the time of each analysis process, we added a solvent blank and recovery analysis. The solvent blank showed no signal interference, indicating that the analysis process is pollution-free. In the recovery experiments, we added different concentrations of mixed standard agents to pesticide-free Oolong tea powder, at concentrations of 50,100 µgg -1

L . At each concentration level, three analyses were performed. -1

According to the results, with a 50 µgL gL concentration in the tea sample, a total of 9

86 kinds of pesticides showed recovery results ranging from 60% to 120%, 3 kinds of pesticides had recovery values between 50% and 60%. Cyfluthrin had a recovery value of 134.5%, with an RSD value of 5.8%. Heptachlor had a recovery value of 57.8%, with an RSD value of 20.68%. And mirex had a recovery value of 57.8%, with an RSD value of 8%. -1

When the concentration was 100µgL gL in the tea sample, a total of 83 kinds of pesticides had recovery values from 60% to 120%, 1 kind of pesticide had a recovery value between 120% and 130%, and 5 kinds of pesticides showed recovery values between 50% and 60%. For bifenox, the recovery value was 129.4%, with an RSD of 8%. For heptachlor, the recovery value with 53.2%, with an RSD of 2.5%. Mirex had a recovery value of 52.7%, with an RSD of 8%. Propoxur showed a recovery value of 57.4%, with an RSD of 6.7%. Parathion-methyl had a recovery value of 57.7%, with an RSD of 7.2%. Results indicated that under three concentrations, the recovery values of the tea samples ranged from 53 to 129.4%, with all RSD values being lower than 20.86%. According to the current EU guidelines for quality control in pesticide residue analysis (SANCO/10232/2006,2006), the recovery obtained during routine analysis should be within 60-140%. From the results obtained, the QuEChERS extraction method can be considered acceptable for residue analysis in tea samples. To confirm the accuracy of this method, we evaluated it externally by participating in the laboratories proficiency test (PT No. 19162) for pesticide residue analysis of tea organized by FAPAS (http://www.fapas.-com) in 2014. The target compounds, including bifenthrin, chlorpyrifos, cyhalothrin, p,p’-DDE, covered by the proficiency test were properly identified and the respective z-score values obtained were -0.7, 0.1,-0.2,-0.1,-1.5, respectively. The z-score values obtained were satisfactory (|z| < 2), clearly showing good quantitative data were consistently 10

obtained by the proposed method.

Conclusions The modified QuEChERS method has been evaluated for Oolong tea sample preparation. We also optimized the operation parameters and evaluated the performance characteristics of GC/MS/MS for the analysis of 89 pesticides. From an analytical point of view, we compared the tea sample pesticide residue extraction method by modifying CNS 13570-2 liquid extraction method in our laboratory (Wu,2003; Wu et al., 2009). Considering the use of reagents and equipment, tea sample pesticide residues extraction method by modifying CNS 13570-2 method has a high cost, requires between 10 min to process a sample and require more than 200 mL amounts of expensive organic solvents. The development of the modified QuEChERS extraction method requires between 5 min processing a sample and requiring less than 20 mL amounts of organic solvents. Compared with traditional method the modified QuEChERS method has proven to be fast, easy to conduct, and uses only small quantities of reagents. It is therefore more environment-friendly than the conventional methods. The results showed quite a good analytical performance in terms of the repeatability, and recovery achieved in the tea matrices. QuEChERS combined with GC/MS/MS can be considered as a rapid and efficient monitoring technique for screening multiple pesticides in tea. The proposed monitoring technique provides the most effective approach to meet regulatory needs. Future work may include optimizing and validate the QuEChERS extraction method followed by LC/MS/MS simultaneous determination of polar, no-volatile and thermally unstable pesticide residues in tea. Finding and confirming nontargeted pesticides using GC/MS/MS and LC/quadrupole-time-of-flight (LC/Q-TOF/MS). The application of the method for measuring pesticides in tea samples (Oolong tea, black 11

tea, white tea and green tea) collected from different places in Taiwan will also be planned. In addition, there should be an investigation of the risk assessment of tea infusions.

Acknowledgment This research was funded by a grant from the Council of Agriculture, Taiwan (project: 100AS-6.2.1-TS-T1). Analysis by Zheng-Wai Lin, Chih Yu Lo, Ming Hua Tsai, Xu Fang Wang, Xu Jing Wang and Yu-Ju Huang of Tea Research and Extension Station.

References Anastassiades, M., Lehotay, S. J., Stajnbaher, D., & Schenck, F. J. (2003). Fast and easy multiresidue method employing acetonitrile extraction/partitioning and dispersive solid-phase extraction for the determination of pesticide residues in produce. Journal of AOAC International, 86, 412-431. Commission Decision 2002/657/EC of 12 August 2002 implementing Council Directive 96/23/EC concerning the performance of analytical methods and the interpretation of result" (Official Journal of the European Communities L221, 17.8.2002) . Accessed 10.02.16. Economou, A., Botitsi, H., Antoniou, S., & Tsipi, D. (2009). Determination of multi-class pesticides in wines by solid-phase extraction and liquid chromatography-tandem mass spectrometry. Journal of Chromatogr A, 1216, 5856---5867. Elham, J., Fatemeh, A., & Mansour, F. (2016). Evaluation of QuEChERS sample preparation and GC mass spectrometry method for the determination of 15 12

pesticide residues in tomatoes used in salad production plants. Iran Journal of Public Health, 45, 230---238. European Standard EN 15662:2008. (2008). Foods of plant origin-Determination of pesticide residues using GC-MS and/or LC-MS/MS following acetonitrile extraction/partitioning and clean-up by dispersive SPE (QuEChERS-method). < http:// www.chromnet.net/Taiwan/ QuEChERS_ Dispersive_SPE/QuEChERS_%e6%ad%90%e7%9b%9f%e6%96%b9%e6%b3 %95_EN156622008_E. pdf>. Accessed 10.02.16. Lehotay, S.J., & Eller, K.I. (1995). Development of a method of analysis for 46 pesticides in fruits and vegetables by supercritical fluid extraction and gas chromatography/ion trap mass spectrometry. Journal of AOAC International, 78, 821-830. Lin, Z.W., Wu, C. C., & Ho, C. J. (2008). Dissipation of four synthetic pyrethroids pesticides in tea plants expose to rain. Taiwan Tea Research Bulletin, 27, 63-72. Luke, M. A., & Doose, G. M. (1983). A modification of the Luke multiresidue procedure for low moisture, nonfatty products. Bulletin of Environmental Contamination & Toxicology, 30, 110-116. SANCO/10476/2003. (2004). Quality control procedures for pesticide residues analysis.


Sanco_2003_10476.pdf>. Accessed 10.02.16. SANCO/10232/2006. (2006). Quality control procedures for pesticide residue analysis. . Accessed 10.02.16. SANCO/2007/3131. (2007). Method validation and quality control procedures for pesticide residues analysis in food and feed. .

Accessed 10.02.16. 13

Shivani, J., Sood, C., Kuma, V., Ravindranath, S.D., & Shanker, A. (2001) Leaching of pesticides in tea brew. Journal of Agricultural and Food Chemistry, 49, 5479-83. Tekel, J., & Hatrik, S. (1996). Pesticide residue analyses in plant material by chromatographic methods: clean-up procedures and selective detectors. Journal of AOAC International A, 754, 397-410. Tesfa, B., Abera, G., & Negussie, M. (2015). Modified QuEChERS method for the determination of multiclass pesticide residues in fruit samples utilizing high-performance liquid chromatography. Food Analytical Methods, 8, 2020---2027. Wang, L., & Curtis, L.W. (2006). Recent advances in extraction of nutraceuticals from plants. Trends in Food Science & Technology, 17, 300---312. Wu, C. C. (2001). Study on the residual of carbamate insecticides in the fresh tea leaves in Taiwan. Taiwan Tea Research Bulletin, 20, 43-52. Wu, C. C. (2003). Studies on the residue of organophosphate insecticides in the fresh tea leaves. Taiwan Tea Research Bulletin, 22,101-112. Wu, C. C., Chu. C., Wang, Y.S., & Lur, H. S. (2007). Dissipation of carbofuran and carbaryl on Oolong tea during tea bushes, manufacturing and roasting processes. Journal of Environmental Science and Health, Part B, 42, 669-675. Wu, C. C., Chu. C., Wang, Y. S., & Lur, H. S. (2009).

Analysis of carbamate

pesticides residues in tea samples by high-performance liquid chromatography with fluorescence detector. Journal of Environmental Science and Health, Part B, 44, 58-68. Wu, C. C., Li, Z. W., Lin, Z. W. & Chu, M. W. (2010). LC/MS/MS analysis of carbamate pesticides residues in tea. Taiwan Tea Research Bulletin, 29,77-88. Wu, C. C., Yang, H. Y., Chuang, Y. H., Huang, Y. J., Lin, L. C., & Chen, I. Z. (2012). 14

Application of laboratory information management system in tea pesticide analysis laboratory. Journal of Environmental Science and Engineering B1, 12, 1311-1321.

Table 1 The optimized GC/MS/MS MRM acquisition parameters of the targeted pesticides.

Table 2 Linearity, calibration curves, limits of detection (LODs), and limits of quantification (LOQs) for the 89 pesticides in the GCMSMS under study. The limits of detection (LODs) and quantification (LOQs) in this procedure were defined as the concentrations of each of the pesticides in the tea samples (expressed as -1

(µgg L ) that gave signals of 3 and 10 times the noise, respectively.

Table 3 Recoveries of spiking at different concentrations of carbonated pesticides in the tea samples. a

Recovery (%) = 100% × (Level of pesticides in spiked sample level of pesticides in

blank sample) / Level of pesticides in spiked tea sample. b

Relative standard deviation (RSD).

Fig. 1. The QuEChERS extracted procedure and analyzed by GC/MS/MS. 15

Fig. 2. Chromatograms for: A: blank tea sample; B: tea sample spiked with 89 pesticides at 100 µg L−1.

16

Fig. 1. The QuEChERS extracted procedure and analyzed by GC/MS/MS.

A

B

Fig. 2. Chromatograms for: A: blank tea sample; B: tea sample spiked with 89 pesticides at 100 µg L−1.

17

Highlight ►QuEChERs with GC/MS/MS determination of pesticide residues in Oolong tea with high sensitivity. ► Optimization of GC/MS/MS, matrix-matched calibration curve, LODs and LOQs, were investigated. ► Confirm the accuracy of QuEChERs with GC/MS/MS method by the laboratory proficiency test.

18

1 2

Table 1 The optimized GC/MS/MS MRM acquisition parameters of the targeted pesticides. quantification Pesticide

3

qualification

Rention time

MRM

Collision

MRM

Collision

(RT)

transition

energy

transition

energy

(m/z)

(eV)

(m/z)

(eV)

Alachlor

17.02

160.05＞130.00

30

160.05＞131.10

10

Benfluralin

11.72

291.70＞206.30

15

291.70＞264.10

15

Bifenox

29.21

311.00＞279.30

10

311.00＞216.30

20

Bifenthrin

28.84

180.80＞165.10

20

180.80＞166.10

20

Bromophos methyl

20.08

331.00＞316.00

20

331.00＞286.00

20

Bromophos-ethyl

22.55

358.70＞303.00

15

358.70＞331.00

5

Bromopropylate

28.65

341.00＞183.00

20

341.00＞185.00

20

Bupirimate

24.80

273.00＞108.00

15

273.00＞193.00

5

Butachlor

23.22

175.80＞146.10

20

237.00＞160.00

5

Butralin

20.20

265.90＞190.20

10

265.90＞220.20

10

Carbophenothion

26.66

153.00＞96.90

10

157.00＞121.00

25

Chinomethionat

21.98

234.00＞206.00

10

206.00＞148.00

15

Chlorfenapyr

25.29

247.00＞227.00

15

247.00＞197.00

20

Chlorpyrifos

19.23

198.70>171.00

30

198.70>97.90

30

Chlorpyriphos-methyl

16.61

286.00＞93.00

20

286.00＞270.90

20

Chlozolinate

21.39

188.10＞147.10

15

330.80＞259.10

5

4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

24 25

Table 1 The optimized GC/MS/MS MRM acquisition parameters of the targeted pesticides. (continue) quantification Pesticide

qualification

Rention time

MRM

Collision

MRM

Collision

(RT)

transition

energy

transition

energy

(m/z)

(eV)

(m/z)

(eV)

Cyanofenphos

26.83

168.90＞77.00

30

168.90＞141.00

5

Cyfluthrin

32.43

163.00＞91.00

15

163.00＞127.00

5

Cyhalothrin

30.39

197.00＞161.00

10

181.00＞152.00

5

Cypermethrin

33.03

162.70＞91.00

25

180.70＞152.10

25

Deltamethrin

35.94

253.00>93.00

22

253.00>174.00

10

Diazinon

14.45

136.80＞84.00

10

136.80＞54.10

30

Dicofol

19.25

138.90>111.00

30

249.8>139.0

15

Dieldrin

23.88

263.00＞193.00

30

263.00＞191.00

30

Diniconazole

25.59

268.00＞232.00

15

270.00＞234.00

15

Dinitramine

14.84

305.00＞216.00

10

305.00＞244.00

15

Dioxabenzofos

11.47

215.80＞201.10

10

215.80＞138.10

10

Disulfoton

14.54

274.00＞88.00

5

186.00＞142.00

5

Ditalimfos

23.24

129.80＞102.10

25

129.80＞75.10

25

EPN

28.68

157.00＞77.10

25

157.00＞110.00

15

Ethion

21.98

230.70＞175.00

5

230.70＞203.10

5

Ethoprophos

10.76

157.80＞114.00

5

157.80＞96.90

5

Etrimfos

15.16

292.00＞181.00

5

292.00＞153.00

20

26 27

28 29 30 31

Table 1 The optimized GC/MS/MS MRM acquisition parameters of the targeted pesticides. (continue) quantification Pesticide

qualification

Rention time

MRM

Collision

MRM

Collision

(RT)

transition

energy

transition

energy

(m/z)

(eV)

(m/z)

(eV)

Fenazaquin

29.14

160.00＞145.20

5

145.00＞115.20

20

Fenitrothion

18.08

277.10＞109.00

20

277.00＞260.00

5

Fenpropathrin

29.00

181.00＞152.00

25

265.00＞210.00

15

Fenthion

19.12

278.00＞109.00

10

278.00＞125.00

15

Fenvalerate

34.60

167.00＞125.00

10

225.00＞119.00

15

Fipronil

21.90

367.00＞213.00

30

367.00＞228.00

30

Flucythrinate

33.35

199.00＞107.00

30

199.00＞157.00

5

Fluvalinate

34.88

250.00＞200.00

22

252.00＞200.00

18

Fonofos

13.89

246.00＞109.10

15

246.00＞81.10

30

Halfenprox

32.81

263.00＞169.00

25

263.00＞235.00

15

Haloxyfop-methyl

22.87

375.00＞91.00

30

288.00＞180.00

20

Heptachlor

16.78

272.00＞237.00

20

274.00＞239.00

20

Heptachlor Epoxide

20.72

352.90＞262.90

10

352.90＞281.90

15

32

Iprobenfos

15.35

204.00＞91.10

10

90.90＞39.10

25

Iprodione

28.46

313.60＞56.10

10

313.60＞245.10

10

33 34

Isazofos

15.02

118.80＞76.00

15

118.80＞84.10

15

35

Isofenphos

21.60

213.00＞121.05

15

255.00＞121.00

25

36 37

38 39 40 41

Table 1 The optimized GC/MS/MS MRM acquisition parameters of the targeted pesticides. (continue) quantification Pesticide

qualification

Rention time

MRM

Collision

MRM

Collision

(RT)

transition

energy

transition

energy

(m/z)

(eV)

(m/z)

(eV)

Kresoxim-methyl

24.89

206.00＞116.00

5

206.00＞131.00

10

Malathion

18.78

126.90＞99.00

15

126.90＞71.10

15

Methiocarb

18.09

168.00＞153.00

10

153.00＞109.00

10

Metolachlor

18.91

162.15＞133.10

15

162.15＞132.10

25

Metribuzin

16.30

198.05＞82.10

20

198.05＞89.00

15

Mirex

29.85

271.60＞237.00

5

271.60＞234.90

20

Oxadiazon

24.43

174.90＞112.00

15

301.90＞175.00

13

p,p'-DDE

24.05

246.00＞176.10

30

248.00＞176.00

30

Parathion

19.28

291.00＞109.00

10

291.10＞81.00

40

42

Parathion-methyl

16.61

263.00＞109.10

15

263.00＞79.10

30

Penconazole

21.05

248.00>157.00

25

248.00>192.00

15

43 44

Pendimethalin

21.00

252.10＞162.10

10

252.10＞161.20

20

Permethrin

31.53

183.00＞153.00

20

183.00＞168.00

20

Phenthoate

21.71

274.00＞121.00

10

274.00＞125.00

20

Phorate

11.95

121.00＞65.00

10

260.00＞75.20

5

47 48

Pirimiphos-ethyl

20.65

167.80＞100.10

20

167.80＞69.20

20

49

Pirimiphos-methyl

18.29

290.10＞125.00

25

305.00＞180.00

5

50

45 46

51 52 53 54 55

Table 1 The optimized GC/MS/MS MRM acquisition parameters of the targeted pesticides. (continue) quantification Pesticide

qualification

Rention time

MRM

Collision

MRM

Collision

(RT)

transition

energy

transition

energy

(m/z)

(eV)

(m/z)

(eV)

Pretilachlor

24.13

161.80＞132.10

15

161.80＞147.20

15

Procymidone

21.99

283.00＞96.00

10

283.00＞255.00

10

Profenofos

23.94

208.00＞63.10

35

337.00＞267.00

10

Propaphos

22.69

219.70＞125.00

30

219.70＞140.20

5

Propoxur

10.36

110.00＞63.00

30

110.00＞64.00

20

56

Prothiofos

23.78

267.00＞239.00

5

309.00＞239.00

15

Pyrazophos

30.70

221.00＞193.00

10

232.00＞204.00

10

57 58

Pyridaben

31.56

147.00＞117.00

20

147.00＞132.00

10

Pyriproxyfen

29.89

136.00＞78.00

25

136.00＞96.00

15

Quinalphos

21.67

146.00＞118.00

10

157.00＞129.00

15

Quizalofop-ethyl

32.98

372.00＞299.00

5

299.00＞255.00

15

Tetradifon

29.42

354.00＞159.00

10

356.00＞159.00

10

Tetramethrin

28.75

164.00＞77.00

25

164.00＞107.00

25

Triazophos

26.48

161.00＞106.00

10

161.00＞134.00

5

Triflumizole

22.36

206.00＞179.20

10

287.00＞218.00

15

Trifluralin

11.64

305.90＞43.20

15

305.90＞264.10

10

Vinclozolin

16.65

212.00＞145.00

15

212.00＞172.00

25

59 60 61 62 63 64 65 66 67 68 69

70 71 72 73 74 75 76 77 78

79 80

Table 1 The optimized GC/MS/MS MRM acquisition parameters of the targeted pesticides. (continue) quantification Pesticide

92 93 94 95 96 97 98 99 100 101 102

qualification

Rention time

MRM

Collision

MRM

(RT)

transition

energy

transition

(m/z)

(eV)

(m/z)

α-BHC

12.10

182.70＞146.70

15

182.70＞145.20

α-chlordane (cis)

22.84

272.00＞237.00

20

372.70＞266.10

α-Endosulfan

22.63

238.80＞204.00

15

195.00＞159.00

β-chlordane (trans)

22.05

372.70＞266.10

25

372.70＞264.10

β-Endosulfan

25.19

119.90＞102.30

5

119.90＞85.20

81 82 Collision 83 energy 84 (eV) 85 15 86 25 87 5 88 25 89 25 90 91

103 104

Table 2 Linearity, calibration curves, limits of detection (LODs), and limits of quantification (LOQs) for the 89 pesticides in the GC/MS/MS under study. Pesticide

Linear range -1

Alachlor

of

linearity

LOD

LOQ

Intercept

(µg L )

(µg L-1)

2.067× 101

- 11.240

2.50

10

1

- 67.402

1.00

10

(µg L )

r

Slope

1 - 250

0.9988

-1

Benfluralin

1 - 250

0.9969

1.810× 10

Bifenox

1 - 250

0.9847

6.336× 101

53.758

1.00

10

Bifenthrin

1 - 250

0.9991

2.295× 102

197.071

1.00

10

0.9993

4.193× 10

1

- 12.539

1.00

10

1

- 28.679

1.00

10

Bromophos methyl

1 - 250

Bromophos-ethyl

1 - 250

0.9992

4.258× 10

Bromopropylate

1 - 250

0.9991

6.789× 101

3.894

1.00

10

Bupirimate

1 - 250

0.9994

2.461× 101

- 18.688

1.00

10

0.9998

1.502× 10

1

14.858

1.00

10

1

- 81.548

1.00

10

Butachlor

1 - 250

Butralin

1 - 250

0.9955

1.875× 10

Carbophenothion

1 - 250

0.9987

4.610× 101

- 28.815

5.00

10

Chinomethionat

1 - 250

0.9988

8.972× 101

- 129.562

1.00

10

0.9992

2.782× 10

1

12.088

2.50

10

1.032× 10

1

90.515

1.00

10

1

- 29.181

1.00

10

Chlorfenapyr Chlorpyrifos

1 - 250 1 - 250

0.9995

Chlorpyriphos-methyl

1 - 250

0.9995

3.585× 10

Chlozolinate

1 - 250

0.9987

1.573× 101

- 17.670

1.00

10

Cyanofenphos

1 - 250

0.9993

5.192× 101

- 22.042

1.00

10

0.9989

1

20.900

25.00

50

Cyfluthrin

105

Parameters 2

1 - 250

6.111× 10

106 107 108

Table 2 Linearity, calibration curves, limits of detection (LODs), and limits of quantification (LOQs) for the 89 pesticides in the GC/MS/MS under study. (continue) Pesticide

Linear range -1

Cyhalothrin Cypermethrin

Parameters 2

linearity

LOD

LOQ

Intercept

(µg L )

(µg L-1)

1.787× 101

- 34.421

1.00

10

1.624× 10

2

66.712

1.00

10

1

- 80.828

1.00

10

(µg L )

r

Slope

1 - 250

0.9983 0.9979

1 - 250

of

-1

Deltamethrin

1 - 250

0.9967

3.132× 10

Diazinon

1 - 250

0.9993

3.690× 101

- 41.066

1.00

10

Dicofol

1 - 250

0.9994

3.066× 101

- 8.515

1.00

10

0.9995

7.589× 10

1

1.747

1.00

10

1

- 35.041

10.00

20

Dieldrin

1 - 250

Diniconazole

1 - 250

0.9994

3.687× 10

Dinitramine

1 - 250

0.9947

1.833× 101

- 21.468

1.00

10

Dioxabenzofos

1 - 250

0.9991

5.669× 101

- 44.559

2.50

10

Disulfoton

1 - 250

0.9974

1.045× 101

- 28.307

1.00

10

0.9995

5.673× 10

1

- 12.512

2.50

10

1

- 92.002

1.00

10

Ditalimfos

1 - 250

EPN

1 - 250

0.9978

4.395× 10

Ethion

1 - 250

0.9992

4.189× 101

- 24.249

1.00

10

Ethoprophos

1 - 250

0.9992

3.900× 101

- 30.891

1.00

10

0.9992

3.884× 10

1

- 50.426

1.00

10

2

- 90.507

1.00

10

- 62.374

1.00

10

Etrimfos

1 - 250

Fenazaquin

1 - 250

0.9991

1.552× 10

Fenitrothion

1 - 250

0.9970

2.394× 101

Fenpropathrin

1 - 250

0.9991

3.311× 101

20.992

1.00

10

Fenthion

1 - 250

0.9995

4.088× 101

- 5.009

1.00

10

109 110 111 112 113

Table 2 Linearity, calibration curves, limits of detection (LODs), and limits of quantification (LOQs) for the 89 pesticides in GC/MS/MS under study.(continue) Pesticide

Linear range -1

Parameters 2

1.00

10

3.344× 101

- 39.888

5.00

10

7.909× 10

1

- 155.402

1.00

10

2.482× 10

1

- 93.885

2.50

10

1

- 60.808

1.00

10

Fenvalerate

1 - 250

0.9988

1.798× 102

Fipronil

1 - 250

0.9993 0.9988

1 - 250

0.9970

LOQ

- 327.376

Slope

Fluvalinate

LOD

(µg L-1)

r

1 - 250

linearity

(µg L )

(µg L )

Flucythrinate

of

Intercept

-1

Fonofos

1 - 250

0.9993

6.261× 10

Halfenprox

1 - 250

0.9981

1.788× 101

- 44.842

1.00

10

Haloxyfop-methyl

1 - 250

0.9988

1.361× 101

- 19.564

1.00

10

0.9984

3.338× 10

1

- 54.099

1.00

10

1

- 22.763

2.50

10

Heptachlor

1 - 250

Heptachlor Epoxide

1 - 250

0.9992

1.506× 10

Iprobenfos

1 - 250

0.9992

1.246× 102

- 188.196

5.00

10

Iprodione

1 - 250

0.9979

8.718× 101

- 25.826

1.00

10

0.9991

1.374× 10

1

- 11.686

1.00

10

9.433× 10

1

- 87.245

1.00

10

Isazofos Isofenphos

1 - 250 1 - 250

0.9991

Kresoxim-methyl

1 - 250

0.9991

2.754× 101

- 30.209

1.00

10

Malathion

1 - 250

0.9996

3.355× 101

- 7.801

1.00

10

0.9984

6.447× 10

1

- 107.577

1.00

10

2

- 69.252

1.00

10

Methiocarb

1 - 250

Metolachlor

1 - 250

0.9991

1.079× 10

Metribuzin

1 - 250

0.9991

3.656× 101

- 52.230

1.00

10

Mirex

1 - 250

0.9992

4.326× 101

- 60.324

1.00

10

114 115 116 117 118

Table 2 Linearity, calibration curves, limits of detection (LODs), and limits of quantification (LOQs) for the 89 pesticides in the GC/MS/MS under study. (continue) Pesticide

Linear range -1

Parameters

of linearity

LOD

LOQ

(µg L )

r

Slope

Intercept

(µg L )

(µg L-1)

Oxadiazon

1 - 250

0.9994

8.834× 101

- 25.943

1.00

10

p,p'-DDE

1 - 250

0.9994

8.146× 101

- 58.117

1.00

10

Parathion

1 - 250

0.9958

3.104× 101

- 129.426

1.00

10

0.9965

4.896× 10

1

- 156.463

2.50

10

1

- 61.826

1.00

10

Parathion-methyl

1 - 250

2

-1

Penconazole

1 - 250

0.9990

5.159× 10

Pendimethalin

1 - 250

0.9955

2.450× 101

- 94.184

1.00

10

Permethrin

1 - 250

0.9978

3.031× 101

7.303

2.50

10

0.9991

4.792× 10

1

- 45.491

1.00

10

5.649× 10

1

- 10.149

1.00

10

Phenthoate Phorate

1 - 250 1 - 250

0.9986

Pirimiphos-ethyl

1 - 250

0.9996

7.996× 101

- 10.272

2.50

10

Pirimiphos-methyl

1 - 250

0.9993

2.535× 101

- 26.639

1.00

10

0.9996

1

8.432

1.00

10

1

16.199

1.00

10

Pretilachlor

1 - 250

4.518× 10

Procymidone

1 - 250

0.9994

4.311× 10

Profenofos

1 - 250

0.9982

1.234× 101

- 17.928

1.00

10

Propaphos

1 - 250

0.9992

5.775× 101

- 51.683

1.00

10

0.9988

1.368× 10

2

- 19.891

1.00

10

1

- 23.570

1.00

10

Propoxur

1 - 250

Prothiofos

1 - 250

0.9990

4.264× 10

Pyrazophos

1 - 250

0.9994

8.016× 101

- 23.818

1.00

10

Pyridaben

1 - 250

0.9993

1.319× 102

- 69.734

1.00

10

119 120 121 122 123

Table 2 Linearity, calibration curves, limits of detection (LODs), and limits of quantification (LOQs) for the 89 pesticides in the GC/MS/MS under study. (continue) Pesticide

Linear range -1

Parameters

of linearity

28.629

1.00

10

1.251× 102

- 153.969

2.50

10

0.9993

3.766× 101

- 37.413

1.00

10

0.9998

1.149× 10

1

- 4.720

1.00

10

1.009× 10

2

40.456

2.50

10

r

Slope

Pyriproxyfen

1 - 250

0.9993

6.638× 101

Quinalphos

1 - 250

0.9991

Quizalofop-ethyl

1 - 250

Tetramethrin

1 - 250 1 - 250

LOQ (µg L-1)

(µg L )

Tetradifon

LOD (µg L )

2

0.9988

Intercept

-1

Triazophos

1 - 250

0.9995

3.069× 101

19.696

1.00

10

Triflumizole

1 - 250

0.9982

2.345× 101

- 18.026

2.50

10

0.9973

1.875× 10

1

- 57.267

1.00

10

1

- 5.501

2.50

10

Trifluralin Vinclozolin

1 - 250

0.9997

7.502× 10

α-BHC

1 - 250

0.9993

2.125× 101

- 17.007

1.00

10

α-chlordane (cis)

1 - 250

0.9993

1.021× 101

- 7.651

1.00

10

0.9994

6.540× 10

1

- 13.312

2.50

10

1

- 17.034

1.00

10

- 4.684

1.00

20

α-Endosulfan

124 125 126

1 - 250

1 - 250

β-chlordane (trans)

1 - 250

0.9991

1.358× 10

β-Endosulfan

1 - 250

0.9987

3.471× 101

The limits of detection (LODs) and quantification (LOQs) in this procedure were defined as the concentrations of each of the pesticides in the tea samples (expressed as (µg L-1) that gave signals of 3 and 10 times the noise, respectively.

127 128

Table 3 Recoveries of spiking at different concentrations of carbonated pesticides in the tea samples. Spiked level (µg L-1)

Pesticide 50

100

Alachlor

76.1 (16.8)

77.0 (6.5)

Benfluralin

68.3 (17.1)

63.6(0.6)

111.3 (26.6)

129.4 (8.0)

Bifenthrin

78.2 (7.4)

77.9(1.1)

Bromophos methyl

67.2 (16.1)

66.7 (3.6)

Bromophos-ethyl

75.6 (12.5)

77.6(0.5)

Bromopropylate

81.6 (13.9)

81.8(3.4)

Bupirimate

73.7 (13.9)

75.1 (8.1)

Butachlor

84.4 (16.3)

83.4 (5.1)

Butralin

74.9 (7.6)

71.3 (5.0)

Carbophenothion

78.7 (13.2)

79.5 (2.4)

Chinomethionat

65.7 (16.7)

64.7 (4.6)

Chlorfenapyr

86.8 (15.4)

85.7 (7.8)

Chlorpyrifos

76.4 (21.3)

79.9 (6.0)

Chlorpyriphos-methyl

72.7 (18.5)

71.6 (5.0)

Chlozolinate

80.6 (13.9)

81.8 (3.0)

Cyanofenphos

80.0 (15.1)

81.4 (5.2)

Cyfluthrin

134.5 (5.8)

82.6 (5.5)

Bifenox

129 130 131

Table 3 Recoveries of spiking at different concentrations of carbonated pesticides in the tea samples. (continue) Spiked level (µg L-1)

Pesticide 50

100

Cyhalothrin

78.8 (11.4)

79.6 (4.7)

Cypermethrin

72.8 (7.2)

74.1 (3.7)

Deltamethrin

70.1 (7.4)

66.2 (8.4)

Diazinon

64.7 (26.9)

60.6 (3.7)

Dicofol

71.7 (8.6)

75.0 (1.9)

Dieldrin

75.8 (14.8)

78.8 (3.9)

Diniconazole

66.9 (20.4)

66.8 (9.2)

Dinitramine

95.8 (8.0)

82.6 (8.6)

Dioxabenzofos

69.4 (19.9)

66.4 (6.2)

Disulfoton

65.7 (15.0)

65.1 (3.2)

Ditalimfos

73.09 (13.2)

74.6 (6.1)

EPN

76.9 (10.6)

73.6 (6.5)

Ethion

83.1 (16.5)

82.8 (4.2)

Ethoprophos

72.0 (21.3)

71.9 (6.5)

Etrimfos

79.8 (15.5)

78.5 (3.9)

Fenazaquin

66.6 (21.0)

73.9 (8.0)

Fenitrothion

67.8 (13.3)

64.3 (5.1)

Fenpropathrin

85.7 (14.8)

83.4 (4.6)

Fenthion

75.1 (15.8)

77.7 (4.6)

132 133 134 135 136

Table 3 Recoveries of spiking at different concentrations of carbonated pesticides in the tea samples. (continue) Spiked level (µg L-1)

Pesticide 50

100

Fenvalerate

77.4 (11.7)

75.7 (3.3)

Fipronil

84.4 (15.6)

79.3 (3.6)

Flucythrinate

78.6 (13.1)

80.1 (4.5)

Fluvalinate

77.6 (12.9)

75.0 (4.0)

Fonofos

75.0 (18.0)

74.3 (3.1)

Halfenprox

71.4 (6.6)

70.0 (2.1)

Haloxyfop-methyl

84.6 (18.9)

87.4 (2.7)

Heptachlor

57.8 (20.0)

58.2 (2.5)

Heptachlor Epoxide

78.8 (13.9)

77.4 (3.6)

Iprobenfos

74.6 (16.1)

74.2 (8.7)

Iprodione

69.6 (12.7)

67.5 (14.8)

Isazofos

82.5 (17.3)

81.3 (7.6)

Isofenphos

85.5 (14.8)

85.6 (4.4)

Kresoxim-methyl

82.6 (15.9)

81.8 (7.7)

Malathion

78.0 (17.9)

77.3 (6.1)

Methiocarb

63.6 (15.3)

55.4 (9.1)

Metolachlor

78.5 (17.4)

79.4 (7.9)

Metribuzin

64.2 (11.2)

62.5 (7.5)

Mirex

57.8 (8.0)

53.7 (8.0)

137 138 139 140 141

Table 3 Recoveries of spiking at different concentrations of carbonated pesticides in the tea samples. (continue) Spiked level (µg L-1)

Pesticide 50

100

Oxadiazon

86.2 (16.3)

87.7 (5.2)

p,p'-DDE

71.5 (10.6)

70.6 (3.5)

Parathion

77.3 (12.2)

70.8 (6.6)

Parathion-methyl

63.5 (13.5)

57.7 (7.2)

Penconazole

64.9 (17.4)

63.4 (10.0)

Pendimethalin

74.1 (12.9)

71.3 (2.7)

Permethrin

76.3 (8.5)

75.8 (1.6)

Phenthoate

80.3 (14.1)

79.7 (6.4)

Phorate

68.8 (21.2)

65.4 (2.7)

Pirimiphos-ethyl

82.4 (8.8)

84.5 (4.5)

Pirimiphos-methyl

80.9 (17.1)

82.8 (6.5)

Pretilachlor

77.7 (13.4)

81.8 (7.4)

Procymidone

81.6 (17.3)

83.0 (5.7)

Profenofos

72.0 (15.6)

69.0 (8.6)

Propaphos

70.2 (17.6)

70.0 (10.1)

Propoxur

60.5 (14.0)

57.4 (6.7)

Prothiofos

74.7 (12.5)

74.9 (1.4)

Pyrazophos

69.6 (15.2)

71.9 (7.8)

Pyridaben

74.8 (13.6)

75.9 (5.2)

142 143 144 145 146

Table 3 Recoveries of spiking at different concentrations of carbonated pesticides in the tea samples. (continue) Spiked level (µg L-1)

Pesticide 50

100

Pyriproxyfen

80.4 (13.9)

80.9 (2.3)

Quinalphos

79.6 (16.8)

77.1 (5.3)

Quizalofop-ethyl

75.3 (16.9)

77.2 (7.2)

Tetradifon

77.2 (13.5)

77.6 (5.6)

Tetramethrin

78.0 (16.2)

79.9 (6.3)

Triazophos

67.4 (17.1)

67.6 (7.2)

Triflumizole

68.2 (20.2)

67.1 (8.9)

Trifluralin

68.5 (16.5)

64.5 (1.3)

Vinclozolin

81.7 (16.6)

84.0 (5.8)

α-BHC

69.6 (20.5)

67.7 (3.6)

α-chlordane (cis)

72.1 (13.1)

71.5 (0.2)

α-Endosulfan

76.9 (10.2)

79.9 (5.3)

β-chlordane (trans)

73.0 (11.0)

71.1 (2.8)

β-Endosulfan

68.8 (14.2)

74.9 (9.0)

147 148

a

Recovery (%) = 100% × (Level of pesticides in spiked sample level of pesticides in blank sample) / Level of pesticides in spiked tea sample.

149

b

Relative standard deviation (RSD).