Aerosol dilution as a simple strategy for analysis of complex samples by ICP-MS

Author’s Accepted Manuscript Aerosol dilution as a simple strategy for analysis of complex samples by ICP-MS Ariane I. Barros, Fernanda C. Pinheiro, Clarice D.B. Amaral, Rodolfo Lorençatto, Joaquim A. Nóbrega www.elsevier.com/locate/talanta

PII: DOI: Reference:

S0039-9140(17)31063-9 https://doi.org/10.1016/j.talanta.2017.10.024 TAL18022

To appear in: Talanta Received date: 1 September 2017 Revised date: 13 October 2017 Accepted date: 15 October 2017 Cite this article as: Ariane I. Barros, Fernanda C. Pinheiro, Clarice D.B. Amaral, Rodolfo Lorençatto and Joaquim A. Nóbrega, Aerosol dilution as a simple strategy for analysis of complex samples by ICP-MS, Talanta, https://doi.org/10.1016/j.talanta.2017.10.024 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. 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.

Aerosol dilution as a simple strategy for analysis of complex samples by ICP-MS Ariane I. Barros1*, Fernanda C. Pinheiro1, Clarice D. B. Amaral2, Rodolfo Lorençatto3, Joaquim A. Nóbrega1

1

Group for Applied Instrumental Analysis, Department of Chemistry, Federal University of São Carlos, P.O. Box 676, São Carlos, SP, 13560-270, Brazil

2

Department of Chemistry, Federal University of Paraná, Curitiba, PR, Brazil. 3

*

Agilent Technologies, São Paulo, SP, Brazil

Corresponding author: [email protected]

ABSTRACT This study investigated the capability of High Matrix Introduction (HMI) strategy for analysis of dialysis solution and urine samples using inductively coupled plasma mass spectrometry. The use of HMI enables the direct introduction of urine samples and dialysis solutions 2-fold diluted with 0.14 mol L-1 HNO3. Bismuth, Ge, Ir, Li, Pt, Rh, Sc and Tl were evaluated as internal standards for Al, Ag, As, Be, Cd, Cr, Pb, Sb, Se, Tl, and Hg determination in dialysis solution and As, Cd, Hg and Pb determination in urine samples. Helium collision cell mode (4.5 mL min-1) was efficient to overcome polyatomic interferences in As, Se and Cr determinations. Mercury memory effects were evaluated by washing with 0.12 mol L-1 HCl or an alkaline diluent solution prepared with n-butanol, NH4OH, EDTA, and Triton X-100. This later solution was efficient for avoiding Hg memory effects in 6 h of analysis. Linear calibration curves were obtained for all analytes and detection limits were lower than maximum amounts allowed by Brazilian legislations. Recoveries for all analytes in dialysis solutions and urine samples ranged from 82 to 125% and relative standard deviations 1

for all elements and samples were lower than 7%. Analysis of control internal urine samples was in agreement with certified values at 95% confidence level (t-test; p < 0.05).

Keywords: ICP-MS, HMI, Saline matrices, Internal standard

1. Introduction

The analysis of complex matrices by inductively coupled plasma mass spectrometry (ICP-MS) has been challenging in elemental analysis especially for determination at trace and ultra-trace levels. Despite superb sensitivities for most elements, ICP-MS is severely affected by matrix interferences. Solutions for peritoneal dialysis and human urine are good examples of challenging samples, both with high solids content, high salts concentration and with an important appeal for elemental impurities monitoring [1-3]. Peritoneal dialysis fluids are solutions that may be produced by dilution devices incorporated in the dialysis machine by mixing pre-treated water with powdered salts and concentrated electrolytic solutions. Patients of peritoneal dialysis are daily exposed to dialysis solution, therefore to know and to monitor the chemical and microbiological purity of dialysis solution is extremely important, since this fluid comes into direct contact with patient bloodstream [1]. The Brazilian Resolution RDC no. 11

2

presents requirements of good operating practices and water quality standard for dialysis, presenting strict limits for As, Cd, Hg, Pb and other elements [2]. Urine is a sample with variable composition representing the excretory endproducts of endocrine and metabolic processes [3], usually containing high levels of urea, sodium, potassium, uric acid, bicarbonate and chloride [4]. The Brazilian Regulatory Standard of Medical Occupational Health Control Program – NR7, recommends maximum values for As, Cd, Hg and Pb in this biological indicator in which it is assumed that most occupationally exposed persons are not at risk of health [5]. The Centers for Disease Control and Prevention (CDC) Environmental Health Laboratory at the National Center for Environmental Health (NCEH) adopt ICP-MS for elemental analysis in blood and urine of humans, once the fast analysis, sensitive measurements and multielemental capabilities enable high sample throughput for trace and ultra-trace levels [6,7]. The investigation of essential and potential toxic elements in urine by ICP-MS has been explored, usually the urine sample is diluted of 5-20 fold, with nitric or hydrochloric acid and/or surfactant [7-10]. Applications for elemental analysis of dialysis solutions are even less frequent and we did not find a recent paper using ICPMS. Sample dilution is often required in analyses by ICP-MS to keep the total dissolved solids (TDS) contents below 0.1 % m/v [11]. To overcome these limitations, High Matrix Introduction (HMI) technology uses auto-optimization of aerosol dilution to further improve matrix tolerance, reducing both aerosol density and water vapor loading in the plasma. Moreover, eliminate possible contaminations associated with manual dilution, save time and reduces waste volume compared with liquid dilution.

3

The sample aerosol is mixed with a specific flow of argon before entering the torch, i.e. between the spray chamber and the torch, thus reducing the density of the sample aerosol before it enters the plasma. The aerosol entering the plasma contains less solvent, avoiding a pronounced decrease of plasma energy and, consequently, leading to lower oxides formation [12-16]. Wilbur and Jones (2010) demonstrated the benefits of HMI system in compliant analysis of high matrix certified reference materials, such as river sediment and soil samples, for the determination of 26 elements [12]. In other study, sample dilution and internal standardization in aqueous samples was investigated using fast protein liquid chromatography (FPLC) coupled to ICP-MS with HMI system. The use of HMI reduced the sample aerosol transport and enabled direct determination of Cr species in presence of up to 4% m/v NaCl [13]. The capability of ICP-MS equipped with the HMI system for accurate analysis of lanthanides in environmental samples was investigated by Celo et al. (2011). The amounts of oxide and hydroxide molecular species formed in the plasma were 5-fold reduced and hydroxide formation was less than 0.02% [14]. Hein et al. (2017) developed a method for highly saline samples determination by ICP-MS coupled with ultra-high matrix introduction system (UHMI). It was suitable for analytes determination such as Eu and U in samples with NaCl concentrations up to 5 mol/L NaCl [15]. In addition to the drawbacks associated with traditional dilution strategy, such as sample contamination due to higher manipulation and higher generation of chemical residues, ICP-MS determination is susceptible to spectral and non-spectral interferences due to differences in the viscosity of the matrix, which may affect the nebulization process, and also due to spatial charge effects, which occur by electrostatic

4

interaction among ions affecting their trajectories, being this effect dependent on the isotope mass. To avoid transport effects, internal standardization has been used in routine analysis by ICP-MS, once it is a simple and fast strategy when compared to isotopic dilution and the standard additions method [17]. The difficulty of applying internal standardization in ICP-MS analysis is the choice of the internal standard itself (IS). The IS must be high purity, must not cause isobaric interferences to the analyte and should present mass and ionization energy similar to that of analyte [18,19]. In order to eliminate spectral interferences, collision cell technology (CCT) features a cell introduced before the mass spectrometer. The cell can be filled with an inert gas, such as He, that collides preferentially with interfering ions, generally a polyatomic specie, thus with larger diameter than the analyte. The species/ions with low energies are rejected by kinetic energy discrimination (KED), eliminating polyatomic interferences in a simple and versatile mode. Collision CT provides effective correction of polyatomic interferences, eliminating the need for reactive cell gases in routine analysis [11,20]. In this work, it was evaluated the performance of HMI and internal standardization for determination of Al, Ag, As, Be, Cd, Cr, Hg, Pb, Sb, Se and Tl in dialysis solutions and As, Cd, Hg and Pb in urine samples, meeting the current Brazilian legislations [2,5]. Effect of dilution gas flow rate and several ISs were studied in order to improve accuracy and precision of the analytical procedure. 2. Material and methods 2.1 Instrumentation Experiments were performed using an Agilent 7800 Quadrupole ICP-MS (Agilent Technologies, Tokyo, JHS, Japan) operated in two acquisition modes: (1) No gas-HMI and (2) He-HMI. No gas mode means not using the collision cell, and He 5

mode means when the collision cell is pressurized with pure He (99.999 %, White Martins-Praxair, Sertãozinho, SP, Brazil). HMI mode means the mode that the aerosol was diluted with Ar in the optimized dilution gas flow rate for HMI of 0.60 L/min and carrier gas flow rate of 0.42 L/min, thus 1.02 L/min of total flow rate. Argon (99.999 %, White Martins-Praxair) was used in all measurements. Plasma operating conditions are described in Table 1. 2.2 Reagents, standard solutions and samples Experiments were performed using HNO3 (Synth, Diadema, SP, Brazil) purified in a sub-boiling distillation apparatus DistillacidTM BSB-939-IR (Berghof, Eningen, Germany) and ultrapure water, resistivity > 18.2 MΩ cm, (Milli-Q®, Millipore, Bedford, MA, USA). Standard solutions used for ICP-MS calibration and for addition and recovery experiments were prepared by dilution of 1000 mg L-1 of Al, Ag, As, Be, Cd, Cr, Hg, Pb, Sb, Se and Tl (Qhemis, São Paulo, SP, Brazil) in 0.14 mol/L HNO3 medium, as well as the ISs evaluated: Bi, Ge, Ir, Li, Pt, Rh, Sc and Tl. The concentrations of the solutions used for obtaining analytical calibration curves were 0, 0.05, 0.1, 0.5, 1, 5, 10, 20, and 50 µg L-1 in 0.14 mol L-1 HNO3 medium for all elements. Addition and recovery experiments were performed at three addition levels (2, 5 and 10 µg L-1). Internal standards were added at 5 µg L-1 to the analytical calibration solutions, analytical blanks and samples. Two washing solutions were evaluated for cleaning the introduction system after measuring the analytical solutions and after every three readings: 0.12 mol L-1 HCl solution and an alkaline solution prepared by mixing 4% v/v n-butanol (Sigma-Aldrich, St. Louis, MO, USA), 1% w/v ammonium hydroxide (Sigma-Aldrich), 0.1% m/v ethylenediaminetetraacetic acid (EDTA, Sigma-Aldrich), and 0.05% v/v Triton X-100 (Sigma-Aldrich) for avoiding

6

memory effects affecting Hg determinations. After each cleaning step, a solution 0.14 mol L-1 HNO3 was aspirated. The samples analyzed were dialysis solutions at 1.25, 2.35 and 4.25 % m/v glucose and human urine samples 2-fold diluted. Dialysis solutions were purchased locally in the city of São Carlos (São Paulo, Brazil). Human urine samples used in this study were provided by healthy volunteers. The dissolved solids contents of these solutions are presented in Table S1 (Supplementary Information). An internal control used in occupational medicine monitoring - Metal in Urine, (National Program for Quality Control, code MEDT) was used to check the accuracy of the developed analytical procedure. For this same purpose, addition and recovery experiments were applied for the elements investigated in dialysis solution samples, since there is no certified reference material for this type of sample. 2.3 Optimization of the procedure

In order to optimize the HMI flow rate, acquisition mode (No gas or He) and aerosol dilution conditions, dialysis solution with 4.25 % m/v glucose was analyzed 2 and 5fold diluted with HNO3, varying the dilution gas flow rate for HMI from 0.50 to 0.70 L min-1, also with the variation of the nebulization gas flow rate from 0.52 to 0.32 L min-1, with increments of 0.10 L min-1, thus, the summation of both was kept at 1.02 L min-1.

7

The best working conditions were established according to recoveries of addition and recovery experiments for each condition. After optimization, isotope and acquisition mode were kept constant for each analyte. To evaluate the best cleaning solution for avoiding Hg memory effect, a stability study was performed using dialysis solutions and urine 2-fold diluted with 0.14 mol L-1 HNO3 both spiked with 5 µg L-1 Hg and analytical signals were continuously monitored for 10 h.

3. Results and discussion

3.1 Optimization of HMI system

Direct analysis of samples with high contents of dissolved solids (> 0.2 % m/v), such as dialysis solutions and urine, can cause oxide deposition at the interfaces of the cones and ionic lenses, and also intensify space charge effects. Thus, for ICP-MS determinations is essential to dilute the samples as much as possible as well as to stay above LOD [11]. However, there are some drawbacks associated with the conventional dilution of the samples, such as introduction of contaminants and generation of higher volumes of chemical residues. The HMI system allows the introduction of samples with TDS around 2% m/v. The greatest benefit of this system is the minimization of matrix suppression, resulting in a hotter plasma with sufficient energy to ionize the analytes and with lower formation of oxides. For dialysis solutions (Fig. S1) and urine sample (Fig. S2), good recoveries were obtained for Cd in all conditions evaluated, thus dilution gas flow rate of 0.60 L min-1 and 2-fold dilution factor were chosen. The same behavior was observed for all

8

analytes. It is important to highlight that analytical calibration solutions were not matrix-matched with samples composition. The polyatomic interferences, determination of

112

Cd and

208

40

Ca216O2 and

192

Pt16O+, can affect the

Pb, respectively. In Fig. S3 is presented the signal

intensities for Cd and Pb at different concentrations of Ca and Pt in the acquisition modes no gas-HMI and He-HMI. The same profile was observed with and without He mode collision cell, then the collision cell was not needed for Cd and Pb determination and Pt can be evaluated as IS. The use of HMI decreases the oxides formation and avoid several interferences [12], however, it is still necessary to use strategies for correcting for potential polyatomic interferences, such as 75

40

Ar35Cl+,

36

Ar38ArH+ and

23

Na12C40Ar+ affecting

As+, 38Ar40Ar+, 39Ar2+, 38Ar40Ca+ affecting 78Se+ and 40Ar12C+ affecting 52Cr+. Helium

mode collision cell (4.5 mL min-1) was efficient for correcting for polyatomic interferences as reported by Novotnik et al. [13].

3.2 Effect of washing solution on Hg memory effect

Determination of Hg by ICP-MS usually requires either addition of chloride [21], gold chloride [22], dichromate [23], EDTA [24], 2-mercaptoethanol (2-ME) [25] or alkaline solution [26] to the samples or the use of these chemicals as washing solution for avoiding memory effects. Amaral and co-workers adopted cleaning with HCl for avoiding memory effects in Hg determination in drinking water by ICP-MS [21]. Choe and Gajek proposed a solution prepared with 4 % v/v n-butanol, 1 % m/v ammonium hydroxide, 0.1 % m/v ethylenediaminetetraacetic acid (H4EDTA), and 0.05

9

% v/v Triton X-100 as dilution and cleaning solution for Hg determination in urine samples [26]. Both solutions, i.e. HCl (0.12 mol L-1) and alkaline mixture [26], were tested here considering the stability of Hg signals. After 97 min of measurements it was observed an increase in Hg signals when using HCl solution for washing of dialysis solutions (Fig. 3a). Due to this significative increase, Hg determination in time >97 min was aborted. When this same experiment was carried out using alkaline mixed solution, Hg analytical signals were constant for dialysis solution (Fig. 1a) until 350 min and urine sample (Fig. 1b) until 500 min, showing that the alkaline solution was more efficient for avoiding Hg memory effects than HCl solution. Further experiments were performed using alkaline solution for washing between samples when determining Hg.

3.3 Methods accuracy and evaluation of internal standardization

The accuracy and precision of the analytical procedure were evaluated by addition and recovery tests and analysis of a urine sample used as internal control. Firstly, 7Li, 45Sc, 74Ge, 209Bi 193Ir, 103Rh, 195Pt and 205Tl were evaluated as potential ISs. Thallium was evaluated only for urine samples, once it is analyte in dialysis solution. Tables 2 and 3 show recoveries and relative standard deviations (RSDs) obtained for Al, Ag, As, Be, Cd, Cr, Hg, Pb, Sb, Se and Tl in dialysis solution sample and for As, Cd, Hg and Pb in urine sample, respectively. For dialysis solution, even without matrix matching, IS was not required to accurate determination of

52

Cr,

75

As,

78

Se,

107

Ag,

112

Cd,

121

Sb,

202

Hg,

205

Tl and

208

Pb.

Their recoveries were within the range considered acceptable by AOAC, i.e. from 70 to 125 % [27]. For Ag, there were no improvement in recoveries when using IS, however

10

values obtained without IS are acceptable. The use of 7Li as IS for 9Be led to 104 % recovery and without IS recovery was around 121 %. A significant improvement of recoveries was observed when

193

Ir was used as IS for

27

Al, without IS recoveries

ranged from 189 to 479 % and from 108 to 125 % with IS, except for 2 µg L-1 addition level which is lower than LOQ (5.10 µg L-1). The improvement of recoveries with 7Li as IS for 9Be may be due to the similarity of the mass to charge ratios, m/z. There are divergences in the literature about the choice of the IS for measurements by ICP-MS [28,29]. Some authors reported that a good IS must have similar physico-chemical properties with the analyte, such as the first ionization energy and similarity of isotopic mass analyte-IS [18], others reported that only the similarity of isotopic mass between analyte and IS should be observed for the selection [19,30], and some studies have not tried to rationalize about the choice of IS [13,31]. The explanation about the significant improvement observed here with 27

Al/193Ir pair is not clearly understood, since this pair presents highly different masses

and also different physical-chemical parameters. For urine, best recoveries for for

112

Cd,

202

Hg and

208

75

As were obtained without IS. Better recoveries

Pb were obtained with

209

Bi,

205

Tl and

195

Pt, respectively,

however Tl and Bi may be present in urine samples, thereby Pt was chosen as IS. Better RSDs for Al, Be and Cr in dialysis solution and Cd, Hg and Pb in urine were obtained using IS. Relative standard deviations were lower than 7%. Concentrations determined in internal control urine for As, Cd, Hg and Pb were in agreement with informative values at 95% confidence level (Table 4).

3.4 Analytical performance and application

11

Limits of detection (LOD) and quantification (LOQ) of method were calculated considering standard deviation (SD) for 10 measurements of a blank solution divided by slope of analytical curve multiplied by 3 (LOD) and 10 (LOQ), and then multiplied by the dilution factor. Linear correlation coefficient, slope of analytical curves and LOD obtained for all analytes are shown for dialysis solution and urine samples in Table 5. Linear correlation coefficients close to unity were obtained for all analytes. In Table S2 the effect of dilution gas flow and internal standardization on figures of merit can be observed. Increasing the dilution gas flow rates caused a decrease in sensitivities and LODs may present a marginal increase. However, LODs obtained were below the maximum permitted levels stated in Brazilian legislations, showing that the developed procedure can be applied for quality control of dialysis solutions and monitoring of urine samples for occupational health purposes. After optimization of the main parameters, the procedure was applied for three dialysis solutions and two urine samples (Tables 6 and 7). The concentrations of Cr and Hg in three dialysis solution evaluated were slightly above the maximum permitted levels for RDC regulation and the remaining analytes were lower than respective LODs. As LODs were lower than the maximum permitted levels, all analytes concentrations are according to the RDC. For urine samples, we could not assume if the concentrations determinate were below or above the maximum allowed, because the creatinine content in the samples were not measured.

4. Conclusion

The combination of HMI system, He mode collision cell and internal standardization allowed analysis of complex samples, 2-fold diluted, even without using

12

matrix-matched calibration solutions. The use of HMI makes feasible the introduction of dialysis solutions containing up to 2.6 % m/v TDS and urine samples containing up to 1.4 % m/v TDS without any critical effects on argon plasma, quartz torch, cones interface, lenses and mass spectrometer. Combining HMI, He CCT, and IS, it was developed an analytical procedure for elemental determination of inorganic constituents in dialysis solutions and urine samples by ICP-MS which enabled met the Resolution RDC no. 11 and the Regulatory Standard NR7, respectively. Measurements performed in He mode allowed accurate determinations of elements impaired by spectral interferences, additionally, alkaline solution was efficient to eliminate Hg memory effects and to keep the signal stable for at least 4 h of analysis.

Acknowledgments

The authors are grateful to the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES/PNPD) and to the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq – 141634/2017-0 and 303107/2013-8) for fellowships and financial support. The authors also would like to thank Agilent Technologies for technical support and providing the ICP-MS instrument.

References

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14

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Figure captions Fig. 1. Stability study of Hg signals in ICP-MS in (a) dialysis solution sample and (b) urine sample both fortified with 5 µg L-1 Hg. (○) Washing with 0.12 mol L-1 HCl. (■) Washing with alkaline solution. (–) 5 µg L-1 Hg. (---represents recoveries from 70 to 125%).

18

25

(a)

20

20

15

15

-1

Hg [g L ]

-1

Hg [mg L ]

25

10

5

(b)

10

5

0

0 0

100

200

300

400

Time [min]

500

600

100

200

300

400

500

600

Time [min]

Fig.1

19

Table 1. Operating parameters used in Agilent 7800 Quadrupole ICP-MS. Instrument parameter RF applied power (kW)

Operating conditions 1.55

Plasma gas flow rate (L min-1)

15

-1

Auxiliary gas flow rate (L min )

1.00

-1

Carrier gas flow rate (L min )

1.02

Carrier gas flow rate in HMI

0.42

Dilution gas (L/min) flow for HMI mode Sampling depth (mm) (L/min) He flow rate in collision cell

0.60

Integration Time (s) (mL/min) Nebulizer

3 Concentric nebulizer – glass

Spray chamber

Scott type – double pass

8 4.5

Number of replicates Isotopes monitored

3 9

27

52

75

78

Be, Al, Cr, As, Se, 107Ag, 112Cd, 121Sb, 205Tl, 202

Hg and 208Pb

20

Table 2. Evaluation of combined use of HMI with IS for Ag, Al, As, Be, Cd, Cr, Hg, Sb, Se and Tl determination in dialysis solution by ICP-MS (mean ± standard deviation, n = 3).

Isotope

9

Be

Mode

IS

No gas

7

193

Li

27

Al

No gas

52

Cr

He

NA

As

He

NA

He

NA

No gas

NA

No gas

NA

Sb

No gas

NA

Hg

No gas

NA

Tl

No gas

NA

Pb

No gas

NA

75

78

Se

107

Ag

112

Cd

121

202

205

208

Ir

Added concentration (µg L-1) 2 5 10 2 5 10 2 5 10 2 5 10 2 5 10 2 5 10 2 5 10 2 5 10 2 5 10 2 5 10 2 5 10

Recovery (RSD) (%) Without IS With IS 121 (3.5) 104 (1.8) 121 (2.4) 103 (0.4) 121 (3.1) 104 (2.4) 479 (51.7) 299 (17.9) 222 (4.1) 125 (0.3) 189 (18.1) 108 (9.9) NA 90 (0.7) NA 95 (0.5) NA 101 (0.6) NA 109 (1.4) NA 106 (5.7) NA 105 (3.8) NA 110 (1.6) NA 109 (2.0) NA 110 (2.0) NA 80 (2.8) NA 91 (3.1) NA 120 (4.2) NA 92 (1.8) NA 92 (1.2) NA 92 (0.2) NA 101 (1.7) NA 102 (3.6) NA 101 (0.3) NA 97 (4.2) NA 101 (1.0) NA 96 (0.1) NA 93 9 (1.7) NA 93 (1.4) NA 92 (0.9) NA 95 (1.8) NA 93 (3.2) NA 90 (1.3)

NA - Not Applicable

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Table 3. Evaluation of combined use of HMI with IS for As, Cd, Hg and Pb determination in urine sample by ICP-MS (mean ± standard deviation, n = 3). Recovery (RSD) (%) Isotope Mode IS Added concentration (µg L ) Without IS With IS 2 104 (6.5) NA 75 As He NA 5 110 (5.4) NA 10 102 (1.2) NA 2 76 (4.7) 100 (0.4) 112 195 Cd No gas Pt 5 75 (0.4) 103 (1.2) 10 90 (17.2) 108 (4.5) 2 76 (0.4) 102 (5.6) 202 Hg No gas 195Pt 5 70 (4.3) 98 (5.9) 10 68 (1.3) 82 (1.2) 2 74 (3.3) 97 (2.0) 208 195 Pb No gas Pt 5 74 (1.6) 102 (0.1) 10 84 (5.7) 102 (0.9) NA - Not Applicable -1

22

Table 4. Results for As, Cd, Hg and Pb determination (mean ± SD, µg L-1, n = 3) in internal control urine by ICP-MS. Isotope 75

As Cd 202 Hg 208 Pb 112

Internal control urine (µg L-1) Determined value Reference value 22.03 ± 1.32 18.78 ± 2.82 2.92 ± 0.21 4.84 ± 0.73 18.20 ± 0.40 19.46 ± 4.86 56.40 ± 1.00 50.25 ± 7.54

23

Table 5. Figures of merit for Ag, Al, As, Be, Cd, Cr, Hg, Sb, Se and Tl in dialysis solution and As, Cd, Hg and Pb in urine sample by ICP-MS. Sample

MPL Isotope

Mode

IS

Slope

r

LOD (µg L-1)

Dialysis

9

No gas

7

Dialysis

27

Al

No gas

193

Dialysis

52

Cr

He

45

As

He

Be

Li

0.043

1

0.012

0.4*

Ir

0.100

0.9995

1.70

10*

Sc

0.174

1

0.016

14*

NA

668.57

0.9998

0.025

Dialysis

5* 75

Urine

0.0317**

Dialysis

78

Dialysis

107

Se Ag

He

NA

473.64

0.9997

5.81

90*

No gas

NA

17526.71

0.9912

0.14

5*

NA

7235.38

0.9999

0.010

1*

0.0915

1

0.010

0.012**

NA

15023.64

1

0.016

6*

NA

5819.15

1

0.013

0.2*

0.0728

0.9996

0.011

0.030**

NA

41532.24

1

0.0070

2*

NA

23185.59

1

0.0013

5*

0.799

0.9997

0.0020

27**

Dialysis 112

Cd

No gas 195

Urine Dialysis

121

Sb

No gas

Hg

No gas

Dialysis 202

195

Urine Dialysis

205

Tl

No gas

Dialysis 208

Urine

Pb

Pt

Pt

No gas 195

Pt

*Maximum permitted levels by resolution RDC no. 11 [2]. **Maximum permitted levels by Resolution NR7 [5] calculated assuming the lowest concentration allowed of creatinine in urine (6 mg L-1) and the urine sample volume used. NA - Not Applicable

24

Table 6. Results for Ag, Al, As, Be, Cd, Cr, Hg, Sb, Se and Tl determination (mean ± SD, µg L-1, n = 3) in dialysis solutions (glucose: 1.50, 2.30 and 4.25 % m/v) by ICP-MS. Element 9

Mode

Be No gas 27 Al No gas 52 Cr No gas 75 As He 78 Se He 107 Ag No gas 112 Cd No gas 121 Sb No gas 202 Hg No gas 205 Tl No gas 208 Pb No gas NA - Not Applicable.

IS 7

Li Ir NA NA NA NA NA NA NA NA NA

193

Dialysis solution (µg L-1) 1.50 % 2.30 % 4.25 % <0.012 <0.012 <0.012 <1.70 <1.70 <1.70 0.89 ± 0.02 1.5 ± 0.2 1.91 ± 0.05 <0.025 <0.025 <0.025 <5.81 <5.81 <5.81 0.41 ± 0.05 < 0.145 < 0.145 <0.010 <0.010 <0.010 <0.016 <0.016 <0.016 1.7 ± 0.5 0.8 ± 0.2 0.64 ± 0.07 <0.0070 <0.0070 <0.0070 <0.020 <0.020 <0.020

25

Table 7. Results for As, Cd, Hg and Pb determination (mean ± SD, µg L-1, n = 3) in urine sample by ICP-MS. Element 75

As Cd 202 Hg 208 Pb 112

Urine (µg L-1) Sample 1 Sample 2 1.1 ± 0.1 1.9 ± 0.2 0.034 ± 0.004 0.118 ± 0.006 0.6 ± 0.2 0.7 ± 0.2 0.60 ± 0.06 0.408 ± 0.02

26

Highlights A High Matrix Introduction (HMI) device was successfully applied for analysis of dialysis solutions and urine Bismuth, Ge, Ir, Li, Pt, Rh, Sc and Tl were evaluated as internal standards The combination HMI, collision cell and IS allowed analysis of complex samples

27