Development of a Simple Method for the Determination of Toxicologically Relevant Species of Arsenic in Urine Using HG-AAS

Abstract

Humans are exposed to arsenic (As) in the environment, in both organic and inorganic forms, and it has been widely demonstrated that the inorganic arsenic species (arsenate and arsenite) are the main toxic ones being drinking water one of the main sources of exposure worldwide. Urinary arsenic level is the recommended biomarker for assessing human exposure risks. Absorbed inorganic arsenic is metabolized to mono-and dimethylated arsenic compounds (MMA and DMA) prior to its excretion in urine. In this work, a simple procedure for the determination of toxicologically relevant arsenic species in urine (sum of As(III), As(V), MMA and DMA) using Hydride Generation Atomic Absorption Spectrometry (HG-AAS) was developed in order to obtain a feasible and selfsustainable technology for analysis and epidemiological studies when other expensive techniques are not available. Sample preparation was based on the derivation of arsenic species with L-cysteine. The limit of detection was 1.5 µg L-1 , linearity up to 50 µg L-1 and analytical precision was 12 % (relative standard deviation, RSD %, n=10). Trueness was evaluated using spiked urine samples as well as a reference material. The range of acceptation for recoveries was established in 85-115% by means of a t-test at the 95% significance level. Recoveries for the four As species from spiked urine samples were in the range 87.8-113.5 %. The recovery from a reference material was 100.7%. The comparison between the HG-AAS and high performance liquid chromatography-hydride generationcoupled to inductively coupled plasma mass spectrometry (HPLC-HG-ICPMS), considered as a gold standard technique, showed good agreement (R 2 = 0.94) for forty urine samples. The figures of merit were adequate for the determination of relevant species of As for biomonitoring purposes according to international regulations and it can be postulated as an alternative to more expensive techniques.

Necessity of Assessing Biological Exposure to Arsenic Species by Two Representative Analytical Methods

“…The gold standard technique for evaluating As exposure is HPLC-hydride generationcoupled to inductively coupled plasma-mass spectrometry (HPLC-HG-ICP-MS). However, HG-AAS is a cost-effective alternative method for quantifying hAs, namely the sum of AsIII, AsV, MMA, and DMA [15]. This metric is used for As biomonitoring in Korea.…”

“…The overall risk was quantified according to the results of the environmental pollution and impact assessments. First-level (08-11) and second-level (13)(14)(15)(16)(17) abandoned metal mines surveys (AMSs) were performed in the top 10% of 38 regions and in the top 10-40% of 103 mines, respectively (Figure 1). In the present study, second-level AMS data were used.…”

Biomonitoring of arsenic in woodworkers exposed to CCA and evaluation of other non-occupational sources in Uruguay

“…Quantification of the sum of toxicologically relevant species of As in urine (As-U) was performed using an alternative method to HPLC-ICP/MS, technique not available in Uruguay. This method was developed in the CEQUIMTOX using Hydride Generation Atomic Absorption Spectrometry (HG-AAS) as previously reported [30].…”

“…Briefly, the method consists of a pre-reduction step with L-cysteine of As species to As (III) and subsequent determination using HG-AAS (Atomic Absorption Spectrometer Varian SpectrAA 55B) [30].…”

“…Detection limit (LOD, using 3σ criteria) was 1.5 μg L −1 and quantification limit (LOQ, using 10σ criteria) was 5.1 μg L −1 ; precision (RSD %) was 12% and repeatability was in the range from 5.3 to 8.1% (for the highest and lowest concentrations respectively) [30]. Interlaboratory assays obtained from German External Quality Assessment Scheme (G-EQUAS), Institute for Occupational, Environmental and Social Medicine (Erlangen, Germany) are performed twice a year in our laboratory as external quality control, to ensure reliable results.…”