ARSENIC DETERMINATION IN URINE USING HG-MIP OES: A TOXICOLOGYCAL APPLICATION

BÜHL, V.; PIZZORNO, P.; FALCHI, L.; CORA JOFRE, F.; SAVIO M.; MAÑAY, N.; PISTÓN, M.

Simposio; 15th Rio Symposium on Atomic Spectrometry; 2019

Humans are exposed to arsenic (As) in the environment, in both organic and inorganic forms, and it has been widely demonstrated that the inorganic As (i-As) species (arsenate and arsenite) are the main toxic ones. People can be exposed to i-As through drinking water, industrial processes, eating food and smoking tobacco. Absorbed i-As is partially metabolized to mono- and dimethylated As compounds (MMA and DMA). Humans excrete a mixture of i-As, MMA and DMA in the urine, called toxicologically relevant As species. Urinary As level is the recommended biomarker for assessing human exposure risks and for occupationally exposed workers it should be less than 35 μg L-1[1].A simple procedure for relevant As species determination in urine was developed. Sample preparation was based on dilution with ultrapure water (1:1) and As species pre reduction with L-cysteine. Matrix-matched calibration was used. Analytical determinations were performed at 193.695 nm on an Agilent 4210 microwave induced plasma optical emission spectrometer (MIP OES) equipped with a standard torch and a multimode spray chamber for hydride generation (MSIS, Agilent). The reductant agent for hydride generation (HG) was NaBH4 2% (w/v) in NaOH 0.5 % (w/v). MIP OES operating conditions were 0.55 L min-1 N2 flow rate; 30 rpm pump speed; viewing position 30; 10 s read time. The main figures of merit were LOD 1.5 µg L-1, linearity was studied up to 100 µg L-1 and analytical precision was 8 % (RSD %, n=10). Trueness was evaluated using spiked urine samples as well as an external quality assessment scheme with recoveries between 80 - 120 %. The comparison between HG-MIP OES and the method used in routine analysis (HG-AAS), showed good agreement for thirty urine samples of exposed workers (slope 1.103 and intercept 0.451). Results showed that this method is suitable for proper biomonitoring for both exposed workers and general population and could be an alternative to HG-AAS.