Speciation of arsenic in biological samples

Abstract

Speciation of arsenicals in biological samples is an essential tool to gain insight into its distribution in tissues and its species-specific toxicity to target organs. Biological samples (urine, hair, fingernail) examined in the present study were collected from 41 people of West Bengal, India, who were drinking arsenic (As)-contaminated water, whereas 25 blood and urine samples were collected from a population who stopped drinking As contaminated water 2 years before the blood collection. Speciation of arsenicals in urine, water–methanol extract of freeze-dried red blood cells (RBCs), trichloroacetic acid treated plasma, and water extract of hair and fingernail was carried out by high-performance liquid chromatography (HPLC)-inductively coupled argon plasma mass spectrometry (ICP MS). Urine contained arsenobetaine (AsB, 1.0%), arsenite (iAs III, 11.3), arsenate (iAs V, 10.1), monomethylarsonous acid (MMA III, 6.6), monomethylarsonic acid (MMA V, 10.5), dimethylarsinous acid (DMA III, 13.0), and dimethylarsinic acid (DMA V, 47.5); fingernail contained iAs III (62.4%), iAs V (20.2), MMA V (5.7), DMA III (8.9), and DMA V (2.8); hair contained iAs III (58.9%), iAs V (34.8), MMA V (2.9), and DMA V (3.4); RBCs contained AsB (22.5%) and DMA V (77.5); and blood plasma contained AsB (16.7%), iAs III (21.1), MMA V (27.1), and DMA V (35.1). MMA III, DMA III, and iAs V were not found in any plasma and RBCs samples, but urine contained all of them. Arsenic in urine, fingernails, and hair are positively correlated with water As, suggesting that any of these measurements could be considered as a biomarker to As exposure. Status of urine and exogenous contamination of hair urgently need speciation of As in these samples, but speciation of As in nail is related to its total As (tAs) concentration. Therefore, total As concentrations of nails could be considered as biomarker to As exposure in the endemic areas.