Analysis of Mercury in Sequential Micrometer Segments of Single Hair Strands of Fish-Eaters

Abstract

Although it has been established that mercury (Hg) can be detected in single hair strands using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), calibration remains a challenge due to the lack of well-characterized matrix-matched standards. We concurrently evaluated two strategies for quantifying Hg signals in single hair strands using LA-ICP-MS. The main objective was to obtain time-resolved Hg concentrations in single hair strands of fish-eaters that would correspond to the changes of their body burden over time. Experiments were conducted using hair samples collected from 10 individuals. The first experiment involved the construction of a calibration curve with four powdered hair standard reference materials (SRMs) with a range of Hg concentrations (0.573-23.2 mg/kg). An internal standard, sulfur, as 34S, was applied to correct for ablation efficiency for both the hair strands and the SRMs. Results showed a linear relationship (R2 = 0.899) between the ratio of 202Hg to 34S obtained by LA-ICP-MS and the certified total Hg concentration in the SRMs. Using this calibration curve, average Hg concentrations of 10 shots within a 1-cm segment of a hair strand were calculated and then compared to the total Hg concentrations in the matched 1-cm segment as measured by cold vapor atomic absorption spectrometry (CV-AAS). A significant difference (p < 0.05) was observed. The difference could be attributed to the highly variable ablation/sampling process caused by the use of the laser on the hair powder SRM pellets and the difference in the physical properties of the SRMs. An alternative approach was adopted to quantify consecutive 202Hg to 34S ratios by calibrating the signals against the average Hg concentration of the matched hair segment as measured by CV-AAS. Consecutive daily Hg deposition in single hairs of fish eaters was determined. Results showed that apparent daily changes in Hg concentrations within a hair segment that corresponds to 1 month of hair growth. In addition, a significant decreasing or increasing time-trend was observed. The difference between the minimum and maximum Hg concentration within each individual corresponded to a change of 26-40%. Our results showed that LA-ICP-MS can be used to reconstruct time-resolved Hg exposure in micrometer segments of a single hair strand.

Hair analysis as a biomonitor for toxicology, disease and health status

“…86 In attempts to address the fundamental questions regarding contamination of hair fibers, hairs were sectioned longitudinally and had the outer surface and inner surface analysed with Timeof-Flight Secondary Ion Mass Spectrometry (ToF-SIMS). [158][159][160] This aspect is one of the most impressive approaches of hair analysis with respect to the information withheld by individual strands. In this regard, it is thus possible to section an individual hair and analyse the external surface of the hair and then also the corresponding internal section of the same hair; the primary motivation being to address fundamental questions regarding the influence of longitudinal accumulation of exogenous products on internal concentrations and hence, to infer the integrity of the internal structure, or assess factors regarding decontamination of hair.…”

Fast exchange of strontium between hair and ambient water: Implication for isotopic analysis in provenance and forensic studies

“…Studies on such variation provide opportunities to identify local versus non-local individuals [1], habitat use [2], natal origins of migratory species [3,4], etc. Hair has been used as a biomonitor of trace element exposures such as Hg [5], and Sr isotopes in hair have shown promise for provenance, forensic, and archaeological studies [6][7][8][9][10]. Therefore, understanding the sources of Sr in hair is crucial for the elucidation of environmental or forensic hypotheses.…”

Using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to characterize copper, zinc and mercury along grizzly bear hair providing estimate of diet

“…However, due to its high concentration and homogenous distribution along the length of hair, sulfur was used as the internal standard similar to other studies (Legrand et al, 2004(Legrand et al, , 2007Rodushkin and Axelsson, 2003;Stadlbauer et al, 2005); carbon data will therefore not be further discussed in the manuscript. As there is currently no suitable hair standard for LA-ICP-MS analyses, we attempted to prepare pressed pellets of human hair reference material (IAEA-085 and IAEA-086) for calibration.…”