Application of Inductively Coupled Plasma Mass Spectrometry Multielement Analysis in Fingernail and Toenail as a Biomarker of Metal Exposure

Abstract

The application of inductively coupled plasma mass spectrometry (ICP-MS) to multielement analysis in fingernail and toenail as biological indices for metal exposure is presented. The ICP-MS measurements were performed using a Thermo Elemental X7CCT series. Fingernail specimens were obtained from 130 healthy volunteers, and paired fingernail and toenail samples from 50 additional healthy volunteers of both sexes were collected as well. After warm water and acetone decontamination, 20 mg fingernails and toenails were acid mineralized after a decontamination procedure, and 32-34 elements were simultaneously quantified after acid dilution following water calibration. Li, Be, B, Al, V, Cr, Mn, Co, Ni, Cu, Zn, Ga, Ge, As, Se, Rb, Sr, Mo, Pd, Ag, Cd, Sn, Sb, Te, Ba, La, Gd, W, Pt, Hg, Tl, Pb, Bi, and U could be validated in fingernail and toenail samples. Linearity was excellent, and the correlation coefficients were above 0.999. Quantification limits ranged from 0.04 pg/mg or ng/g (U) to 0.1 ng/mg or microg/g (B). Because of the lack of available certified nail reference material, an adequate quality assessment scheme was ensured by comparison with an interlaboratory nail-testing procedure, and the results showed optimal consistency for elements tested. Results are presented and compared with published multielement data. Six cases of domestic exposure to lead were diagnosed based on fingernail analysis. Application of ICP-MS multielement analysis in fingernail and toenail as a biomarker of metal and nonmetal exposure permits greater noninvasive control of industrial, domestic, or environmental exposure and is very useful for epidemiological studies.