Application of enzymatic hydrolysis for the isolation of titanium dioxide nanoparticles from human hair for sp-ICP-MS analysis.

Abstract

The widespread use of inorganic nanoparticles (NPs) is a growing concern due to their potential toxic effects on the environment and living organisms. The first step in determining exposure levels in humans is to establish the presence of these emerging pollutants in biological samples of human origin. Recent studies have investigated the presence of NPs in common biological fluids, but the presence of NPs in hair has not yet been explored. Challenges arise due to the low levels of NPs in human biological specimens, and because sample pretreatments must guarantee the stability of the isolated NPs. This study focuses on the development of a method for detecting titanium dioxide nanoparticles (TiO2 NPs) in human hair. To release these nanoparticles from the hair's keratin matrix, enzymatic hydrolysis has been explored (3.0 mL of a 4.0 mg mL-1 pancreatin solution at pH 7.4, 37 °C, orbital shaking at 200 rpm, 12 h). The TiO2 NPs were assessed using single particle inductively coupled plasma-mass spectrometry. The developed method has been found to be robust (limit of detection of 23 NPs mg-1, limit of detection in size of 25 nm, and overall precision of the method lower than 10%). The applicability of the method was further demonstrated by analysis of several hair samples. The found contents varied from 4.4 × 105 to 6.8 × 106 TiO2 NPs g-1 (TiO2 NPs mass concentration from 10 to 173 ng g-1) which implied percentages of titanium as TiO2 NPs between 3 and 31%.

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