Point Discharge Optical Emission Spectrometer as a Gas Chromatography (GC) Detector for Speciation Analysis of Mercury in Human Hair

Speciation analysis of mercury in hair facilitates accurate evaluation of mercury exposure to humans and insights into the intertransformation of different mercury species in the human body. However, conventional hyphenated techniques used for mercury speciation analysis usually require expensive instruments and a complex interface. In this work, a compact and miniaturized point discharge (PD) atomic emission spectrometer was utilized as a detector of gas chromatography for the speciation analysis of mercury. Mercury species extracted from hair were derivatized to their volatile species with NaBEt4 and subsequently preconcentrated by headspace solid-phase microextraction (HS-SPME) prior to their speciation analysis. Under the optimized conditions, limits of detection of 0.35 μg kg–1 (0.035 ng) and 1.0 μg kg–1 (0.10 ng) were obtained for IHg and MeHg, respectively, with a relative standard deviation (RSD) of better than 3.5%. Because of the compact and miniature conformation, high excitation capability, low power consumption of PD-OES, and efficient preconcentration of mercury species by HS-SPME, the proposed system not only overcomes the shortcomings associated with the conventional hyphenated techniques but also provides several unique advantages, including significant simplification of experimental setup, reduction of dead volume, and improvement of sensitivity. The accuracy of this system was validated by speciation analysis of mercury in a Certified Reference Material (GBW09101b, human hair) and 10 human hair samples collected from different people in the population.