A new rapid treatment of human hair for elemental determination by inductively coupled mass spectrometry†
Advancements in sample preparation for performing elemental analysis are coming from the dissemination of microwave-assisted procedures, but there is still room for improvements by looking for fast and easily applicable procedures. In the present study, open-vessel digestion sample treatment (19–21 °C or 95 °C) was compared with closed-vessel microwave-assisted digestion (180 °C). Detection and quantification limits, accuracy, precision, residual carbon content, and residual acidity were quantified with certified and in-field hair samples. Human hair samples (0.02 g) were digested with HNO3/H2O2 (2 : 1) in an open vessel heated to 95 °C. The residual carbon content was <87 ± 6 mg L−1 and the residual acidity was <0.86 ± 0.10 mol L−1 in the final digested samples. The elements (Al, As, B, Ba, Be, Bi, Ca, Cd, Ce, Co, Cr, Cs, Cu, Fe, Ga, K, La, Li, Mg, Mn, Mo, Na, Nb, Ni, P, Pb, Rb, Sb, Se, Si, Sn, Sr, Te, Ti, Tl, U, V, W, Zn, and Zr) were determined with a quadrupole inductively coupled plasma mass spectrometer equipped with a collision–reaction interface. A detection limit of 0.00002–30 mg kg−1, a (repeatability of <11%, an intermediate precision of <13%, a trueness bias of −4 to 9%, and a recovery of 90–110% for all the elements except for Cr = 65% and Fe = 79% were observed. The results indicate that the proposed method is suitable for routine multi-elemental analysis in human hair studies.