Chemical modification for sulfur determination in human hair by high-resolution continuum source graphite furnace molecular absorption spectrometry

Abstract

This paper presents the study of chemical modification for sulfur determination in human hair samples by high-resolution continuum source molecular absorption spectrometry in a graphite furnace (HR-CS GF MAS) via molecular absorption of CS. The thermal behavior of inorganic and organic S species was studied without and with the use of chemical modifiers. Without chemical modification, sulfur species were lost in the pyrolysis step, especially when using organic standards. The combination of a mixture of modifiers Pd + Mg (15 + 10 μg) in solution and W (800 μg) as a permanent modifier allowed the accurate determination of S in hair samples at 900 °C pyrolysis and 2400 °C vaporization temperatures, by using an inorganic sulfur standard for constructing the calibration curve. Accuracy was checked by the analysis of the certified reference material NSC DC73347a (human hair), with the recovery of the certified value better than 98%. The results obtained for 14 human hair samples by the proposed method were in agreement with those obtained by ICP OES, according to the paired t-test, with a 95% level of confidence.