Pyrolysis coupled with atomic absorption spectrometry for the determination of mercury in Chinese medicinal materials

Abstract

A pyrolysis unit was coupled to an atomic absorption spectrometer for the determination of mercury in solid samples of Chinese medicinal materials (CMMs). This highly sensitive analytical technique provides a simple and rapid method for the screening of Hg in CMM samples including raw herbs, mineral drugs and their derived formulated products. Only 20mg samples were needed and the sensitivity is down to 66pg. The precisions of analyzing solid Hg standard samples and real CM samples were 1.9 and 3–7%, respectively. The recovery of the method was between 97.6 and 102.7% using Hg standard spiked certified reference material of Apple Leaves. No sample pre-treatment was needed and this greatly simplifies the analytical procedure and minimizes potential sources of contamination. Several CM samples were analyzed and the results obtained agreed well with the certified values. The performance of the method was compared with the widely used cold vapor and inductively coupled plasma–mass spectrometry (ICP–MS) methods. Excellent agreements were observed among these methods for Hg levels in the ng region. With the temperature programming capability of the pyrolysis chamber the instrument can potentially be used for the speciation analysis of Hg.