Arsenic speciation in Chinese herb Ligusticum chuanxiong Hort by hydride generation atomic fluorescence spectrometry

Trace arsenic in Ligusticum chuanxiong Hort in the forms arsenite, As(III), arsenate, As(V), and organic arsenic were determined by hydride generation atomic fluorescence spectrometry (HG-AFS). It was observed that As(V) has significant atomic fluorescence that interferes with the signals of As(III) in the 10% HCl matrix. Interferences from heavy metals such as Pb(II) and Cu(II) can cause severe increase of the signals as compared to the insignificant effects caused by Zn(H), Mn(H), Cd(II), and Fe(III). The masking agent 8-hydroxyquinoline was found to be an efficient agent to eliminate interference of transition metals and to remove entirely the atomic fluorescence of As(V) in a mixed As(III)/As(V) solution. A sensitive and interference-free procedure was developed for the arsenic speciation of the Chinese herb samples by use of HG-AFS.