Determination of trace lead in Chinese herbs by derivative flame atomic absorption spectrometry using an atom-trapping technique

A simple and sensitive method is described for the determination of trace lead in Chinese herbs by derivative atom trapping flame atomic absorption spectrometry (D-AT-FAAS) with a modified water-cooled quartz atom-trapping tube. The effects that influence the sensitivity of the derivative method, such as the trap position, the flame conditions and the collection time, were studied. The characteristics of the derivative atom trapping-atomic absorption signal and the linear nature of the working curve were investigated. The sensitivity of the derivative method is 2 or 3 orders of magnitude higher than that of FAAS, and the detection limit improved by 1 or 2 orders of magnitude. Satisfactory recoveries of 93.0 - 108.0% for lead were obtained by determining several Chinese herbs with a relative standard derivation range of 2.9 to 4.2%.