Determination of lead in botanicals/Chinese prepared medicines by using microwave digestion with flow injection-inductively coupled plasma-mass spectrometry

A simple, sensitive, and rapid method was developed for the determination o f lead in botanicals and Chinese prepared medicines (CPM) by using closed-v essel microwave digestion with flow injection-inductively coupled plasma-ma ss spectrometry. The limits of detection and quantitation for the method, b ased on 0.5 g digested sample, were calculated to be 0.10 and 0.61 mg/kg, r espectively. A simple approach was proposed for calibration by multiple lin ear regression (MLR) with Pb-207, Pb-206, and Pb-204 for the determination of lead in botanical and CPM samples. The results from calibration by MLR w ere compared with those obtained by conventional modes using Pb-207 and the sum of Pb-207 and Pb-206. Th, results obtained by the different modes of c alibration were in good agreement for botanical and CPM samples. The method was found to have good accuracy for the analysis of botanical reference ma terials. Method precision based on analyses of different types of CPM sampl es by different analysts on different days for different levels of lead was between 3.0 and 8.0 % (relative standard deviation, n = 6). The effect of possible matrix interference caused by nitric acid and the extent of digest ion was investigated with the method of standard additions. Significant mat rix interference was not observed for the CPM samples analyzed. MLR was use d to examine the effect of variation in isotopic abundance, which was found to present no significant problem in the determination of lead in the bota nical and CPM samples.