COMPARATIVE-STUDY OF 3 DIGESTION METHODS FOR THE DETERMINATION OF CD, CU, AND PB IN CRUDE HERBAL DRUGS PRIOR TO ANALYSIS BY FAAS

A comparison is made of three digestion methods (ashing, wet, and autoclave) for the determination of Cd, Cu, and Pb in crude herbal drugs prior to analysis by flame atomic absorption spectrometry. It was found that the autoclave digestion method combined with the nitric acid decomposition procedure was less time-consuming, safer, and provided best recoveries for the three elements. The detection limit for these elements ranged from 0.8 mug/L for Cd to 209 mug/L for Pb. Linearity (y = 0.999) was shown to be 5 ppm for Cd, 10 ppm for Cu, and 100 ppm for Pb. Repeatability of the analyses was expressed as the coefficient of variation, ranging from 0.72-0.90%. Interference effects were not significant.