Microwave Digestion - Graphite Furnace Atomic Absorption Spectrophotometry Of Heavy Metals Detected In Traditional Chinese Medicine

The problem of superscale heavy metals in Chinese traditional medicines is widely concerned in recent years. However, no canonical and sensitive methods to determine heavy metals in Chinese traditional medicines are upbuild yet ulteriorly. Through all-round saw about the factors including sampling, raw sample pretreatment, graphite furnace working conditions, sample determination and the so on, a' sensitive, reliable, method for the determination of heavy metals in Chinese traditional medicines was established. The thesis contains five main parts:A representative sampling method was established based on the manufacturing technics and the determination of heavy metals content in different parts of the same sample. It showed that both water honeyed pills and big honeyed pills were homogeneous even though the different appearance between the external and inner parts of the big honeyed pills. The result made the sampling course simple, the only thing needs to be carry about was to prevent the introduction of heavy metals contamination.The pretreatment of raw samples by microwave digestion was investigated. Factors such as grain size, inceptive power, digesting temperature, digesting time were investigated one by one. Each item has some effect on sample digestion, while inceptive power and digesting temperature effect it most. The best digestion condition was then selected: grain size 80, inceptive power 400W, maximum digesting temperature 200 "C, digesting time 20 minute. It can make the digesting course complete.The best working condition of the graphite furnace to determine Cu, Pb, Cd was investigated respectively which emphasized at the optimizing of ashing course. Pb and Cd were prone to volatilize, so that the matrix modifiers must be added in the ashing course for the sake of heightening ashing temperature. After the compare of PdCl2 with NH4H2PO4 for Pb and that of NH4NO3, (NH4)2SO4,NH4H2PO4 for Cd, NH4H2PO4 was selected finally for both Pb and Cd because of its best impact. Cu did not lose until 1000℃, so the matrix modifier was not necessary. Besides, the course ofdrying, atomizing and clearing of graphite tube were also investigated.Combined with the methodology guideline including linear range, detection limit, precision, accuracy, the method set-up was verified. The linear ranges of Cu, Pb, Cd were 0.4~16 ng/mL, 0.7~56 ng/mL, 0.06~1.8 ng/mL, respectively. Detection limits were 0.0842ng/mL, 0.145ng/mL, 0.0 119ng/mL respectively. Experiments of repeatability and recovery showed favorable precision and accuracy.Using the method set-up in front, 62 batches of sample were determined and the conclusion was made. Based on the results, some suggestions on the improving of medicine manufacturing and the prospect of further researching were carried out.