Study On The Application On Determinating Content Of Heavy Metalsin Tobacco By Graphite Furnace-Atomic Absorption Spectrophotometry With Microwave Digestion

Smoking has been a social and medicinal problem rifely attended by people and people pay more attention to content of heavy metals in tobacco. Research established a sensitive and reliable method of determination on content of heavy metals in tobacco though all-round saw about the factors including raw sample pretreatment, graphite furnace working conditions, sample determination and so on. Obtained research results as follows:1 The suited conditions of microwave digestion tobacco are HNO3:H2O2(4:1) as digesting solvent,the digesting program is heating up time 5 minutes,enactment temperature 160℃,heat preservation time 5 minutes.2 Due to Pb and Cd are prone to volatilize, the matrix modifiers NH4H2PO4 must be added in the ashing course for the sake of heightening ashing temperature, when determinating Cu,Pb and Cd three heavy metals in graphite furnace-atomic absorption spectrophotometry. The graphite furnace treating conditions with Cu,Pb and Cd three element respectively are: the heating up temperature course of Cu are drying beginning temperature 110℃,ending temperature 120℃,holding time 25 seconds,ashing beginning temperature 700℃,ending temperature 750℃,holding time 20 seconds,atomic best temperature 2100℃, holding time 3 seconds,cleaning temperature 2300℃, cleaning time 3 seconds; the heating up temperature course of Pb are drying beginning temperature 120℃,ending temperature 130℃,holding time 30 seconds,ashing beginning temperature 700℃,ending temperature 750℃,holding time 20 seconds,atomic best temperature 1800℃, holding time 3 seconds,cleaning temperature 2000℃, cleaning time 4 seconds; the heating up temperature course of Cd are drying beginning temperature 110℃,ending temperature 120℃,holding time 50 seconds,ashing beginning temperature 500℃,ending temperature 600℃,holding time 40 seconds,atomic best temperature 1600℃, holding time 3 seconds,cleaning temperature 2200℃, cleaning time 5 seconds.3 It has upper veracity and better repetition determinating content of Cu,Pb and Cd by graphite furnace–atomic absorption spectrophotometry with microwave digestion.The linear ranges of Cu,Pb and Cd are 0.325ng/ml-18ng/ml,0.725 ng/ml-48 ng/ml and 0.060 ng/ml-1.6 ng/ml respectively;detection limits are 0.065 ng/ml,0.145 ng/ml and 0.012 ng/ml.This method has obvious distinguish effects on determinating content of heavy metals in tobacco of different producing areas.