Determination of Chemical Speciation of 6 Heavy Metals in PM2.5 with Ultrasonic Extraction-Modified BCR Procedure

Ultrasono-extraction was used to substitute the original shaking extraction to extract separately the 4 species (the acid-exchangeable species F1,the reducible species F2,the oxidizable species F3 and the residual species F4) of 6 heavy metals (i.e.,Cu,Zn,Pb,Cd,Ni and Cr) in PM2.5 micro particles by the modified BCR method.ICP-MS was applied to the determination of the 6 metal ions of various chemical species in the extracts.It was shown that the ultrasono-extraction not only requires less time for extraction (requiring only 30 min for F1,F2 and 20 min for F3 instead of 16 h in the original procedure),but also has higher extraction efficiency (amounting to 89.5%-133% as referring to the original procedure),and better precision having values of RSD′s (n=8) for the 6 cations in various chemical species less than 25% and satisfactory accuracy giving relative deviation between values of the total amount (in ng·m-3) of the 4 chemical species and the total amounts (in ng·m-3) of the metals in the sample ranged from -30.7% to -11.5%.