单晶硅原料溶于浓氢氟酸中，基体硅以SiF4形式挥发除去.残渣溶于硝酸及盐酸中，再加高氯酸并蒸发至近干,残渣用盐酸(1+1)使其完全溶解.分取部分试液，在pH 4.5的六胺缓冲介质中用吐温-20，PAR及(NH4)2SO4，在总体积为10 mL的溶液中进行萃取.经过萃取可分离除去全部共存的Fe(Ⅲ),Cu(Ⅱ),Cr(Ⅲ)及Ni(Ⅱ)，部分钴(Ⅱ)和铅(Ⅱ)，而Al(Ⅲ)则与Ca(Ⅱ)，Mg(Ⅱ)及Na(Ⅰ)定量地留在下层水相中.用分光光度法在CPC存在下，CAS为显色剂测定下层水相中铅含量，光度测定波长为642 nm，方法的线性范围为0.02~0.50 mg·L-1，检出限为0.01 mg·L-1也试验了方法的回收率及精密度，所测得回收率在96%~101%之间，相对标准偏差(n=5)均小于3.5%.

Sample of elementary silicon was dissolved in conc.HF and the matrix silicon was expelled by volalitalization as SiF4↑.The residue was taken up with HNO3 and HCl and evaporated to near dryness by fuming with HClO4.After dissolving the residue with HCl(1+1),an aliquot of the solution was taken and extracted with Tween-20,PAR and (NH4)2SO4 in a total volume of 10 mL at pH 4.5 buffered with hexamine,to remove all of the co-existing Fe(Ⅲ),Cu(Ⅱ),Cr(Ⅲ) and Ni(Ⅱ),part of Co(Ⅱ) and Pb(Ⅱ),while Al(Ⅲ) remained quantitatively in the lower aqueous phase together with Ca(Ⅱ),Mg(Ⅱ) and Na(Ⅰ).Aluminum(Ⅲ) in the lower phase was determined spectrophotometrically with chrome azurol S at pH 4.5 in the presence of CPC.Linear relationship between the absorbance measured at 642 nm and the concentration of Al(Ⅲ) was obtained in the range of 0.02-0.50 mg·L-1,with detection limit of 0.01 mg·L-1.Recovery was tested by the standard addition method,the results obtained were in the range from 96% to 101%.Values of RSD′s (n=5) found were less than 3.5%.