Study on colour reaction of xylenol orange with Pb(II) complex and its application

Aim The purpose of the experiment is to find new methods for the determination of lead in solution.Methods Based on the fact that clear colour reaction occurs when Pb(Ⅱ)and Xylenol Orange(XO)form the chelate Pb-XO in solution,the spectrophotometry may be used to determine micro-lead in solution by measuring the chelate.Results Pb(Ⅱ)and XO form the chelate PbXO at pH=6.0±0.1 in solution,the maximum wavelength of PbXO solution was at 535 nm.Beer's law was obeyed in the range of 0~4.0 mg/L,i.e.A=1.33×10-3+1.936mPb,R=0.999 7.The detection limit was 0.05 mg/L,molar absorption coefficient e was 2.0×104 L·mol-1·cm-1.The relative error(RE)of determining results was no larger than 0.78%(RE≤0.78%),the recovery of Pb(Ⅱ)was in the range of 96.92%～103.8%.Conclusion The method of determining Pb(Ⅱ)in solution is simple,easy and accurate.It can take the place of atomic absorption spectroscopy for determining lead in solution,and it has general applicability and is beneficial to popularization.