STUDY ON THE CHEMILUMINESCENCE REACTION SYSTEM OF Cr(Ⅵ)-LUMINOL-H₂O₂-8-HYDROXYQUINOLINE AND ITS ANALYTICAL APPLICATION

It was found that in an alkaline medium of KOH,the chemiluminescence (CL) reaction between luminol and H2O2 was catalyzed by the complex formed by Cr(Ⅵ) with 8-hydroxyquinoline,and that linear relationship between the intensity of CL and the concentration Cr(Ⅵ) ion was kept in the range of 3.0×10-3 to 4.0×10-2 mg·L-1,having its linear regression equation as ICL=3.6+1.68×106C (g·L-1) with correlation coefficient of 0.999.Detection limit of this method was found to be 1.2×10-3mg·L-1 for Cr(Ⅵ),under the condition of K=3 and confidential level of 99.6%.Test of precision was made at the concentration level of 2×10-2mg·L-1 of Cr(Ⅵ) for 11 multiplicate determinations,and the RSD′s obtained was 2.8%.In the application of this method to the determination of Cr(Ⅵ) in samples of calcium propionate and animal protein powder,results obtained were in consistency with the results obtained by photometry.RSD′s (n=5) found were less than 3.2%,and recovery tested by the standard addition method gave results in the range of 96% to 105%.A brief discussion on the reaction methanism was also given.