Analytical Sciences

Time-resolved Chemiluminescence Technique for the Microdetermination of Proteins Based on Their Complexation with Copper(II)

Zheng Ping LI,* Shuang Shuang FAN,** Li Na ZHANG,* and Feng Chi WANG***

*College of Chemistry and Environment Science, Hebei University, Baoding 071002, Hebei Province, P. R. China
**Department of Chemistry, Chengde Teacher’s College for Nationalities, Chengde 067000, Hebei Province, P. R. China
***Hebei Entry and Exit Inspection and Quarantine Bureau of P. R. China, Shijiazhuang 051000, Hebei Province, P. R. China

Based on the complexation between proteins and Cu(II) coupled with the time-resolved chemiluminescence (CL) technique, a highly sensitive and quantitative assay for measuring proteins in solution is described. The complexes of proteins with Cu(II) have a strongly catalytic effect on the luminol-H₂O₂ CL reaction. Because the CL emission produced by the complexes is much more long-lived than that by Cu(II), the CL signals originating from proteins can be easily identified and measured with a time-resolved technique. On this basis, bovine albumin fraction V (BAF V) can be quantitatively determined in the range of 0.01 - 5.0 µg/ml with a detection limit of 5.8 ng/ml. The results show that the proposed assay exhibits a small variation in the response values for the same amount of different proteins, as compared to the Lowry as well as Bradford assays. The CL assay has also been studied for the detection of immobilized proteins.

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