Spectrophotometric determination of trace amounts of hemoglobin using the oxidative decomposition reaction of a copper(II)-phthalocyanine complex.

A catalytic effect of hemoglobin was found in the oxidative decomposition of a copper(II)-phthalocyanine complex (Cu-pts) with peroxomonosulfate. Based on this finding, a simple, rapid, highly sensitive and high-precision spectrophotometric method for hemoglobin was developed. In this indicator system, Cu-pts as the indicator and hemoglobin as the catalyst were simultaneously decomposed with peroxomonosulfate. Therefore, the slopes of the absorbance-time curve of the sample solution become equal to that of the blank solution after 5 min. The calibration curve was linear over the range of 12-258 microg/l. Detection limits (3sigma) were 8.13 microg/l, and the relative standard deviation was 2.05% (10 determinations) for 130 microg/l of hemoglobin. The metal ions did not significantly produce an interference in this method. The albumin had some influence but was permissible up to 6 times the weight of hemoglobin. The proposed method was applied to human blood samples with satisfactory results.