Determination of Total Chromium in Biological Samples by Automated Reagent Injection Chemiluminescence Analysis

摘要

A sensitive method for the determination of total chromium in real samples by flow injection-chemiluminescence (FI-CL) analysis was proposed. It was found that the CL intensity from luminol-lysozyme reaction could be markedly quenched, and the decrease of CL intensity was linear with the logarithm of Cr(III) concentrations over the range of 5.0 to 4000 pg mL~(-1) with a detection limit of 2.0 pg mL~(-1) (3σ) and relative standard deviations (RSDs) of 3.0, 2.6, and 2.0% for 10, 100, and 1000 pg mL~(-1) Cr(III) (n = 7), respectively. At a flow rate of 2.0 mL min-1, the whole process including sampling and washing could be accomplished within 36 s. The proposed CL method was successfully applied to the determination of total chromium in pharmaceutical capsules, a dietary supplement, and spiked human serum samples, with recoveries from 92.2 to 108.4% and RSDs of less than 4.0%. Using the homemade FI-CL model, the binding constant (K = 4.38 × 106 L mol-1) and the binding sites (n ≈ 1) of Cr(III) to lysozyme were given.