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

Abstract

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.