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.

Keywords:

• Chemiluminescence
• Cr(III)
• Dietary supplement
• Flow injection
• Human serum
• Luminol
• Lysozyme
• Pharmaceutical capsules

Acknowledgments

This article is part of a Special Issue on Automated Flow Injection Techniques organized by Dr. Paraskevas Tzanavaras of Aristotelian University of Thessaloniki, Greece.

This work was supported by the National Nature Science Foundation of China (No. 21275118), the Open Funds from the Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, China and Shaanxi Provincial Key Laboratory of Electroanalytical Chemistry, and Northwest University (NWU) Graduate Innovation and Creativity Funds (No. 09YZZ45 and 10YZZ29), China.

Notes

^a diethyldithiocarbamate.

^b 1-(2-pyridylazo)-2-naphthol.

^c 8-hydroxy-7-iodoquinoline-5-sulfonic acid.

^d aminefunctionalized magnetite (Fe₃O₄) microspheres.

^a The average of seven determinations.

^a The average of seven determinations.

^b The content of chromium in the sample.

^c The weight of sample treatment.

^d The average content of chromium in the sample.

^e Not detected.

^a Sample No.1: dietary supplement sample.

^b Sample No.2: spiked human serum sample.