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Development of a chemiluminescent enzyme immunoassay to detect cadmium in cereal samples

Xiao, Zhi-Li, Tian, Wei, Xu, Zhen-Lin, Sun, Yuan-Ming
Food and agricultural immunology 2018 v.29 no.1 pp. 1184-1196
brown rice, cadmium, calcium, chemiluminescence, copper, corn, enzyme immunoassays, glutinous rice, gold, inhibitory concentration 50, iron, lead, magnesium, manganese, mercury, metal ions, peroxidase, silver, wheat, zinc
In this study, we develop a sensitive indirect competitive chemiluminescent enzyme immunoassay (ic-CLEIA) to detect cadmium (Cd) in cereals. A luminol-hydrogen peroxide chemiluminescence system catalysed by horseradish peroxidase (HRP) was used as the signal detecting system. The method showed a half-maximal inhibition concentration (IC₅₀) of 0.5 ng/mL and a limit of determination (LOD) of 0.06 ng/mL. The assay indicated an effective linear range from 0.16 to 1.56 ng/mL. There were no obvious cross-reactivities with other metal ions, including Hg²⁺, Pb²⁺, As²⁺, Ag⁺, Fe³⁺, Cu²⁺, Cr²⁺, Au³⁺, Ca²⁺, Mg²⁺, Mn²⁺ and Zn²⁺. Recovery rates ranged from 79.2% to 120.0% for rice, maize, wheat, brown rice and glutinous rice samples. Twenty-five practical cereal samples were analysed, and the comparative analysis of the results showed a strong correlation (r = 0.984) between the CLEIA and the GFAAS methods. The results indicated that the ic-CLEIA developed was acceptable to screen for cadmium in cereal samples.