One-Step Competitive Immunoassay for Cadmium Ions:  Development and Validation for Environmental Water Samples

Abstract

A rapid, simple, and reliable competitive immunoassay was developed and validated for measurement of Cd(II) in environmental water samples. This assay employed a monoclonal antibody that recognizes Cd(II)-EDTA complexes as capture reagent and a Cd(II)-EDTA conjugate of horseradish peroxidase as an enzyme label. The assay depended on a competitive binding reaction between the enzyme conjugate and Cd(II)-EDTA complexes, derived from the environmental water sample, for the binding sites of the immobilized antibody. The concentration of Cd(II) in the sample was quantified by the ability of its EDTA complexes to inhibit the binding of the enzyme conjugate to the antibody and, subsequently, color formation in the assay. The assay was specific to Cd(II), with a limit of detection of 0.3 ppb. Ca(II), Mg(II), and Fe(III), the metal ions commonly found in ambient water at relatively high concentrations, did not interfere with the assay. Mean analytical recovery of added Cd(II) was 100.29 +/- 3.60. The precision of the assay was satisfactory; coefficients of variation were 3.6-10.9 and 4.81-10.21% for intra- and interassay precision, respectively. The assay compared favorably with graphite furnace atomic absorption spectroscopy in its ability to accurately measure Cd(II) spiked into water samples from a Louisiana bayou.

Facile Synthesis of Galactosamine‐Stabilized Gold Nanoparticles with Sensitive Cd2+ Sensing

“…d-Galactosamine hydrochloride (99 %), hydrogen tetrachloroaurate(III) trihydrate (99.9 %), and sodium hydroxide (96 %) were obtained from Aladdin and used as received. 2 , and Cu(NO 3 ) 2 ·3H 2 O were purchased from Beijing Chemical Reagent Company. Potassium hexacyanoferrate(III) (99 %) and 4-nitrophenol (4-NP) were supplied by Shanghai Chemical Corp. All glassware was cleaned thoroughly with freshly prepared 3:1 HCl/HNO 3 (aqua regia) and rinsed thoroughly with Mill-Q (18.2 MΩ cm -1 ) water before use.…”

“…[1] Experimental and epidemiologic studies provide evidence that chronic exposure to Cd 2+ ions, in combination with other environmental factors, can contribute to an increased risk of cancer. [2][3][4] The standard for the concentration of Cd 2+ ions in drinking water under US and EU guidelines is no more than 44 nm. [5,6] However, the World Health Organization (WHO) standard for the maximum allowable level of inorganic Cd 2+ ions in drinking water is no more than 3 ppb (15 nm).…”

Environmental immunoassays

“…of atrazine and TNT) can be distinguished from sorbed species adding a novel technique to the repertoire of soil scientists who work on the binding of pollutants to humic substances. A sensitive one-step immunoassay for Cd 2+ via an antibody that recognizes Cd(II)-EDTA complexes [7] shows the extension of immunochemical detection via different host/guest systems.…”

Heavy metal removal from waste waters by phosphonate metal organic frameworks

“…Heavy metal contamination in aqueous environment has turn out to be a serious warning due to the rapid increase of industrial and removal activities being highly toxic to living organisms even at low concentrations [1,2]. Among numerous heavy metal ions, chromium is known to be a typical heavy metal contaminant and significantly damages ecosystems.…”