Detection of Chemicals by a Reporter Immunoassay:  Application to Fluoride

This report describes a concept in which an immunoassay is used indirectly to quantify a nonantigenic very low molecular weight compound participating in a chemical reaction with a haptenic reporter. The detection limit of each reagent is, therefore, governed only by the affinity of the antibodies t...

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Bibliographic Details
Published in:Analytical chemistry (Washington) 2004-08, Vol.76 (15), p.4286-4291
Main Authors: Sagot, Marie-Astrid, Heutte, Florence, Renard, Pierre-Yves, Dollé, Frédéric, Pradelles, Philippe, Ezan, Eric
Format: Article
Language:English
Subjects:
Analytical chemistry
Calibration
Chemical compounds
Chemistry
Chromatography, High Pressure Liquid
Estradiol - analogs & derivatives
Estradiol - analysis
Exact sciences and technology
Fluorides
Immunoassay
Immunoassay - methods
Immunoenzyme Techniques
Indicators and Reagents
Miscellaneous
Trimethylsilyl Compounds
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Summary:This report describes a concept in which an immunoassay is used indirectly to quantify a nonantigenic very low molecular weight compound participating in a chemical reaction with a haptenic reporter. The detection limit of each reagent is, therefore, governed only by the affinity of the antibodies toward the reporter. Fluoride was used as a model, and silylated estradiol was used as a reporter. Upon silylation with N-O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) or N-O-bis(dimethylterbutylsilyl) trifluoroacetamide (MTBSTFA), estradiol is no longer recognized by antibodies specific to estradiol. After reaction with hydrofluoric acid (HF) or fluoride salts (KF, CsF, NaF), its immunoreactivity is restored, and native estradiol is formed and is detected by immunoassay. The level of synthesized estradiol is dependent on the concentration of fluoride. A fluoride detection limit of 0.3 μg/L (15 nM) is obtained. Potential interference with other acids has been eliminated by choosing the silyl group (trimethylsilyl vs tert-butyldimethylsilyl) and by selecting optimal reaction conditions for the desilylation. The method has been applied to the detection of fluoride salts in natural waters (range 0.28−9.0 mg/L) and in an atmosphere artificially contaminated with HF between 8 and 160 μg/m3 in the parts-per-billion range. This indirect immunoassay combines simplicity and high sensitivity and, therefore, can be used in field monitoring. Finally, the extension of the concept to other chemicals is discussed.
ISSN:0003-2700
1520-6882
DOI:10.1021/ac030395f