Submitted to: Journal of Agriculture and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/25/2004
Publication Date: 1/12/2005
Citation: Liu, L.S., Chen, G., Fishman, M.L. A single sorbent for tetracycline enrichment and following solid-matrix time-resolved luminescence. 2005. Analytica Chimica Acta:528: p.261-268. Interpretive Summary: The need to find new uses for pectin that is abundant in agricultural by-products, and the need to detect tetracycline (TC) that is an antibiotic accumulating in food chains have prompted us to develop pectin-based matrices for TC analysis. Matrices prepared from calcium cross-linked pectin or C18 chromatography plates are able to act as a sorbent for TC extraction and as a support for TC measurement by time-resolved luminescence. The technology developed in the current study enhances the sensitivity and simplifies the procedure applied for TC analysis, and can be used for routine screening of other analytes in various environments. Furthermore, the study shows the potential applications of pectin in TC isolation and water decontamination. New uses for pectin in citrus byproducts will enhance their value, which will benefit citrus fruit growers and processors. New methods to detect TC in foods and water supplies will benefit all consumers.
Technical Abstract: The aim of this study was to search for a single solid surface that could act as a sorbent in extraction phase for trace chemical enrichment and as a support for solid-matrix time-resolved luminescence (STRL). Four types of solid surfaces were investigated for this purpose using tetracycline as a model analyte. Solid surfaces prepared from pectin and C18 thin-layer chromatography (TLC) plates were able to concentrate TC from very diluted solutions. Europium(III)-tetracycline complex adsorbed on the surface of C18 TLC plates generated the most intensive luminescence when measured at lambda ex = 388 nm and lambda em = 615 nm. This method achieved a 1 ppb limit of detection (LOD) with a 100 microliter sample solution in a repeated spotting mode or 150 microliter sample solution in a static immersion mode. Hyphenation of sorbent extraction and STRL was demonstrated using a single C18 TLC plate. This method is suitable for routine screening of tetracycline in foods or water solutions and can be extended to other ß'diketones in physiological or environmental samples.