A direct competitive enzyme-linked immunosorbent assay (ELISA) was developed to detect a broad range of (fluoro)quinolones in various matrices. In the optimized generic test, anti-sarafloxacin antibodies in combination with norfloxacin conjugate showed 50% binding inhibition at 0.21 ng mL(-)(1) for sarafloxacin in buffer. Screening for this class of antibiotics is accomplished using a simple, rapid extraction carried out with a 1:1 mixture of methanol and phosphate-buffered saline adjusted to pH 7.4. This common extraction was able to detect 15 (fluoro)quinolone residues such as sarafloxacin, norfloxacin, difloxacin, ciprofloxacin, pefloxacin, ofloxacin, cinoxacin, danofloxacin, enrofloxacin, marbofloxacin, lomefloxacin, enoxacin, flumequine, oxolinic acid, and nalidixic acid in pig kidney, poultry muscle, egg, fish, and shrimp. The assay's detection capabilities (CCbeta) for most of these compounds were <10 microg kg(-)(1) except for the sarafloxacin-, oxolinic acid-, flumequine-, and cinoxacin-spiked matrices, the estimated CCbeta values of which were <4, <25, <100, and <200 microg kg(-)(1), respectively.

Liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis of the tryptic digest of a cleaned-up food matrix extract was used for the detection of milk allergens. The emphasis of this study was on casein, which is the most abundant milk protein and is also considered the most allergenic. A sample cleanup method was developed using an ion exchange column and centriprep device. Cookies spiked with milk powder from 0 to 1250 ppm were extracted, cleaned up, and either digested directly by trypsin or further cleaned up by gel electrophoresis before digestion. The peptide mixture was analyzed on a capillary LC-quadrupole time-of-flight system. Two marker peptides from alphaS1-casein were identified and used for prescreening. The MS/MS data from the mass spectrometry system were processed with Masslynx v4.0 and submitted for database search using either ProteinLynx Global Server or Mascot for protein identification. The LC-MS/MS method, using casein enzyme-linked immunosorbent assay as a reference, was tested on the cookie matrix and was extended to other sample matrices. There were good agreements between the two. This LC-MS/MS method provides a valuable confirmatory method for the presence of casein. It also allows the simultaneous detection of other milk allergens.

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Patulin is a mycotoxin produced by fungal species that frequently grow on fruit and vegetables. It presents risks, particularly for children consuming compotes and fruit juices. Thus, it is important to have methods such as immunoassays to screen a large number of samples. In the relevant literature, previous studies on the production of antibodies against patulin derivatives described qualitative tests for a patulin derivative or showed slight responses. The present study reinvestigated the production of polyclonal antibodies against patulin and their purification since crude antiserum could react non-specifically in immunoassays. Patulin-hemiglutarate was synthesized and conjugated to bovine serum albumin as the immunogen for the immunization of five New Zealand white rabbits. The immunoglobulin G (IgG) fraction was isolated twice by affinity chromatography using Sepharose-LS gel and recombinant G-protein. Classic affinity chromatography using Sepharose-LS gel was unable to eliminate serum albumin from the IgG fraction and the use of recombinant G-protein was efficient to isolate the purified IgG. Titres and specificity were determined by indirect competitive enzyme-linked immunosorbent assay. Patulin-hemiglutarate-ovalbumin gave complete displacement, while patulin displaced 30% of bound antibodies. Thus, a fraction of the antibodies are specific for free patulin. The non-specific binding increased with patulin concentrations. The electrophilic properties of patulin might also induce intermolecular cross-links in vitro that hinder the possibility of responses displacement when free patulin is used.