DETECTION OF IRRADIATED CHICKEN MEAT BY ANALYSIS OF LIPID EXTRACTS FOR 2-SUBSTITUTED CYCLOBUTANONES USING AN ENZYME-LINKED-IMMUNOSORBENT-ASSAY

The means to detect the irradiation of food has been investigated for many years. In recent times radiolytic products, termed 2-alkylcyclobutanones (2-CBs), have been identified as excellent markers of irradiation in lipid-containing foods. An ELISA test was developed, which was capable of detecting a number of these compounds in irradiated chicken meat. A polyclonal antiserum was raised to a 2-CB containing a terminal carboxyl group conjugated to a carrier protein. This antiserum was highly specific for cyclobutanones containing C-10 and C-12 side chains. During assay validation the limit of detection of the assay was calculated to be 0.064 pg of 2-CB per gram of fat, within- and between-assay variations ranged from 6.7 to 18%. During experimental studies, chicken meat irradiated at doses ranging from 2.5 to 10 kGy were assayed and correctly identified as being treated. Quantitative comparisons between the ELISA and CC-MS revealed a good correlation (r(2) = 0.913) between the two methodologies in concentrations of 2-CB detected in irradiated samples.

Determination of carazolol residues in porcine tissue by radioreceptor assay

A radioreceptor assay was developed for the determination of the p-blocker carazolol in porcine muscle and kidney. The method involves a simple alkaline extraction procedure using diethyl ether followed by a competitive assay between carazolol residues and [H-3]-dihydroalprenolol ([H-3]-DHA) using solubilised beta2-adrenoceptors isolated from a transfected cell line. The limit of detection (LOD) was determined using 20 reference blank samples of pig kidney and pig muscle. LODs for muscle (0.93 mug kg(-1)) and kidney (1.47 mug kg(-1)) were well below their respective European community maximum residue limits, (MRLs 5 and 25 mug kg(-1), respectively). The assay was used to investigate if carazolol residues persisted in pig tissues for up to 30 h post-intramuscular injection at the recommended dose rate (10 mug carazolol/kg body weight). The highest mean +/- S.D. concentrations were detected at 1 h post-injection in kidney (10.84 +/- 1.3 mug kg(-1)) and muscle (3.59 +/- 0.2 mug kg(-1)) which were less than the respective MRLs. It is concluded that this method offers a robust and rapid alternative to other methods for the screening of carazolol residues in pig meat. (C) 2002 Elsevier Science B.V. All rights reserved.

The development of a rapid immunobiosensor screening method for the detection of residues of sulphadiazine

A rapid imununoassay using an optical biosensor (BIAcore(TM)) for determining the presence of sulphadiazine (SDZ) residues in pig bile was developed. SDZ,cas immobilised onto the surface of a dextran-coated silicon chip and a solution containing SDZ antibody, sample and buffer was injected over the chip surface. The level of antibody binding to the chip was determined after 20 s and the surface of the chip was then regenerated over a 1-min period prior to another sample injection taking place. Standard curves were constructed to allow quantification of SDZ presence in sample. Concentrations ranging from 0 to 10.64 mu g ml(-1) SDZ were detected in bile samples taken from experimentally fed pigs and randomly selected pigs taken from a local slaughterhouse. These results were compared to the concentrations of SDZ detected by high-performance liquid chromatography: in associated tissues. When concentrations in bile exceeded 0.6 mu g ml(-1) SDZ, the corresponding edible tissue was above the maximum residue level (MRL), i.e. 0.1 mu g g(-1) in 13 out of 14 cases. Wizen the bile concentration was less than 0.6 mu ml(-1) the associated tissue concentrations never exceeded rite MRL. This experiment has indicated that biosensor analysis of bile is a highly effective method for detecting violative SDZ residues in meat.

The production of pig tissue sulphadimidine reference material

The production of stable homogeneous reference materials containing the antimicrobial agent sulphadimidine in pig tissue is described. These were commissioned by the Community Bureau of Reference (BCR), established by the Commission of the European Communities, to promote improvements in analytical accuracy and to ensure uniformity of results determined by member states. Sulphadimidine-containing tissue powders (400 vials each of muscle, liver and kidney) were prepared by orally dosing pigs with drug, producing lyophilized tissue powders and blending these with negative tissues from unmedicated animals to achieve target concentrations. Details of the production process, the stabilizing procedure developed and the analytical assessments of homogeneity and stability are given.