[Collaborative Study of an LC-MS/MS Method for Determination of Chlorpropham in Feeds].

A collaborative study for validating the determination method of chlorpropham in feeds by LC-MS/MS was conducted in 13 laboratories using 2 kinds of formula feeds, oats, barley, wheat, and corn. The resulting trueness ranged from 75.3 to 87.0%, repeatability and reproducibility in terms of relative standard deviation (RSDr and RSDR) were within 7.3% and 33% respectively, and the HorRat values ranged from 0.39 to 1.5. The limit of detection and limit of quantitation of chlorpropham in feed ware 0.008 mg/kg and 0.003 mg/kg, respectively. This method was thus validated as useful for inspections of chlorpropham in feed.

Detection of ruminant meat and bone meal in feeds by sandwich ELISA with monoclonal antibodies.

A sensitive and reproducible enzyme-linked immunosorbent assay (ELISA) using two monoclonal antibodies directed against a synthetic peptide with an amino-acid sequence related to the C-terminus of bovine myoglobin and the whole molecule of sodium dodecyl sulphate (SDS)-denatured bovine myoglobin was adapted for detecting bovine myoglobin in contaminated feeds. The ELISA employed bovine meat extract of a known myoglobin concentration as a calibration standard and had an limit of detection (LOD) of 3.54 ng/ml and an limit of quantification (LOQ) of 11.0 ng/ml corresponding to 0.022% and 0.067% (wt/wt) bovine meat-and-bone-meal (MBM) mixed in 20-fold-diluted feed extracts, respectively. A cut-off threshold of 20.6 ng/ml bovine myoglobin was set to simplify ELISA and facilitate quick assessment of test results without a tedious calibration process. The ELISA was able to detect bovine MBM in artificially prepared model feeds, mixed botanical feeds, mixed botanical feeds with skimmed milk, fish meal, pork meal and pork/chicken meal at 0.1% (wt/wt). It was also able to detect sheep MBM in test feeds, but showed no reactivity to swine MBM, chicken MBM, skimmed milk or gelatine of bovine origin. The advantages of this method are the quick and easy extraction protocol of proteins from test feeds, using 100 mM sodium sulphide and 0.6% sodium dodecyl sulphate in the extraction solution and the effective detection of bovine and sheep MBM at 0.1% (wt/wt).