Liquid chromatography-tandem mass spectrometry method for the analysis of N-(3-aminopropyl)-N-dodecylpropane-1,3-diamine, a biocidal disinfectant, in dairy products.

A novel and reliable method to quantify residual levels of N-(3-aminopropyl)-N-dodecylpropane-1,3-diamine in dairy products using ion-pairing reversed-phase liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed and fully validated. Sample extraction was done with salting-out technique using acetonitrile and sodium chloride. For LC-MS/MS, the analyte was detected using positive electrospray ionization (ESI+) and two multiple reaction monitoring (MRM) transitions were monitored.

Liquid chromatography-tandem mass spectrometry multiresidue method for the analysis of quaternary ammonium compounds in cheese and milk products: Development and validation using the total error approach.

Quaternary ammonium compounds (QACs) are both cationic surfactants and biocidal substances widely used as disinfectants in the food industry. A sensitive and reliable method for the analysis of benzalkonium chlorides (BACs) and dialkyldimethylammonium chlorides (DDACs) has been developed that enables the simultaneous quantitative determination of ten quaternary ammonium residues in dairy products below the provisional maximum residue level (MRL), set at 0.1mgkg.

Validation of a liquid chromatography-high-resolution mass spectrometry method for the analysis of ceftiofur in poultry muscle, kidneys and plasma: A unique accuracy profile for each and every matrix.

A robust, selective and specific liquid chromatography-high resolution mass spectrometry (LC-HRMS) method was developed for the quantification of total residues of ceftiofur, an antibiotic belonging to the 3rd generation cephalosporins in plasma, muscle and kidney of poultry. Ceftiofur and conjugates in samples were firstly hydrolyzed with dithioerythritol into desfuroylceftiofur, which was then stabilized by derivatization with iodoacetamide into desfuroylceftiofur acetamide. Sample were then submitted to a solid phase extraction followed the accurate mass analysis of desfuroylceftiofur acetamide by LC-HRMS in full scan mode using a linear trap quadrupole (LTQ)-Orbitrap mass spectrometer with a resolving power 60,000 full width at half maximum (FWHM).

6-Iso-chlortetracycline or keto form of chlortetracycline? Need for clarification for relevant monitoring of chlortetracycline residues in food.

Chlortetracycline (CTC) is a broad-spectrum antibiotic used in veterinary medicine for pulmonary or digestive infections and having a regulatory maximum residue limit (MRL) necessitating an official analytical control method. The purpose of this study was to clarify the identification of different forms of CTC observed in standard solution, in spiked muscle samples and in naturally incurred muscle samples of pigs analysed by LC-MS/MS and to demonstrate the in vivo formation of 6-iso-chlortetracycline and 4-epi-6-iso-CTC as a metabolite of CTC and 4-epi-CTC in muscle. The six following forms were identified, all being isobaric with a protonated molecule at m/z 479 (precursor ion): the keto-enol forms of CTC and the keto-enol forms of 4-epi-chlortetracycline (4-epi-CTC), 6-iso-chlortetracycline (6-iso-CTC) and 4-epi-6-iso-chlortetracycline (4-epi-6-iso-CTC).

Determination of polybromodiphenyl ethers (PBDEs) in milk cream by gas chromatography-mass spectrometry.

An analytical method for polybromodiphenyl ethers (PBDEs) in milk cream has been optimized. The six PBDEs targeted were chosen on criteria of toxicity and occurrence in environmental matrices. Three methods of extraction were tested and compared in terms of lipid recovery yields and repeatability.