Simultaneous determination of lincomycin and spectinomycin residues in animal tissues by gas chromatography-nitrogen phosphorus detection and gas chromatography-mass spectrometry with accelerated solvent extraction.

A new multi-dimensional analytical method using gas chromatography-nitrogen phosphorus detection (GC-NPD) and gas chromatography-mass spectrometry (GC-MS) was developed for qualitative and quantitative measurement of lincomycin and spectinomycin residues in food animal tissues. This method is based on a new extraction procedure using accelerated solvent extraction (ASE). The analytes were extracted by phosphate buffer with trichloroacetic acid deproteinization and clean-up by C₁₈ solid-phase extraction (SPE) adding dodecanesulfonic acid sodium salt as an ion-pair reagent. The eluted fraction was evaporated and derivatised with N,O-bis(trimethylsilyl) trifluoroacetamide (BSTFA) for GC-NPD analysis and GC-MS confirmation. Parameters for extraction pressure, temperature and cycle of ASE, clean-up, derivatisation and analysis procedure were optimised. The method was validated in muscle, kidney and liver of swine, bovine with a low concentration (limit of quantification) of 16.4 and 21.4 µg kg⁻¹ for these two analytes using GC-NPD. For GC-MS, the limits of quantification were 4.1 and 5.6 µg kg⁻¹, respectively. Spiked recoveries from levels of 20 to 200 µg kg⁻¹ were found to be between 73% and 99% with a relative standard deviation (RSD) of less than 17% in GC-NPD. For GC-MS, levels from 5 to 20 µg kg⁻¹ had between 70% and 93% with an RSD of less than 21%. This rapid and reliable method can be used for the characterisation and quantification of residues of lincomycin and spectinomycin in animal tissues.