title: Analysis of lasalocid residues in grease and fat using liquid chromatography-mass spectrometry.
abstract: A method for the determination of lasalocid, an antibiotic and coccidiostat, in grease and fat is described. The manufacture of lasalocid produces a grease-like residue as a waste byproduct. Recently this byproduct has been shown to have been illegally introduced into the animal feed chain. Therefore, a quantitative and confirmatory procedure to analyse for lasalocid in this matrix is needed. A portion of grease/oil sample was extracted into hexane-washed acetonitrile, and a portion of the extract was then applied to a carboxylic acid solid-phase extraction (SPE) column for concentration and clean-up. The SPE column was washed with additional hexane-washed acetonitrile and ethyl acetate/methanol, after which lasalocid was eluted with 10% ammoniated methanol. The eluate was evaporated to dryness, redissolved in (1:1) acetonitrile-water and filtered through a PTFE syringe filter. Confirmation and quantitation of lasalocid in the final extract employed a triple quadrupole LC-MS/MS. The method was applied to grease and oil samples containing from 0.02 to 34,000 mg kg(-1) of lasalocid.
authors.affiliation: a Denver Laboratory , US Food and Drug Administration (USFDA) , Denver , CO , USA.
authors.forename: Susan B
authors.initials: SB
authors.lastname: Clark
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Storey
authors.forename: Justin R
authors.initials: JR
authors.lastname: Carr
authors.forename: Mark
authors.initials: M
authors.lastname: Madson
mesh_terms: D000821:Animal Feed / Q000032:analysis; D000900:Anti-Bacterial Agents / Q000032:analysis*; D002853:Chromatography, Liquid / Q000379:methods*; D003049:Coccidiostats / Q000032:analysis*; D004350:Drug Residues / Q000032:analysis; D005223:Fats / Q000737:chemistry; D005506:Food Contamination / Q000032:analysis; D007220:Industrial Waste / Q000032:analysis; D007832:Lasalocid / Q000032:analysis* / Q000096:biosynthesis; D013058:Mass Spectrometry / Q000379:methods*; D009821:Oils / Q000737:chemistry*; D052616:Solid Phase Extraction; D013302:Streptomyces / Q000378:metabolism; D053719:Tandem Mass Spectrometry
chemical_list: D000900:Anti-Bacterial Agents; D003049:Coccidiostats; D005223:Fats; D007220:Industrial Waste; D009821:Oils; D007832:Lasalocid
keywords: LC-MS analysis; animal feed; contamination; lasalocid grease