title: Direct analysis of isopropylthioxanthone (ITX) in milk by high-performance liquid chromatography/tandem mass spectrometry.
abstract: A fast screening method is presented for detecting isopropylthioxanthone (ITX) contamination in milk. The method is based on direct high-performance liquid chromatography/tandem mass spectrometry (HPLC/MS/MS) analysis of milk samples. Sample preparation is limited to the addition of a deuterated ITX solution in acetonitrile that serves both as internal standard and to precipitate proteins. The method is highly accurate and sensitive. Isomeric specific analyses of 2-ITX and 4-ITX are possible at 6 microg/L levels with about 5% precision and accuracy. This approach has been used to check contamination in samples like milk, soy milk, baby milk, in their packaging material. Out of 37 milk samples analyzed, 16 were positive with concentrations ranging from 173-439 microg/L for 2-ITX and from <6 (lower than limit of quantification) to 25 microg/L for 4-ITX.
authors.affiliation: Environmental Health Sciences Department, Istituto di Ricerche Farmacologiche Mario Negri, Via Eritrea 62, 20157 Milano, Italy.
authors.forename: Renzo
authors.initials: R
authors.lastname: Bagnati
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Bianchi
authors.forename: Elena
authors.initials: E
authors.lastname: Marangon
authors.forename: Ettore
authors.initials: E
authors.lastname: Zuccato
authors.forename: Roberto
authors.initials: R
authors.lastname: Fanelli
authors.forename: Enrico
authors.initials: E
authors.lastname: Davoli
mesh_terms: D000097:Acetonitriles / Q000737:chemistry; D000818:Animals; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D004340:Drug Contamination / Q000517:prevention & control*; D008892:Milk / Q000737:chemistry*; D015394:Molecular Structure; D012015:Reference Standards; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D053719:Tandem Mass Spectrometry / Q000379:methods*; D013892:Thioxanthenes / Q000032:analysis / Q000737:chemistry; D044004:Xanthones / Q000032:analysis* / Q000737:chemistry
chemical_list: D000097:Acetonitriles; D013892:Thioxanthenes; D044004:Xanthones; C484911:thioxanthone; C032159:acetonitrile