Solution for blank and matrix difficulties encountered during phthalate analysis of edible oils by high performance liquid chromatography coupled with tandem mass spectrometry.
Worldwide production of phthalates has led to their undesirable presence in the food chain. Particularly edible oils have become an area of growing concern owing to numerous reported occurrences of phthalates. The analytical methods used in this field face difficulties associated mainly with matrix complexity or phthalate contamination which this study has aimed to describe and resolve. The proposed procedure consisting of liquid-liquid extraction, solid phase extraction and high performance liquid chromatography coupled with tandem mass spectrometry allowed us to analyze simultaneously 6 individual phthalates and 2 phthalate isomeric mixtures. DSC-18 SPE phase was selected for cleanup owing to the most efficient co-extract removal (assessed using high resolution mass spectrometry). Several sources of phthalate contamination were identified, however, the mobile phase was the most serious. The key improvement was achieved by equipping a contamination trap, a 50-mm reverse phase HPLC column, generating a delay between target and mobile phase peaks of the same compounds. RSDs ranging between 2.4 and 16 % confirm good precision and LOQs between 5.5 and 110μgkg(-1) reflect satisfactory blank management. With up to 19 occurrences in 25 analyzed edible oil samples and levels up to 33mgkg(-1), bis(2-ethylhexyl), diisononyl and diisodecyl phthalates were the most important contaminants.
National Institute of Public Health, Unit for Chemical Safety of Products, Srobarova 48, 100 00 Prague 10, Czech Republic; Department of Analytical Chemistry, Faculty of Science, Charles University in Prague, Albertov 6, 128 43 Prague 2, Czech Republic. Electronic address: adam.vavrous@szu.cz.
Adam
A
Vavrouš
National Institute of Public Health, Unit for Chemical Safety of Products, Srobarova 48, 100 00 Prague 10, Czech Republic.
Jana
J
Pavloušková
National Institute of Public Health, Unit for Chemical Safety of Products, Srobarova 48, 100 00 Prague 10, Czech Republic; Department of Analytical Chemistry, Faculty of Science, Charles University in Prague, Albertov 6, 128 43 Prague 2, Czech Republic.
Václav
V
Ševčík
National Institute of Public Health, Unit for Chemical Safety of Products, Srobarova 48, 100 00 Prague 10, Czech Republic.
Karel
K
Vrbík
Department of Analytical Chemistry, Faculty of Science, Charles University in Prague, Albertov 6, 128 43 Prague 2, Czech Republic; Institute of Forensic Medicine and Toxicology, First Faculty of Medicine, Charles University in Prague and General University Hospital, 121 08 Prague 2, Czech Republic.
Radomír
R
Čabala
D002851:Chromatography, High Pressure Liquid; D007536:Isomerism; D059625:Liquid-Liquid Extraction; D010795:Phthalic Acids / Q000032:analysis*; D010938:Plant Oils / Q000032:analysis*; D015203:Reproducibility of Results; D052616:Solid Phase Extraction / Q000295:instrumentation / Q000379:methods; D021241:Spectrometry, Mass, Electrospray Ionization; D053719:Tandem Mass Spectrometry / Q000295:instrumentation / Q000379:methods
D010795:Phthalic Acids; D010938:Plant Oils; C032279:phthalic acid
Blank problems; Edible oils; High performance liquid chromatography (HPLC); Phthalates; Solid phase extraction (SPE); Tandem mass spectrometry (MS/MS)