Stability of ethyl glucuronide in hair reference materials after accelerated aging.

Two different hair reference materials, one produced from authentic hair displaying an ethyl glucuronide (EtG) content of about 25 pg/mg and one obtained by fortification of blank hair to an EtG level of 85 pg/mg were submitted to accelerated aging between 4 °C and 60 °C for periods between one and 24 months. Subsequently, the EtG content was determined in the aged samples and untreated reference samples stored at -22 °C under repeatability conditions following the so-called isochronous approach. The EtG content remained stable even at 40 °C for 24 months and at 60 °C over six months. This is in contrast to many organic analytes contained in trace concentrations in diverse matrices. A slight but significant increase of the recovered EtG in case of authentic hair samples having been exposed for 24 months between 4 °C and 60 °C may be due to a temperature-driven process that allows increased recoveries of the physiologically embedded EtG.

Synthesis, characterization and application of a two-fold 13C-labeled calibration standard for the analysis of arsenobetaine using HPLC-ESI-MS/MS without high resolution mass spectrometry.

A procedure has been developed for the determination of arsenobetaine in fish matrix by HPLC-ESI-MS/MS. Hereby (trimethylarsonium)-1,2-(13)C-acetate (arsenobetaine) is used as internal calibration standard. Arsenobetaine was determined in a fish material (Sea Bass) with an expanded uncertainty of 3.8%.

Characterisation of commercially available linear alkylbenzenesulfonates by LC-SPE-NMR/MS (liquid chromatography-solid phase extraction-nuclear magnetic resonance spectroscopy-mass spectroscopy).

Commercially available linear alkylbenzenesulfonates (LASs) are a mixture of various homologues and isomers, leading to 20 major species. In this work we investigated the commercial product by liquid chromatography-solid phase extraction-nuclear magnetic resonance spectroscopy-mass spectrometry (LC-SPE-NMR/MS). The commercial product was separated into 17 fractions by liquid chromatography (LC). After chromatographic separation, 5% of the flow was split to a mass spectrometer (MS) while 95% was send to post-column solid phase extraction cartridges for enrichment of the analytes (LC-SPE). After elution from the SPE-cartridges a NMR-spectrometer equipped with a cryo-probe was used for the characterisation of the different LASs species. For the first time (1)H-1D and H-H-COSY spectra for 14 LASs species out of 20 major isomers are presented, whereas the 6 remaining species are detected as mixtures in 3 (1)H-1D and H-H-COSY spectra. These data were used to correlate the chromatographic retention of the LASs isomers to the substitution pattern of the alkyl chain.

Determination of ochratoxin A in wine by liquid chromatography tandem mass spectrometry after combined anion-exchange/reversed-phase clean-up.

Ochratoxin A (OTA) is a mycotoxin produced by Aspergillus ochraceus and Penicillium verrucosum. It has been found and analysed in several foods and feeds. Owing to its toxicity and occurrence in food and feed, the European Community has issued directives and some countries have their own regulations for OTA contents in food, feed and beverages. This work describes a method for the determination of OTA in mulled and red wine. It is based on combined anion exchange/reversed-phase clean-up and was analysed by liquid chromatography coupled with tandem mass spectrometry (multiple reaction monitoring). The method was validated with natural contaminated and spiked wine samples with OTA contents from 1.34 to 3.48 microg kg(-1). Owing to its accuracy, good reproducibility and repeatability, this easy method is a good alternative to liquid chromatography-fluorescence detection methods.