Screening of stereoisomeric chloramphenicol residues in honey by ELISA and CHARM ® II test - the potential risk of systematically false-compliant (false negative) results.

Chloramphenicol (CAP) is a broad-spectrum antibiotic used widely both in human and in veterinary medication but due to adverse health effects is not authorised anymore for use in food-producing animals in many countries. CAP molecule contains two asymmetric centers resulting in four para-CAP stereoisomers, but only the RR-CAP enantiomer is bioactive with significant antimicrobial activity. In this study the detection of the four CAP stereoisomers was tested by five commercial ELISA kits and the Charm® II Chloramphenicol Test.

Development of an LC-MS/MS method for studying migration characteristics of acetaldehyde in polyethylene terephthalate (PET)-packed mineral water.

During storage, acetaldehyde migration from polyethylene terephthalate (PET) bottles can affect the quality of mineral water even in the low µg l(-1) range negatively, as it features a fruity or plastic-like off-flavour. For a sensitive and fast analysis of acetaldehyde in mineral water, a new analysis method of 2,4-dinitrophenylhydrazine (DNPH) derivatisation followed by HPLC-electrospray tandem mass spectrometry (ESI-MS/MS) was developed. Acetaldehyde was directly derivatised in the mineral water sample avoiding extraction and/or pre-concentration steps and then analysed by reversed-phase HPLC-ESI-MS/MS using multiple reaction monitoring mode (MRM).

Rapid determination of the attenuation limit of beer using middle-infrared (MIR) spectroscopy and a multivariate model.

A new approach for the determination of the attenuation limit of beer samples using the specific fingerprint region of middle-infrared (MIR) spectroscopy in combination with multiple regression by partial least-squares (PLS) was developed using an attenuated total reflectance (ATR) module. A specific spectral region between 1200 and 800 cm(-1) was identified as highly informative for the quantification of the limit of attenuation. The absorptions in this region are induced by vibrational bands of ethanol (1080, 1040, and 880 cm(-1)) and dissolved extract, in majority maltotriose (1160-1140 and 1040-980 cm(-1)).

Determination of alcohol and extract concentration in beer samples using a combined method of near-infrared (NIR) spectroscopy and refractometry.

A new approach of combination of near-infrared (NIR) spectroscopy and refractometry was developed in this work to determine the concentration of alcohol and real extract in various beer samples. A partial least-squares (PLS) regression, as multivariate calibration method, was used to evaluate the correlation between the data of spectroscopy/refractometry and alcohol/extract concentration. This multivariate combination of spectroscopy and refractometry enhanced the precision in the determination of alcohol, compared to single spectroscopy measurements, due to the effect of high extract concentration on the spectral data, especially of nonalcoholic beer samples.

Selective determination of hydrogen peroxide by adduct formation with a dinuclear iron(III) complex and flow injection analysis/tandem mass spectrometry.

A highly selective method for the determination of hydrogen peroxide is presented. In a flow injection analysis (FIA) instrument, the analyte is brought into contact with a dinuclear heptadentate iron(III) complex. The formation of the peroxide adduct is quantified using electrospray tandem mass spectrometry (ESI-MS/MS).