Effective monitoring for ractopamine residues in samples of animal origin by SPR biosensor and mass spectrometry

Ractopamine (RCT) is a member of the beta-2-agonist (beta-agonist) family. It is licensed for use as an animal growth promoter in more than 20 countries worldwide, including the United States and Canada, but is either not licensed or prohibited by over 150 others, including those within the European Union. The issue of the use of RCT in livestock bound for human consumption has risen to prominence recently following the decision by The People's Republic of China to ban the import of pork from a number of processing plants after finding traces of RCT in shipments from the U.S.A.

High-resolution 14C dating of a 25,000-year lake-sediment record from equatorial East Africa

We dated a continuous, ~22-m long sediment sequence from Lake Challa (Mt. Kilimanjaro area, Kenya/Tanzania) to produce a solid chronological framework for multi-proxy reconstructions of climate and environmental change in equatorial East Africa over the past 25,000 years. The age model is based on a total of 168 AMS 14C dates on bulk-organic matter, combined with a 210Pb chronology for recent sediments and corrected for a variable old-carbon age offset. This offset was estimated by i) pairing bulk-organic 14C dates with either 210Pb-derived time markers or 14C dates on grass charcoal, and ii) wiggle-matching high-density series of bulk-organic 14C dates. Variation in the old-carbon age offset through time is relatively modest, ranging from ~450 yr during glacial and late glacial time to ~200 yr during the early and mid-Holocene, and increasing again to ~250 yr today. The screened and corrected 14C dates were calibrated sequentially, statistically constrained by their stratigraphical order. As a result their constrained calendar-age distributions are much narrower, and the calibrated dates more precise, than if each 14C date had been calibrated on its own. The smooth-spline age-depth model has 95% age uncertainty ranges of ~50–230 yr during the Holocene and ~250–550 yr in the glacial section of the record. The d13C values of paired bulk-organic and grass-charcoal samples, and additional 14C dating on selected turbidite horizons, indicates that the old-carbon age offset in Lake Challa is caused by a variable contribution of old terrestrial organic matter eroded from soils, and controlled mainly by changes in vegetation cover within the crater basin.

Characterisation of polyacetylenes isolated from carrot (Daucus carota) extracts by negative ion tandem mass spectrometry

The potential use of negative electrospray ionisation mass spectrometry (ESI-MS) in the characterisation of the three polyacetylenes common in carrots (Daucus carota) has been assessed. The MS scans have demonstrated that the polyacetylenes undergo a modest degree of in-source decomposition in the negative ionisation mode while the positive ionisation mode has shown predominantly sodiated ions and no [M+H](+) ions. Tandem mass spectrometric (MS/MS) studies have shown that the polyacetylenes follow two distinct fragmentation pathways: one that involves cleavage of the C3-C4 bond and the other with cleavage of the C7-C8 bond. The cleavage of the C7-C8 bond generated product ions m/z 105.0 for falcarinol, m/z 105/107.0 for falcarindiol, m/z 147.0/149.1 for falcarindiol-3-acetate. In addition to these product ions, the transitions m/z 243.2 -> 187.1 (falcarinol), m/z 259.2 -> 203.1 (falcarindiol), m/z 301.2 -> 255.2/203.1 (falcarindiol-3-acetate), mostly from the C3-C4 bond cleavage, can form the basis of multiple reaction monitoring (MRM)-quantitative methods which are poorly represented in the literature. The 'MS3' experimental data confirmed a less pronounced homolytic cleavage site between the C11-C12 bond in the falcarinol-type polacetylenes. The optimised liquid chromatography (LC)/MS conditions have achieved a baseline chromatographic separation of the three polyacetylenes investigated within 40 min total run-time. Copyright (C) 2011 John Wiley & Sons, Ltd.

Confirmation of synthetic glucocorticoids with liquid chromatography/mass spectrometry: Organization and results of an international interlaboratory comparison test

Within the framework of a European Union (EU) research project entitled

Mass spectrometry-based metabolomics applied to the chemical safety of food

Mass spectrometry (MS)-based metabolomics is emerging as an important field of research in many scientific areas, including chemical safety of food. A particular strength of this approach is its potential to reveal some physiological effects induced by complex mixtures of chemicals present at trace concentrations. The limitations of other analytical approaches currently employed to detect low-dose and mixture effects of chemicals make detection very problematic. Besides this basic technical challenge, numerous analytical choices have to be made at each step of a metabolomics study, and each step can have a direct impact on the final results obtained and their interpretation (i.e. sample preparation, sample introduction, ionization, signal acquisition, data processing, and data analysis). As the application of metabolomics to chemical analysis of food is still in its infancy, no consensus has yet been reached on defining many of these important parameters. In this context, the aim of the present study is to review all these aspects of MS-based approaches to metabolomics, and to give a comprehensive, critical overview of the current state of the art, possible pitfalls, and future challenges and trends linked to this emerging field. (C) 2010 Elsevier Ltd. All rights reserved.

Screening and Quantitative Confirmatory Method for the Analysis of Glucocorticoids in Bovine Milk Using Liquid Chromatography-Tandem Mass Spectrometry

An LC/MS/MS method was developed and validated for the simultaneous identification, confirmation, and quantification of 12 glucocorticoids in bovine milk. The method was validated in accordance with the criteria defined in Commission Decision 2002/657/EC. The developed method can detect and confirm the presence of dexamethasone, betamethasone, prednisolone, flumethasone, 6 alpha-methylprednisolone, fluorometholone, triamcinolone acetonide, prednisone, cortisone, hydrocortisone, clobetasol propionate, and clobetasol butyrate in bovine milk. Milk samples are extracted with acetonitrile; sodium chloride is subsequently added to aid partition of the milk and acetonitrile mixture. The acetonitrile extract is then subjected to liquid-liquid purification by the addition of hexane. The purified extract is evaporated to dryness and reconstituted in a water acetonitrile mixture, and determination is carried out by LC/MS/MS. The method permits analysis of up to 30 samples in 1 day.

Development of a rapid, multi-class method for the confirmatory analysis of anti-inflammatory drugs in bovine milk using liquid chromatography tandem mass spectrometry

A rapid liquid chromatography tandem mass spectrometry (LC-MS/MS) method has been developed and validated for the simultaneous identification, confirmation and quantitation of seven licensed anti-inflammatory drugs (AIDS) in bovine milk. The method was validated in accordance with the criteria defined in Commission Decision 2002/657/EC. Two classes of AIDS were investigated, corticosteroids and non-steroidal anti-inflammatory drugs (NSAIDs). The developed method is capable of detecting and confirming dexamethasone (DXM), betamethasone (BTM), prednisolone (FRED), tolfenamic acid (TV), 5-hydroxy flunixin (5-OH-FLU). meloxicam (MLX) and 4-methyl amino antipyrine (4-MAA) at their associated maximum residue limits (MRLs). These compounds represent all the corticosteroids and NSAIDs licensed for use in bovine animals producing milk for human consumption. These compounds have never been analysed before in the same method and also 4-methyl amino antipyrine has never been analysed with the other licensed NSAIDs. The method can be considered rapid as permits the analysis of up to 30 samples in one day. Milk samples are extracted with acetonitrile; sodium chloride is added to aid partition of the milk and acetonitrile mixture. The acetonitrile extract is then subjected to liquid-liquid purification by the addition of hexane. The purified extract is finally evaporated to dryness and reconstituted in a water/acetonitrile mixture and determination is carried out by LC-MS/MS. Decision limit (CC alpha) values and detection capability (CC beta) values have been established for each compound. (C) 2009 Elsevier B.V. All rights reserved.

Confirmatory method for the determination of various acetylgestagens in animal kidney fat using liquid chromatography-tandem mass spectrometry

A confirmatory method has been developed and validated that allows for the simultaneous detection of medroxyprogesterone acetate (MPA), megestrol acetate (MGA), melengestrol acetate (MLA), chlormadinone acetate (CMA) and delmadinone acetate (DMA) in animal kidney fat using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The compounds were extracted from kidney fat using acetonitrile, defatted using a hexane wash and subsequent saponification. Extracts were then purified on Isolute CN solid-phase extraction cartridges and analysed by LC-MS/MS. The method was validated in animal kidney fat in accordance with the criteria defined in Commission Decision 2002/657/EC. The decision limit (CC) was calculated to be 0.12, 0.48, 0.40, 0.63 and 0.54 g kg-1, respectively, for MPA, MGA, MLA, DMA and CMA, with respective detection capability (CC) values of 0.20, 0.81, 0.68, 1.07 and 0.92 g kg-1. The measurement uncertainty of the method was estimated at 16, 16, 19, 27 and 26% for MPA, MGA, MLA, DMA and CMA, respectively. Fortifying kidney fat samples (n = 18) in three separate assays showed the accuracy of the method to be between 98 and 100%. The precision of the method, expressed as % RSD, for within-laboratory reproducibility at three levels of fortification (1, 1.5 and 2 g kg-1 for MPA, 5, 7.5 and 10 g kg-1 for MGA, MLA, DMA and CMA) was less than 5% for all analytes.

Development and validation of a method for the confirmation of halofuginone in chicken liver and eggs using electrospray tandem mass spectrometry

A method is described for the quantitative confirmation of halofuginone (HFG) residues in chicken liver and eggs. This method is based on LC coupled to positive ion electrospray MS-MS of the tissue extracts, prepared by trypsin digestion of the tissues followed by liquid-liquid extraction and final clean-up using Solid Phase Extraction (SPE). The [M+H](+) ion at m/z 416 is monitored along with four transitions at m/z 398, 138, 120 and 100. The method has been validated according to the draft EU criteria for the analysis of veterinary drug residues at 15, 30 and 45 mug kg (-1) in liver and 5, 15 and 50 mug kg (-1) in eggs. The new analytical limits, CCalpha and CCbeta were calculated for liver and were 35.4 and 43.6 mug kg (-1), respectively. (C) 2003 Elsevier Science B.V. All rights reserved.

Femtosecond lasers for mass spectrometry: Proposed application to catalytic hydrogenation of butadiene

Mass spectra from the interaction of intense, femtosecond laser pulses with 1,3-butadiene, 1-butene, and n-butane have been obtained. The proportion of the fragment ions produced as a function of intensity, pulse length, and wavelength was investigated. Potential mass spectrometry applications, for example in the analysis of catalytic reaction products, are discussed.