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Kaufmann A.,Official Food Control Authority
TrAC - Trends in Analytical Chemistry | Year: 2014

The coupling of ultra-high-performance liquid chromatography (UHPLC) with high-resolution mass spectrometry (HRMS) has been well received within the analytical community. Both technologies have experienced significant advances in recent years. Not only have the resolution power and sensitivity improved, but the increased robustness, which includes prolonged column lifetime, extended dynamic range, easier mass calibration, and enhanced software handling capabilities, is making this coupling more attractive to a larger user base. In this article, we discuss possibilities and current limitations of the UHPLC-HRMS coupling. We also review the application of UHPLC-HRMS in a variety of fields, where it has been widely accepted or where we anticipate more extensive use in the near future. © 2014 Elsevier B.V. Source


Kaufmann A.,Official Food Control Authority | Kaufmann A.,Kantonales Labor Zurich
Analytical and Bioanalytical Chemistry | Year: 2012

High-resolution mass spectrometry (HRMS), which is used for residue analysis in food, has gained wider acceptance in the last few years. This development is due to the availability of more rugged, sensitive, and selective instrumentation. The benefits provided by HRMS over classical unit-mass-resolution tandem mass spectrometry are considerable. These benefits include the collection of full-scan spectra, which provides greater insight into the composition of a sample. Consequently, the analyst has the freedom to measure compounds without previous compound-specific tuning, the possibility of retrospective data analysis, and the capability of performing structural elucidations of unknown or suspected compounds. HRMS strongly competes with classical tandem mass spectrometry in the field of quantitative multiresidue methods (e.g., pesticides and veterinary drugs). It is one of the most promising tools when moving towards nontargeted approaches. Certain hardware and software issues still have to be addressed by the instrument manufacturers for it to dislodge tandem mass spectrometry from its position as the standard trace analysis tool. © Springer-Verlag 2012. Source


Kaufmann A.,Official Food Control Authority
Rapid Communications in Mass Spectrometry | Year: 2010

Elemental compositions (ECs) can be elucidated by evaluating the high-resolution mass spectra of unknown or suspected unfragmented analyte ions. Classical approaches utilize the exact mass of the monoisotopic peak (M + 0) and the relative abundance of isotope peaks (M + 1 and M + 2). The availability of high-resolution instruments like the Orbitrap currently permits mass resolutions up to 100000 full width at half maximum. This not only allows the determination of relative isotopic abundances (RIAs), but also the extraction of other diagnostic information from the spectra, such as fully resolved signals originating from 34S isotopes and fully or partially resolved signals related to 15N isotopes (isotopic fine structure). Fully and partially resolved peaks can be evaluated by visual inspection of the measured peak profiles. This approach is shown to be capable of correctly discarding many of the EC candidates which were proposed by commercial EC calculating algorithms. Using this intuitive strategy significantly extends the upper mass range for the successful elucidation of ECs. © 2010 John Wiley & Sons, Ltd. Source


Borras S.,University of Barcelona | Kaufmann A.,Official Food Control Authority | Companyo R.,University of Barcelona
Analytica Chimica Acta | Year: 2013

Monitoring of common diagnostic fragments is essential for recognizing molecules which are members of a particular compound class. Up to now, unit resolving tandem quadrupole mass spectrometers, operating in the precursor ion scan mode, have been typically used to perform such analysis. By means of high-resolution mass spectrometry (HRMS) a much more sensitive and selective detection can be achieved. However, using a single-stage HRMS instrument, there is no unequivocal link to the corresponding precursor ion, since such instrumentation does not permit a previous precursor selection. Thus, to address this limitation, an in silico approach to locate precursor ions, based on diagnostic fragments, was developed. Implemented as an Excel macro, the algorithm rapidly assembles and surveys exact mass data to provide a list of feasible precursor candidates according to the correlation of the chromatographic peak shape profile and other additional filtering criteria (e.g. neutral losses and isotopes). The macro was tested with two families of veterinary drugs, sulfonamides and penicillins, which are known to yield diagnostic product ions when fragmented. Data sets obtained from different food matrices (fish and liver), both at high and low concentration of the target compounds, were investigated in order to evaluate the capabilities and limitations of the reported approach. Finally, other possible applications of this technique, such as the elucidation of elemental compositions based on product ions and corresponding neutral losses, were also presented and discussed. © 2013 Elsevier B.V. Source


Kaufmann A.,Official Food Control Authority | Widmer M.,Official Food Control Authority
Analytica Chimica Acta | Year: 2013

A quantitative LC-MS/MS method was developed for the determination of five polypeptide antibiotics (bacitracin, colistin A, colistin B, polymyxin B1 and polymyxin B2) in a variety of food matrices (muscle, liver, kidney, egg and milk). The described method is sufficiently sensitive, selective and provides acceptable recoveries for all compounds. The extraction is based on acidified methanolic solvent. This is followed by a reversed phase solid phase extraction step to clean-up and concentrate the extracts. The use of a modern core shell column in combination with an eluent consisting of trifluoroacetic acid, formic acid and acetonitrile provides chromatographically well resolved analyte peaks The single-step clean-up is fast and produces a sufficiently clean extract in order to control matrix-related signal suppression in the electrospray interface. © 2013 Elsevier B.V. Source

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