Normal phase-liquid chromatography-tandem mass spectrometry with atmospheric pressure photoionization for the purity assessment of 17β-estradiol.

A normal phase-liquid chromatography-hybrid tandem mass spectrometry (NP-LC-MS/MS) method utilizing atmospheric pressure photoionization (APPI) without dopant has been developed and implemented for the simultaneous determination of several estrogenic steroid hormones. The combination of both NP-LC and APPI-MS/MS tolerates the use of solvents that have the advantages of being self-doping for APPI and, at the same time, inhibit the in situ formation of estrogen dimers as frequently observed for conventional reversed phase (RP)-LC methods. The NP-LC-APPI-MS/MS method has been validated in-house, and its performance characteristics (linearity, repeatability, limits of detection, etc.

Mass balance method for the SI value assignment of the purity of organic compounds.

A mass balance method is described for determining the mass fraction of the main component of a high purity organic material. The resulting assigned value is established to be traceable to the SI and can be determined with a small associated measurement uncertainty. Pure organic materials with values and uncertainties determined in this way are necessary as primary calibrators of reference measurement systems in order to underpin the metrological traceability of routine measurement results.

Simultaneous determination of various cardiac glycosides by liquid chromatography-hybrid mass spectrometry for the purity assessment of the therapeutic monitored drug digoxin.

A high performance liquid chromatography-hybrid tandem mass spectrometry (LC-MS(n)) method utilising electrospray ionisation has been developed and implemented for the simultaneous determination of several cardiac glycosides (CGs) as well as their corresponding aglycones formed by and extracted from herbaceous plants of the genus Digitalis. The method has been validated in-house and its performance characteristics (linearity, repeatability, limits of detection, etc.) were assessed for use in the quantification of CGs and their corresponding aglycones.

Production of a calibrant certified reference material for determination of the estrogenic mycotoxin zearalenone.

Several previous interlaboratory studies in the field of mycotoxin analysis have revealed considerable problems, apparent as high between-laboratory standard deviations, or rather non-comparable and non-traceable results. A major reason is lack of proper calibrants for external calibration. Public awareness of substances that mimic or interfere with the activity of natural hormones (endocrine disrupters) has led to increased interest in mycotoxins with estrogenic potential, e.

Production of certified reference materials for mycotoxins: IRMM's view on the assessment of uncertainties.

Analytical difficulty and the economic importance of controlling mycotoxin levels in food and feed led the Community Bureau of Reference (BCR) to prepare a series of certified reference materials (CRM) for various mycotoxins. Because of the wide acceptance of these CRM and the need to ensure the comparability and traceability of measurements in the future it is necessary to prepare and certify new batches of mycotoxin reference materials (RM). In the following text two different approaches for evaluation of the characterisation uncertainty of CRM will be compared using the certification of aflatoxin M(1) (AfM(1)) in milk powder as an example.