Application of mass spectrometry in the regulatory analysis of pesticides and industrial chemicals in food and feed commodities

Confirmation of trace level residues in the food supply

With the recent proliferation of mass spectrometric methods available for the identification and confirmation of various compounds in different environmental matrices, it is timely to address the criteria desirable in a regulatory sample case. The emphasis of this review is on the experimental process of confirmation at concentration levels in the range of low parts per million (ppm) to parts per trillion (ppt). At such levels, various data manipulations or alternate choices of approaching the analytical problem of confirmation must be employed to ensure an acceptable result. The problems experienced when dealing with nanogram levels in analysis are much more complex than when recording a mass spectrum of an ample supply of a reference standard. This review reflects an interpretation of the developing status of confirmation since there does not yet exist "accepted criteria".

Residue characterization of triadimefon in grapes by gas chromatography and mass spectrometry/mass spectrometry

A field study of the use of the new fungicide triadimefon (Bayleton) on grapes has indicated that residue levels of 0.01 ppm may be expected on the ripe fruit in spite of the 60-75 day interval from spray to harvest. Triadimefon and its primary metabolite triadimenol (Baytan) have been characterized by gas chromatography and mass spectrometry to provide identification down to a detection level of 0.001 ppm. Recovery studies on these fungicides have indicated that they are completely extracted by the single multi-residue analytical methodology presently in use for monitoring fresh produce.

Levels of plasticizer in the frequent plasma donor

Di-2-ethylhexyl phthalate (DEHP), a commonly employed plasticizer reported to be carcinogenic in rats and mice, has been confirmed to leach from all plastic component parts of the equipment employed in plasma donation. Resident aqueous solutions of both sodium chloride and sodium citrate were found to contain only trace levels of DEHP (0.03 ppm), while stored plasma samples contained levels at least one order of magnitude higher (0.4 ppm). Since at least 5% of all plasma donations in the Los Angeles area are deemed to be of the high frequency classification, investigation into repeated red blood cell exposure to DEHP was considered imperative. However, there was no difference in the levels of DEHP found in the plasma of the frequent plasma donor (50-60 times per annum) relative to the first-time donor. It is concluded that there is no increased contamination threat to frequent plasma donation from migrating plasticizer via red blood cell exposure, at least during the collection process. Furthermore, there is no more risk to recipients of plasma products from frequent donors than from occasional donors. It would seem that the ambient level of DEHP to be expected in stored frozen plasma products averages no greater than about 0.5 ppm.

Extraction and clean-up of contaminants and toxicants from food for mass spectrometric analysis--a literature review

This report presents a review of the literature on the extraction and clean-up procedures used prior to the analysis, by mass spectrometry, of organic contaminants and toxicants in foods and food-related materials. It includes a brief description of the uses of a mass spectrometer and shows how the mode of operation of the machine can influence the amount of clean-up necessary before a sample is presented for analysis. The review covers a variety of contaminants of different compound types in a wide range of foods and not only discusses sample preparation techniques that have been used for contaminant analysis by mass spectrometry but also considers some that could be used. The most commonly used techniques involve solvent extraction followed by a clean-up using liquid-liquid partition or column chromatography or both, although a number of newer methods being evolved are moving towards the ideal of a single-step extraction and clean-up process.

Chemical ionization mass spectrometry of iprodione and its metabolites

One of the cornerstones of an architectural approach adopted by this laboratory in screening vegetables for pesticides and industrial chemicals is the extensive use of element-selective gas chromatographic detectors followed by gas chromatography/mass spectrometry. In this particular case history, a recently introduced European fungicide, iprodione, was thought to be the first reported incidence in mache imported from France. An analytical protocol involving chemical ionization was devised to confirm this finding as well as search for possible potential metabolites.