Factors affecting polycyclic aromatic hydrocarbon (PAH) concentrations in oils and fats, cereals and related foodstuffs have been investigated. Levels of PAHs were low in retail fish and animal-derived oils and fats, such as butter, where the mean benzo(a)pyrene concentration was 0.06 microgram/kg. Higher and more variable amounts were present in retail vegetable oils for which the mean level of benzo(a)pyrene was 1.29 micrograms/kg. Margarine was the major dietary source of PAHs in the oils and fats total diet group accounting for 70% of the benzo(a)pyrene intake from these commodities. The levels of benzo(a)pyrene were less than 0.1 microgram/kg in white flour and similar amounts were found in bread showing that PAHs are not formed to any significant extent during baking of bread. Higher concentrations of up to 2.2 micrograms/kg benzo(a)pyrene were detected in cereal-derived products containing higher levels of edible oils such as pudding-based desserts, biscuits and cakes. The presence of vegetable oils as an ingredient also appeared to increase PAH levels in infant formulae as the mean benzo(a)pyrene content of 0.49 microgram/kg was four times higher than that found in skimmed milk. The mean value in the feed, after reconstituting the formulae with water, would however have been less than 0.1 microgram/litre. Investigations of rape seed drying showed no increase in any PAHs when cold, or electrically-heated air was used. Combustion gas drying had no effect for the larger PAHs such as benzo(a)pyrene but caused mean increases of between 41% and 126% for fluoranthene, pyrene and chrysene. These increases did not correlate with reductions in moisture content of the rape seed implying that the combustion conditions were more important to PAH contamination than the degree of exposure to combustion gases. Concentrations of these three PAHs and also benz(a)anthracene were all significantly reduced by up to a factor of five when crude oils were refined suggesting that carefully controlled direct drying need not contribute PAHs to refined oils and fats.
An analytical procedure has been developed for the determination of trace amounts of ethyl carbamate in fermented foodstuffs and alcoholic beverages. Concentrations were generally below the 1-5 micrograms/kg detection limit in bread, cheese, yoghurt, beer, gin and vodka. Higher concentrations were found in the other alcoholic beverages examined, which included whisky, fruit brandy, liqueur, wine, sherry and port.
Background 1,25-Dihydroxy vitamin D3 (DHVD) is the active metabolite of vitamin D, required to maintain blood calcium concentrations. Measurement has proved challenging as it circulates in picomolar concentrations and must be differentiated from other dihydroxyvitamin D species. Clinically, it is essential to be able to determine the cause of hypercalcaemia, which may be due to DHVD excess. Methods The liquid chromatography-mass spectrometry (LCMS) assay which has been developed uses immunoextraction of 0.5 mL serum followed by Amplifex™ derivatization of the dried eluent, with the analysis using the SCIEX 6500+ instrument taking a run time of 11 min. Results The limit of quantitation was determined (15 pmol/L) and the method is linear up to at least 600 pmol/L. Repeatability ranged from 6.1% at 23 pmol/L to 2.5% at 172 pmol/L and intermediate imprecision was 15.6% at 26 pmol/L to 8.3% at 173 pmol/L. The method is unaffected by icterus, haemolysis or lipaemia. Good performance was achieved with the samples from the vitamin D external quality assessment scheme, demonstrating a negative bias compared with the all lab trimmed mean (average –13.8%) and the specific method group (average –7.75%). A negative bias was observed across the concentration range found in 78 patient samples in comparison to a commercial radioimmunoassay (mean –47.8%). This was not unexpected and is likely due to better specificity of the mass spectrometry assay and the lack of a commutable standard reference calibrator. Conclusions We have developed a sensitive and robust LCMS method for the analysis of DHVD in serum, utilizing immunoextraction and derivatization to provide specificity.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.