Stewart L Reynolds

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The principal colouring components of the natural food colouring material annatto, the 9'-cis- and all-trans- isomers of bixin and norbixin, have been prepared in pure form. A reverse-phase HPLC method utilizing photodiode-array detection has been developed to enable their chromatographic and spectroscopic characterization. One minor component, a(More)
A rapid method, using high-performance liquid chromatography (HPLC)/ atmospheric pressure chemical ionization-mass spectrometry, has been developed for the determination of fenbutatin oxide in tomatoes, cucumbers and bananas. Samples were homogenized with sodium carbonate and ethyl acetate, filtered through sodium sulphate, concentrated and solvent(More)
Criteria are presented by which analytical methods may be judged to have been validated for the determination of pesticide residues. All stages of analysis are addressed, from initial preparation of samples to the production of results, but with a focus on simplicity and cost-effectiveness of the requirements. Criteria are provided for both quantitative and(More)
Pesticide residue levels (36 pesticides and some of their metabolites) were determined in the individual units taken from large samples of apples, bananas, celery, kiwi fruit, oranges, peaches and nectarines, pears, plums, potatoes, and tomatoes. The 65 large samples (generally about 100-110 units, but only 45 units of celery) were purchased at retail or(More)
One hundred and thirty samples comprising bread (64), hamburger buns (33), pittas (16), cakes (9) and Christmas puddings (8) from various retail outlets in the UK, have been analysed for the preservative propionic acid. Only one sample of bread, two samples of hamburger buns and three samples of pitta contained propionic acid in excess of 1000 mg/kg (range(More)
Retail samples of livers from calf (23), ox (18), lamb (17), pig (15), chicken (16) and turkey (1) were analysed to determine levels of vitamin A (all trans-retinol) and to aid assessment of the effects of using vitamin supplemented compound feedingstuffs for livestock. For comparison, 22 liver samples from lambs reared on diets not containing(More)
A method using high-performance liquid chromatography-atmospheric pressure chemical ionisation mass spectrometry (HPLC-APCI-MS) has been developed and validated for the determination of the insecticide diflubenzuron [1-(4-chlorophenyl)-3-(2,6-difluorobenzoyl)urea] in mushrooms. Samples were homogenised with acetone, extracted into(More)
The effects of domestic marmalade-making procedures on residues of imazalil, 2-phenylphenol and thiabendazole in 'sweet' oranges were investigated by comparing residue levels in raw fruit and in marmalades, prepared by heating the oranges with water and sugar for about 4 h in a preserving pan on a gas ring or for about 1 h in a microwave oven. Determination(More)
A brief background is provided of the European national bodies which accredit laboratories to the EN 45001 standard and their mutual recognition through the European Cooperation for Accreditation of Laboratories. Some of the requirements for accreditation of a laboratory, for example, the need to demonstrate traceability of measurements, are selectively(More)