A method for the determination of 12 synthetic food dyes (Amaranth, Erythrosine, Allura Red AC, New Coccine, Phloxine, Rose Bengal, Acid Red, Tartrazine, Sunset Yellow FCF, Fast Green FCF, Brilliant Blue FCF, Indigo Carmine) in food was developed using capillary electrophoresis (CE) with photodiode array detection.The dyes were extracted with water and 0.5 ammonia-ethanol (1 : 1) mixture, and cleaned up using solid-phase extraction (Sep-Pak Plus tC18). The dyes were eluted with methanol from the cartridge. The dyes were separated by CE on a bubble cell fused-silica capillary (72 cm to the detector, 75 mm i.d.) using 20 acetonitrile in a mixture of 10 mmol/L potassium phosphate, monobasic and 5 mmol/L sodium carbonate (pH 10.0) as the running bu#er. Identifications of the dyes were performed on the basis of the migration time and the absorbance spectrum of each peak. The coe$cients of variation of the migration times and the peak areas were 0.28ῌ0.62 and 1.84ῌ 4.30, respectively (n5). The identification limits using the absorbance spectra of the dyes were 10 mg/mL for Brilliant Blue FCF and Fast Green FCF, and 5 mg/mL for the other 10 dyes. The recoveries of the 12 dyes from pickles, soft drinks and candies at the level of 10 mg/g were 70.0ῌ 101.5. The method was applied to the analysis of dyes in foods. The dyes detected by CE were in agreement with those detected by paper chromatography.
An HPLC method with fluorescence detection was developed for the determination of propyl gallate, nordihydroguaiaretic acid, butylated hydroxyanisole (2-and 3-tert-butyl-4-hydroxyanisole), tert-butylhydroquinone and octyl gallate in edible oils and foods.The antioxidants in edible oil were isolated directly with acetonitrile saturated with n-hexane. The antioxidants in food were extracted with ethyl acetate and the extract was concentrated under vacuum. They were isolated from the residue with acetonitrile saturated with n-hexane. The acetonitrile layer was centrifuged at 5,000 rpm for 10 min. The HPLC separation was performed on a Symmetry C18 column (3.5 mm, 4.6 mm i.d.150 mm) using a mixture of 5 acetic acidῌacetonitrileῌmethanol (4 : 3 : 3, v/v/v) as the mobile phase and monitored by using a fluorescence detector with time programming. Sample peaks were identified by comparison of the fluorescence spectra with those of antioxidant standards. Average recoveries of fortified antioxidants at 100 mg/g were 72.1ῑ99.6. Coe$cients of variation were 0.7ῑ7.2.
Azodicarbonamide ADA is used in some countries as a flour bleaching agent and a dough conditioner. However, ADA is prohibited for use as a food additive in Japan. Therefore, it is necessary to establish an efficient and sensitive method to determine ADA in wheat flour. A simple and practical procedure to analyze ADA in wheat flour and prepared flour mixes was developed. ADA was extracted from samples by ultrasonication with acetone. ADA in the solution was derivatized with triphenylphosphine TPP . The ADA-TPP derivative was concentrated and cleaned up using a reversed-phase solid-phase extraction cartridge, and the ADA-TPP derivative was analyzed using HPLC for determination and LC-MS/MS for identification. Good linearity was achieved over the concentration range of 0.25-100 ppm ADA in wheat flour and prepared flour mixes. The mean recoveries from wheat flour and prepared flour mixes fortified at the levels of 1 and 10 ppm ranged from 86.9 to 101.0 , and the coefficients of variation ranged from 1.9 to 3.4 .
A rapid coulometric method was developed for the measurement of peroxide value In edible oils and fats. The sample size and reagents volumes In this method are considerably less than those in the American Oil Chemists' Society method. Iodine produced by the reaction of the Iodide Ion and peroxide In the sample Is electrochemlcally reduced at the carbon-felt electrode more rapidly than it is with lodometric titration. The present method Is successfully applied to the measurements of edible oils and fats, and the coulometric results obtained are consistent with those obtained by iodometry.
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