Determination of benzoic and sorbic acids in orange juice by high-performance liquid chromatography

Determination of undecylenic and sorbic acids in cosmetic preparations by high performance liquid chromatography with electrochemical detection

A highly sensitive and selective method for the determination of sorbic (SA) and undecylenic acid (UA) in cosmetic formulations by a high performance liquid chromatography method with electrochemical detection (ECD) is described. The pre-column derivatizations of SA and UA and the internal standard (cyclohexanoic acid (cHA)) were carried out using 1-(2,5-dihydroxyphenyl)-2-bromoethanone (2,5-DBE) as an electroactive labeling reagent previously synthesized in our lab. The resulting electroactive esters were separated by isocratic elution of a 5 micrometer Hypersil CN column with acetonitrile-acetate buffer eluent. The compounds were detected by a porous graphite electrode set at an oxidation potential of +0.45 V. The analytical method developed in this study is suitable for quality control assays of complex cosmetic formulations containing sorbic and/or UA.

Rapid high-performance liquid chromatography method for the analysis of sodium benzoate and potassium sorbate in foods

A rapid and reliable method is presented for the determination of the preservatives sodium benzoate and potassium sorbate in fruit juices, sodas, soy sauce, ketchup, peanut butter, cream cheese, and other foods. The procedure utilizes high-performance liquid chromatography (HPLC) followed by UV diode array detection for identification and quantitation of the two preservatives. Liquid samples were prepared by diluting 1 ml of the sample with 10 ml of an acetonitrile/ammonium acetate buffer solution. Samples of viscous or solid foods were prepared by blending the sample with the same buffer solution in a 1:5 ratio followed by a dilution identical to liquid samples. All samples were filtered to remove particulate matter prior to analysis. The HPLC determination of the preservatives was performed using a reversed-phase C18 column and UV detection at 225 nm for sodium benzoate and 255 nm potassium sorbate. The percentage of preservative in the sample was calculated by external standard using authentic sodium benzoate and potassium sorbate. Apple juice, apple sauce, soy sauce, and peanut butter, spiked at 0.10 and 0.050% for both sodium benzoate and potassium sorbate, yielded recoveries ranging from 82 to 96%. The method can detect 0.0010% (10 mg/l) of either preservative in a juice matrix.

Determination of sorbic acid in margarine and butter by high-performance liquid chromatography with fluorescence detection

A procedure is reported for the separation and determination of sorbic acid, as a derivative of 4-bromoethyl-6,7-dimethoxycoumarin, by reversed-phase high-performance liquid chromatography with fluorescence detection using enanthic acid as an internal standard. Sorbic acid, separated from samples of commercial margarine and butter by steam distillation, was evaluated using the proposed procedure and by UV absorption and visible spectrophotometric methods (AOAC). The preparation of the calibration graph and the determination of sorbic acid with the visible spectrophotometric method was improved. The sorbic acid content determined using UV and visible spectrophotometric methods was higher than that obtained with the reversed-phase performance liquid chromatographic method owing to the presence of interfering substances in the samples. The range of recovery and the precision of the proposed method and the reference methods are also reported.

Studies on the analysis of food additives by high-performance liquid chromatography. V. Simultaneous determination of preservatives and saccharin in foods by ion-pair chromatography

A high-performance liquid chromatographic method for the simultaneous determination of sorbic acid, benzoic acid, p-hydroxybenzoic acid and its methyl, ethyl, isopropyl, n-propyl, isobutyl, n-butyl esters and saccharin in foodstuffs is described. For good separations of these compounds, acetonitrile-water-0.2 M phosphate buffer pH 3.6 (7:12:1) containing 2 mM cetyltrimethylammonium bromide as an ion-pair reagent and a Nucleosil 5C18 column are required. A steam distillation method and a Sep-Pak C18 cartridge method for the sample preparation are compared. The recoveries from a coffee drink were generally better than 93.8% and the relative standard deviations were 0.85-2.15% for the Sep-Pak C18 cartridge method.