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PubMedDate not supplied

Liquid chromatographic analysis of dehydroacetic acid and its application to wines.

A simple liquid chromatographic procedure is described for determination of the preservative dehydroacetic acid (DHA) in wine. No cleanup procedure is necessary; the sample is injected onto an NH2 column without further pretreatment. The mobile phase is a 9 + 1 mixture of acetonitrile-sodium acetate buffer adjusted to pH 4 with acetic acid. Total run time is less than 10 min. Dehydroacetic acid is determined by using the absorbance at 307 nm; the detection limit is estimated to be 0.2 ppm. The method may also be suitable for detecting DHA in a variety of foodstuffs in low concentrations.

Chromatography, Liquid↗
PubMed2006

Kinetics of the substitution of dehydroacetic acid in tris (dehydroacetato) Fe(III) complex by 8-hydroxyquinoline, di- and tetra-hydroxyquinone.

The ligand substitution reactions of dehydroacetic acid (Hdha) in [Fe(dha)(3)] with second ligand such as 8-hydroxyquinoline (Hquin), 1,4-dihydroxyanthraquinone (H(2)dhaq) and 1,4,5,8-tetra-hydroxyanthraquinone (H(4)thaq) were investigated spectrophotometrically by in low polarity solvents like benzene, chloroform and dichloromethane. It is deduced that the substitution reaction takes place through one successive step. The reaction was performed at four different temperatures (5-25) degrees C, and it exhibits a first order dependence on the concentration of the starting complex. The observed rate constant depends on the concentration of both leaving and entering ligands. The evaluation of the kinetic data gives activation parameters which support an associative mechanism in the transition states and the higher rate of substitution of the dha in Fe(dha)(3) complex is due to entropy effect. The solid complexes were synthesized and characterized by elemental analysis, IR and UV-vis spectral techniques.

Anthraquinones↗
PubMed1983

Gas-liquid chromatographic determination of dehydroacetic acid in squash and wine.

A gas-liquid chromatographic procedure has been developed for the determination of the preservative dehydroacetic acid (DHA) in frozen cut squash and white wine. The cleanup procedure uses the acidic character of DHA to enhance separation from interfering substances. Recoveries were 93-104% from squash fortified at 30, 65, and 130 ppm and 96-99% from wine fortified at 50, 100, and 200 ppm. The method can be used to establish that the amount of DHA used in squash does not exceed the permissible level of 65 ppm.

Chromatography, Gas↗
PubMed2002

Simultaneous analysis of dehydroacetic acid, benzoic acid, sorbic acid and salicylic acid in cosmetic products by solid-phase extraction and high-performance liquid chromatography.

A high-performance liquid chromatographic (HPLC) method for simultaneous determination of dehydroacetic acid (DHA), benzoic acid (BA), sorbic acid (SOA) and salicylic acid (SA) was developed for application to cosmetic products. Isocratic reversed-phase HPLC was employed for quantitative analysis using tetra-n-butylammonium (TBA) hydroxide as an ion-pair reagent. Cosmetic samples were purified by solid-phase extraction using Bond-Elut SI cartridges. Four acidic preservatives were eluted with methanol from cartridges. The HPLC assay was carried out using TSK gel ODS-80TM column (5 microm, 150 x 4.6 mm I.D.). The mobile phase consisted of a mixture of water and methanol (65:35, v/v) containing 2.5 mM TBA hydroxide adjusted with phosphoric acid to pH 7.0. The calibration curves of these preservatives showed good linearity with UV detection (235 nm). The correlation coefficients were better than 0.999 in all cases. The lower limits of detection (defined as a signal-to-noise ratio of about 3) were approximately 2.5 ng for DHA, 4.0 ng for BA, 2.0 ng for SOA and 5.5 ng for SA. The procedure described here is simple, selective and is suitable for quality control of finished cosmetic products.

Benzoic Acid↗