R.M. Marcé

Determination of carboxylic acids, sugars, glycerol and ethanol in wine and grape must by ion-exchange high-performance liquid chromatography with refractive index detection

Method to determine the major carboxylic acids, sugars, glycerol and ethanol in wine and grape must was developed using an ion-exchange column and refractive index detector. A solid-phase extraction method with a strong anion exchanger was used to determine these compounds in sweet wines and in grape musts. With this method it is possible to determine malic acid in sweet wines and in grape musts without interference from sugars. This high-performance liquid chromatographic method was compared with standard methods of analysis. There was good agreement in the accuracy and precision of the compared methods.

An optimized direct method for the determination of carboxylic acids in beverages by HPLC

SummaryA direct method for the simultaneous determination of tartaric, malic, lactic, acetic, citric, shikimic, fumaric and succinic acids in fruit juices and wines by isocratic reversed phase HPLC is reported.The variables (pH, ionic strength, flow and temperature) have been optimized by a modification of the original simplex method. The separation factor (s) and calibrated resolution product (r*) have been used as criteria for selectivity optimization. After validation, the method has been applied to the determination of carboxylic acids in apple, orange and lemon juices, white and red wines and musts during the fermenation process.

A method for the determination of histamine in wine by HPLC with precolumn derivatization with phenylisothiocyanate

SummaryA method for determining histamine in wine by precolumn derivatization with PITC (phenylisothiocyanate) with reversed-phase HPLC and UV detection is reported. Histamine can be determined together with the 24 amino acids within 40 min, or separately in a shorter time (less than 4 min) if a prior solid phase extraction clean-up is used.

Optimization of an ion-exchange high-performance liquid chromatographic method for the determination of carboxylic acids, sugars, glycerol and ethanol in wines

Abstract Optimization of ion-exchange high-performance liquid chromatography with refractive index detection of major carboxylic acids, sugars, glycerol and ethanol in wines was carried out by using a super-modified simplex method and a modelling response surface method. A modification of the CRF criterion (chromatographic response function) for selectivity optimization was used, including different weighting factors for each pair of peaks (VCP criterion; variable coefficient parameters).

Determination of free amino acids by precolumn derivatization with phenylisothiocyanate. Application to wine samples

SummaryA method to determine free amino acids by pre-column derivatization with phenylisothiocyanate is discussed. The method has been applied to determine free amino acids in wine samples, and the results have been compared with those obtained by means of an automatic orthophthal-aldehyde-9-fluorenylmethyloroformate (OPA-FMOC) method.

Optimized isocratic separation of major carboxylic acids in wine

Abstract The reversed-phase high-performance liquid chromatographic separation of major carboxylic acids in wine was optimized. The separation was carried out by isocratic elution, and the optimization of the mobile phase composition with a constant solvent strength was studied. The optimization was carried out by using the overlapping resolution mapping approach employing previously developed software. The best mobile phase consisted of tetrahydrofuran, methanol and acetonitrile as organic modifiers and water as a carrier solvent to maintain a constant solvent strength.

Optimization of the derivatization method for the liquid-chromatographic determination of carboxylic acids in wines

Abstract Several reagents and experimental conditions were tested to optimize the yield of the derivatization procedure for determining carboxylic acids in wines. Two techniques were applied for optimization: a modified sequential simplex method and a simultaneous modelling method. The results obtained were similar; advantages of the latter method are discussed. The optimized conditions (phenacyl bromide as reagent with 18-crown-6 as catalyst with a reaction time of 90 min at 90 ° C) were used to determine the main carboxylic acids in several varietal wines of the Tarragona region.

A sensitive kinetic-thermometric method for Co(II) determination based on the tiron-hydrogen peroxide reaction

Abstract A new kinetic-thermometric method for Co(II) determination at ppb levels has been developed based on its catalytic effect on the tiron-hydrogen peroxide reaction in basic media. The different reaction rates have been measured by means of the temperature-time curves. The application range lies between 3 and 120 ppb and the r.s.d. is 2.1% for 8 ppb of Co(II). Only Ni(II) (⩾ 3 ppm) and Mn(II) (⩾ 80 ppb) interfere. The proposed method has been applied to determine cyanocobalamine (vitamin B12) in a collyrium.

Determination of additives in wine by high-performance liquid chromatography

Abstract Two methods for determining additives in wine samples by reversed-phase high-performance liquid chromatography using UV- visible detection were studied. One method used gradient elution for the separation of the different additives in a short time (less than 12 min). Before the injection of the sample, a solid-phase extraction was applied to obtain better results when a red wine was analysed. The other method effected the separation of these compounds by isocratic elution using cetyltrimethylammonium bromide (CTAB) as an ion-pair reagent, without sample pretreatment.

Optimizing the liquid chromatographic separation of major carboxylic acids in wine by a modelling surface response method

Abstract The separation and determination of the major carboxylic acids in wine by liquid chromatography were optimized by using the modelling surface response method. The chromatographic response function was used as a criterion to obtain an optimum peak separation with the minimum analysis time accepted. The starting mobile phase composition (% methanol) and the change in the solvent strength of the mobile phase during the analysis time were considered as experimental parameters. Malic, tartaric, acetic, lactic, succinic and citric acid were determined by linear gradient elution of their phenacyl bromide derivatives. The optimized method was applied to a red wine sample.