Determination of ascorbic acid in its mixtures with thiols by reversed- phase high-performance liquid chromatography with electrochemical detection using a DC-TAST polarograph

Determination of ascorbic acid and isoascorbic acid by capillary zone electrophoresis: application to fruit juices and to a pharmaceutical formulation

Capillary zone electrophoresis was applied to the determination of ascorbic and isoascorbic acid, analysing the various parameters of influence such as the separation voltage, the buffer pH and concentration, the type of separation capillary or the loading conditions. Both analytes could be adequately determined within 5 min. The proposed method uses a 20 cm x 25 microns i.d. coated column, 0.1 M phosphate buffer pH 5.0, 8 kV separation voltage and light absorption detection at 265 nm. Linear calibration curves were obtained in the 0-1 mg mi-1 range, with detection limits of 0.5 micrograms ml-1. This method proved to be very rapid, simple and practical for the qualitative and quantitative determination of ascorbic acid in lemon and orange juices, as well as in a commercially available pharmaceutical formulation.

Simultaneous determination of ascorbic acid and dehydroascorbic acid in cultures of C3H/10T1/2 cells

A reproducible method is described for the separation and quantification of ascorbic acid and dehydroascorbic acid by ion-pairing reverse-phase high performance liquid chromatography and detection by absorbance at 232 nm. Lowest detectable concentrations with a linear response of detection were 5 nmol for ascorbic acid and 50 nmol for dehydroascorbic acid. This method was applied to the analysis of C3H/10T1/2 cells and culture medium after influx or efflux experiments and single or multiple treatments with ascorbic acid. Subsequent measurement of the radioactivity in the eluted fractions increased the detectability of both ascorbic acid and dehydroascorbic acid to 10 to 20 pmol.

Determination of ascorbic acid in beers by high-performance liquid chromatography with electrochemical detection

A reversed-phase high-performance liquid chromatographic method with electrochemical detection was developed for the determination of ascorbic acid in beers at the nanogram level. The column was packed with C18 bonded silica, commercially available or prepared in the laboratory. The eluent was a citrate buffer solution with an ion-pairing reagent. Several fatty amines were tested as such reagents. Good recoveries indicated that no interfering substances were eluted together with ascorbic acid. The main advantages are the rapid and simple preparation of the samples and the specificity and sensitivity of the detector, which are superior to those of any other detection systems proposed for the determination of ascorbic acid in beers.