Indirect determination of Fe(III) in synthetic samples and iron dextran tablets by capillary electrophoresis with ultraviolet detection.

A capillary electrophoresis method based on the oxidation of ascorbic acid is proposed for the indirect determination of Fe(III). Fe(III) concentration corresponds to the decrease in ascorbic acid peak area. The calibration graph was linear in the range of 1.68-112 mg/L for Fe(III), which was easily detected at a concentration of 1.12 mg/L at 3 times the standard deviation of the blank divided by the slope of the calibration graph. The lack of interferences from Fe(II) in synthetic samples and 3 excipients (starch, magnesium strearate, and microcrystalline cellulose) in dextran tablets in the determination of Fe(III) confirmed the high selectivity of the proposed method. Its application to the determination of Fe(III) in several synthetic samples and iron dextran tablets produced excellent results.

A quick method for the simultaneous determination of ascorbic acid and sorbic acid in fruit juices by capillary zone electrophoresis.

A method of quickly determining ascorbic acid and sorbic acid by capillary zone electrophoresis with ultraviolet detection was developed. The choice of background electrolyte, wavelength, injection time and applied voltage were discussed. Ascorbic acid and sorbic acid were well separated in 80mmolL(-1) boric acid-5mmolL(-1)borax (pH = 8.0) in 5min at the detecting wavelength of 270nm. Under the optimum condition, the method has linear ranges of 2.54-352.00mgL(-1) for ascorbic acid and 1.08-336.39mgL(-1) for sorbic acid with the detection limit of 1.70mgL(-1) for ascorbic acid and 0.54mgL(-1) for sorbic acid, respectively. Other organic acids in fruit juices have no effect on the detection. This method is very feasible and simple and can be used to detect ascorbic acid and sorbic acid in fruit juices.