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Abstract
A comparison has been made on the selectivity, accuracy and precision of spectrophotometric, conductometric and potentiometric methods for the determination of ascorbic acid in water which is based on the reduction of gold(III) ion by ascorbic acid. Gold(III) ion forms a complex with gelatin in alkaline medium which on reduction with ascorbic acid produces coloured gold sol. The sol shows an absorption maximum at 540 nm with molar absorptivity of 2.3×10−3litre mol−1 cm−1 and the Sandell's sensitivity of 7.6 × 10−2 μgcm−2. The relative standard deviation is 0.22% and the confidence limit (20 determinations, 95%) is 2.0 ± 0.009%. To examine the extent of sensitivity of the spectrophotometric method the proposed method is compared with the sensitivities of the conductometric and potentiometric methods.