A strip test based on immobilised Prussian blue (PB) onto modified polyvinyl alcohol (PVA) membrane has been developed for simple determination of ascorbic acid (AA) in beverage samples. The PVA as a solid support matrix has been modified using hydrogen sulphate in order make the membrane harder, elastics and easily handled as a disposable strip. The strip can be accommodated easily inside the cuvette test. The AA as a reductant converts the PB membrane to Prussian white (PW) form, and the attendant of colour change is used for sensing. The colour change of the membrane is spectrophotometrically detected at 716 nm. The strip test has been successfully used for determination of AA in simple and complex beverage. The method is free from interference caused by various ions and active ingredients commonly found in beverages (fruit drinks & juices). The strip test is useful for spectrophotometric analysis of intensively coloured and turbid samples. The results of AA analysis are compared to those obtained using iodometric method. The strip test method could also be used for determination of AA in pharmaceutical samples and medicines.
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