Construction and use of a tubular picrate ion-selective electrode for reducing sugar determination in Port wine by flow-injection analysis

• Published in: Analytica chimica acta 1995-06, Vol.308 (1), p.122-128
• Main Authors: Lopes, Teresa I.M.S., Rangel, António O.S.S., Lima, JoséL.F.C., Montenegro, M.Conceição B.S.M.
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Fermented food industries; Flow injection; Food industries; Fundamental and applied biological sciences. Psychology; Ion selective electrodes; Picrate; Sugar; Wine; Wines and vinegars
• ISSN: 0003-2670; 1873-4324
• DOI: 10.1016/0003-2670(94)00598-G

A picrate ion-selective electrode without inner reference solution and based on bis(triphenylphosphoranylidene)ammonium picrate dissolved in 2-nitrophenyloctyl ether was constructed and its characteristics assessed. With respect to reducing sugar determination in Port wine, a tubular electrode based on the same sensor system was developed and incorporated into a flow-injection manifold devised for this determination. The methodology involves a reaction between the reducing sugar and picric acid, the decrease in the picrate concentration being monitored with the tubular electrode. A linear dependence between peak width, at a fixed potential and the logarithm of sugar concentration in the range 25–200 g l −1 was obtained. The proposed system allows wine samples to be injected with no previous treatment and allows a sample throughput of 50 determinations per hour, a relative standard deviation less than 4%, and the results are comparable to the reference procedures.