Determination of tartaric acid in wines by FIA with tubular tartrate-selective electrodes

A flow injection analysis (FIA) system comprising a tartrate- (TAT) selecti ve electrode has been developed for determination of tartaric acid in wines . Several electrodes constructed for this purpose had a PVC membrane with a complex of quaternary ammonium and TAT as anion exchanger, a phenol deriva tive as additive, and a more or less polar mediator solvent. Characterizati on of the electrodes showed behavior was best for membranes with o-nitrophe nyl octyl ether as solvent. On injection of 500 muL into a phosphate buffer carrier (pH = 3.1; ionic strength 10(-2) mol/L) flowing at 3 mL/min, the s lope was 58.06 +/- 0.6 with a lower limit of linear range of 5.0 x 10(-4) m ol/L TAT and R-2 = 0.9989. The interference of several species, e.g. chlori de, bromide, iodide, nitrate, gallic acid, tannin, sucrose, glucose, fructo se, acetate, and citrate, was evaluated in terms of potentiometric selectiv ity coefficients. The Hofmeister series was followed for inorganic species and the most interfering organic ion was citrate. When red and white wines were analyzed and the results compared with those from an independent metho d they were found to be accurate, with relative standard deviations below 5 .0%.