Semiautomatic flow-injection method for determination of volatile acidity in wines

A flow-injection (FI) method based on analytical pervaporation was assessed for its routine use in the determination of volatile acidity in winery lab oratories. The new method was compared with both the official method and th e Mathieu method, which is most often used in Spanish wineries, by testing 30 different wines, including young and aged, and sweet and dry wines from Montilla-Moriles appellation d'origine. The robustness of the new method wa s established, and then all 3 methods were studied in terms of range of lin earity and regression of the calibration curve, repeatability, reproducibil ity, sensitivity, detection and quantitation limits (LOD and LOO, respectiv ely), and time of analysis. The FI method surpassed the Mathieu method in r eproducibility and both the Mathieu and official methods in LOD and LOO and sensitivity; it also required less personnel involvement and shorter analy sis time. The statistical criteria established by the Office International de la Vigne et du Vin were applied to the data and the results obtained ind icated that the differences between the analytical parameters of the 3 meth ods are not significant and can be applied indistinctly. The correlation of the methods was studied by taking them 2 by 2, and the corresponding equat ions, coefficients, and deviations confirmed the statistical results. Thus the new method can be used in winery laboratories with clear advantages ove r its 2 counterparts (the routine and official methods).