Sequential determination of carbon dioxide and free sulfur dioxide in wineby flow-injection pervaporation with in series potentiometric-photometric detection

A method for the simultaneous determination of CO2 and free SO2 in wines ba sed on the use of a continuous arrangement coupled to both a pervaporator a nd in series arranged potentiometric and photometric detectors is proposed. After pervaporation, both analytes give one common potentiometric signal a nd then the free SO2 is photometrically determined via the colored compound formed with p-rosaniline and formaldehyde. The CO2 content is determined b y difference. The range of the method is linear between 2.0 and 20.0 mg/L f or free SO2 and 50.0 and 600.0 mg/L for CO2, with a precision, expressed as relative standard deviation, of 7% in both cases. The method was applied t o different Spanish wines and the results compare well with those obtained by the corresponding official methods.