Multisyringe flow system: determination of sulfur dioxide in wines

A multisyringe flow system for the spectrophotomeric determination of sulfur dioxide in wines is described. The methodology is based on the well-known reaction among SO₂, formaldehyde and pararosaniline. The proposed manifold also includes a gas diffusion unit in order to prevent the colour interference of red wines in the spectrophotometric measurement. The proposed method was successfully applied to the determination of free SO₂ (2-75 mg 1^-1) and total SO₂ (10-250 mg l^-1) in wines, just by changing a few operating parameters in the controlling software. A sampling-rate of 25-30 samples per hour was achieved with good repeatability for 10 consecutive injections of wine samples (RSD < 3.2%). The results obtained from 10 wine samples for each determination were statistically comparable to those obtained by the recommended procedure.