FIA Determinations Based on Separation Processes

A hybrid SIA-FIA spectrophotometric method for the determination of total sulfite in white and red wines has been reported (Tzanavaras et al., 2009). The assay was based on the reaction of sulfite with o-phthalaldehyde (OPA) and ammonium chloride. Upon online alkalization with NaOH, a blue product was formed having an absorption maximum at 630 nm. Sulfite was separated from the wine matrix through an online gas-diffusion process incorporated in the SI manifold, followed by reaction with OPA in the presence of ammonia. The reaction mixture merged online with a continuously flowing of NaOH prior to detection. The SIA-FIA manifold is illustrated in Figure 2.8. 

---