Determination of formaldehyde in liquid, solid and semisolid pharmaceuticals and cosmetics by flow injection-pervaporation.

A spectrophotometric method is proposed for the determination of formaldehyde in liquid, solid and semisolid cosmetic and pharmaceutical samples, employing, for the first time in this field, the coupling of a continuous flow configuration to a pervaporation unit. The method is based on the reaction of the analyte with pararosaniline in acidic medium and subsequent formation of a coloured product (alkylsulfonic acid chromophore) with sodium sulfite, which was monitored spectrophotometrically. The method was applied to samples in which the formaldehyde content is regulated by law.