A sensitive flow analysis system for the fluorimetric determination of low levels of formaldehyde in alcoholic beverages

A sensitive FIA method was developed for the selective determination of formaldehyde in alcoholic beverages. This method is based on the reaction of Fluoral-P (4-amine-3-pentene-2-one) with formaldehyde, leading to the formation of 3,5-diacetyl-1,4-dihydrolutidine (DDL), which fluoresces at λex = 410 nm and λem = 510 nm. The analytical parameters were optimized by the response surface method using the Box–Behnken design. The proposed flow injection system allowed for the determination of up to 3.33 × 10−5 mol L−1 of formaldehyde with R.S.D. < 2.5% and a detection limit of 3.1 ng mL−1. The method was successfully applied to determine formaldehyde in alcoholic beverages, without requiring any sample pretreatment, and the results agreed with the reference at a 95% confidence level by paired t-test. In the optimized condition, the FIA system proved able to analyze up to 60 samples/h.