Simultaneous supercritical fluid derivatization and extraction of formaldehyde by the Hantzsch reaction

A study where the Hantzsch reaction is used to produce the chemical derivat ization of formaldehyde in a supercritical medium is presented in this pape r. Pressure, temperature and other parameters such as static and dynamic ex traction time must be optimized to increase the yield of this kinetically c ontrolled reaction. A 2(5-1) (resolution V) factorial design was used to st udy the significant parameters affecting the supercritical process in terms of resolution and sensitivity. A subsequent central composite design was e mployed to find the conditions of maximum response. Ultraviolet-visible spe ctrophotometry was used as the detection technique. The optimum conditions were used for the determination of formaldehyde in real finger-paints by me ans of the previous addition of known quantities of this analyte to the pai nt. Results were compared with those obtained with supercritical fluid extr action and subsequent chemical derivatization and an improvement of sensiti vity as well as a reduction of time of analysis, solvent waste and reagents consumption were observed. (C) 2000 Elsevier Science B.V. All rights reser ved.