Improved Analytical Method for Free Formaldehyde in Adhesive of Water-Soluble Phenol-Formaldehyde Resin

An improved analytical method(acetylacetone spectrophotometry) for the determination of free formaldehyde in adhesive of water-soluble phenol-formaldehyde resin was established.The influencing factors were studied and the testing conditions were determined.The sample solutions used in this method were prepared by adding buffer solution of acetic acid-ammonium acetate and filtrating.The interferences from resin and sample color were eliminated.Good recoveries from 97.7% to 99.3% were obtained.They were higher than the ones obtained by traditional straight-run distillation process,which were 91.1%.The relative standard deviations obtained by this method were lower than 2.1%.This research discovered that the sample solution and the formaldehyde standard solution were stable when the buffer solution was added.The formaldehyde determination with this analytical method wasn′t disturbed by the phenol when its concentration was 2 000 times as high as the formaldehyde.Compared with chemical titrimetric methods,this analytical method has many advantages such as low detection limit,reagent and sample usages in small amount,high accuracy when the formaldehyde content in the sample is low.It was suitable for the determination of free formaldehyde in water-soluble phenol-formaldehyde resin.