Ingredients prohibited for use in cosmetics are listed in the Cosmetics Standards (Ministry of Health and Welfare Notification No. 331, September 2000). Formaldehyde is one ingredient regulated by the standard. Analysis was performed according to the cosmetic test HPLC method. Formaldehyde in a test solution was separated using an ODS-3 column, then derivatized by reaction with acetylacetone solution to yield 3,5-diacetyl-1,4-dihydroltidine, which was then measured using a UV-visible detector.
This post-column method allows selective analysis with little or no influence from contaminants.