A method for quantification of formaldehyde in the presence of formaldehyde donors in skin-care products.

Reliable and uncomplicated methods for detection of free formaldehyde in products preserved with formaldehyde donors are desirable to decrease the risk of allergic contact dermatitis. The aim of this study was to develop a method that could be used in clinics and workplaces for quantification of free formaldehyde in products preserved with formaldehyde donors. The method developed is named the closed container diffusion (CCD) method. Formaldehyde in a sample is allowed to evaporate in a closed container and react with 2,4-dinitrophenylhydrazine coated on a glass fibre filter. The hydrazone formed is analyzed with HPLC. The method was tested on 3 different formaldehyde donors, imidazolidinyl urea, diazolidinyl urea and 2-bromo-2-nitropropane-1,3-diol, using 4 different cream bases. The results obtained with this method accord, with those obtained with the official method within the European Union (EU). The method is sensitive enough for analysis of patients' products and for control of labelled amounts of formaldehyde in technical products without solvent extraction. As a result of our studies, we observed a risk of exceeding the labelling limit for free formaldehyde in cosmetic products when using the highest amount of diazolidinyl urea allowed within the EU.