Abstract: A method for quantitative analysis of imidazolidinyl urea in cosmetics based upon determination of amount of formaldehyde released from imidazolidinyl urea was established.Formaldehyde was released by the action of Nash's reagent on imidazolidinyl urea under a certain constant temperature.Amount of formaldehyde released at different time was measured via spectrophotometric method and can be used for the quantitative analysis of imidazolidinyl urea.Results showed that,under 60 ℃ for 1 h,release of the formaldehyde from imidazolidinyl urea can achieve a stable state and completed.1 mol of imidazolidinyl urea can release 1.116 mol of formaldehyde.The lowest limit of detection is 0.2 mg·L^-1 and the spiked recoveries of the method range within 75%-98%.

Key words: cosmetics, imidazolidinyl urea, formaldehyde, spectrophotometric method, Nash's reagent