DETERMINATION OF DIAZOLIDINYL UREA 179 diazol idinyl urea Figure 4. Electropherogram for hand lotion (5%). Sample preparation and experimental conditions given in text. PRECISION Fit of standard additions curve. The average correlation coefficient (r 2) for the six replicate analyses of the hand lotion was 0.9907 -- 0.0081. For the six replicates of the pain- relieving gel, the average r 2 was 0.9971 q- 0.0019. Elution time. The average elution time of diazolidinyl urea for the twelve runs of the analysis of the burn-relief gel sample was 4.12 min -- 0.023 min (C.V. = 0.57%). The same treatment for the vitamin E/lanolin hand lotion gave an average elution time of 3.97 min q- 0.026 min (C.V. = 0.65%). Peak area. Standard solutions of 0.01, 0.02, and 0.05 % diazolidinyl urea were run three times each. The coefficient of variation for each set of runs was 3%. A 5% solution

180 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Table I Recovery of Diazolidinyl Urea in a Variety of Spiked Matrices Sample Dilution (%) % Added • % Recovery Pain-relief gel Burn-relief gel Vitamin E/lanolin lotion Douche Shampoo 2.5 0.01 82 2.5 0.01 88 5.0 0.005 103 5.0 0.02 91 10 0.025 79 5.0 0.025 79 2.5 0.01 95 5.0 0.005 71 5.0 0.01 80 5.0 0.02 80 2.5 0.025 82 10 0.01 68 10 0.01 78 10 0.005 82 10 0.01 78 10 0.02 74 Concentration of spike not adjusted for dilution of sample. Table II Determination of % Diazolidinyl Urea by the Method of Standard Additions in a Variety of Consumer Products Product % Found • Hand lotion 0.35 (n = 6) Burn-relief gel 0.33 (n = 2) Pain-relieving gel 0.28 (n = 6) Shampoo 0.13 (n = 3) Douche 0.16 (n = 2) Values corrected for sample dilution. of hand lotion was prepared as described and analyzed six times (one vial). The average peak area was 287263 -+ 5458 (C.V. = 1.9%). Six samplings of a 5% solution of hand lotion (six vials) gave an average peak area of 289545 -+ 3475 (C.V. = 1.2%). Diazolidinyl urea found. Six samples of the pain-relieving gel were prepared and ana- lyzed. The average diazolidinyl urea found was 0.28% -+ 0.027% (C.V. - 9.6%). Six samples of vitamin E and lanolin hand lotion were prepared. Analysis gave an average % diazolidinyl urea of 0.35% -+ 0.030% (C.V. = 8.6%). In conclusion, a method has been described for the direct determination of diazolidinyl urea in cosmetic formulations. The method provides rapid elution time of the analyte (•4 minutes) and excellent resolution from other detectable formulation components. Also, there is no need for the derivatization/degradation procedures traditionally used for these analyses. CE is rapidly becoming an accepted analytical technique, and this method should prove useful in the determination of diazolidinyl urea. However, there is a very broad range of matrices and components found in cosmetic products. The