PREPRINTS OF THE 1997 ANNUAL SCIENTIFIC SEMINAR 57 GEL PERMEATION CHROMATOGRAPHY: AN EFFECTIVE METHOD OF QUANTIFYING THE ADSORPTION OF CATIONIC-POLYMERS BY BLEACHED HAIR Beatriz Blanco, Barbara A. Durost, Ronald R. Myers Calgon Corporation, Pittsburgh PA 15230 INTRODUCTION Gel Permeation Chromatography (GPC) has been validated and proved to be an effective, reproducible, simple and quick method to measure the substantivity of cationic polymers on hair from aqueous solutions. The uptake of eight cationic conditioning polymers on bleached hair was measured indirectly by determining the difference in polymer concentration in the solutions before and after the treatment of the hair. A previously published result for the uptake on very damaged bleached blond hair of polyquaternium 7, measured by radiolabeling using 14C, correlates with the result obtained by GPC. EXPERIMENTAL Conditions Type of hair: Polymers tested: Treatment solutions: bleached blond hair from DeMeo Brothers. polyquaterniums 4, 6, 7, 10, 11, 22, 28 and 39. 0.10% polymer solids aqueous solutions pH= 6.0+ 0.1. Solutions were made with deionized water. 22øC Temperature: Sample Preparation 2.30 g of thoroughly washed • hair were allowed to soak in 150.0 g of treatment solution for 30 minutes. A reciprocating mixer with a speed of 420 min 4 was used to agitate the samples. At the end of the treatment time, the hair was squeezed with a pair of tweezers and removed from the treatment solution. The remaining solutions were called post-treatment solutions. The hair was then rinsed three times with 50.0 ml of distilled water each time. Untreated treatment solutions (without hair) were subjected to the same conditions. All experiments were performed in triplicate. Sample Analysis The treatment solutions, rinses, post-treatment solutions and untreated treatment solutions were analyzed using the following equipment: Instrument: Water's GPC Detectors: Water's 410 RI, Wyatt MALLS Column: TSK PW3000 Eluent: 0.15M Na2SO 4 + 1% Acetic Acid, pH 3.3 Flow: 1.0ml/min, Temp: 25øC, Vol: 200/zL Two injections of each treatment solutions were made. Based upon the polymer mass injected and the RI polymer peak area the specific refractive index (dn/dc) of each sample was computed. These two dn/dc values were averaged. Two injections of each post-treatment solution were made. The mass of polymer injected was then determined based upon the RI polymer peak area and the dn/dc measured from the treatment solution. The same procedure was used to compute the mass of polymer in each rinse. The average of the three polymer mass determinations for each experiment was obtained. The amount of polymer found in the rinses was negligible. The calculated difference in the amount of cationic conditioning polymer present in the treatment and post-treatment solutions represents the cationic polymer uptake by the hair sample. No shear degradation of polymer was observed in the untreated treatment solutions. The precision study of this test method showed that at the 99% confidence level (3 sigma) the confidence range was 3 %. The error of the method was 1.8 % A t test was used to determine whether the measured polymer mass in the treatment and post-treatment solutions were statistically different. The substantivity of two lots of polyquaternium 39 was determined by two analysts on separate occasions. Both analysts obtained the same substantivity value for this polymer. This result demonstrates that the method is reproducible. Results and Discussion The graph below depicts the substantivity values obtained for the different polymers.

58 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS There seems to be no direct correlation between the substantivity of the polymers under the tested conditions and their molecular weight or cationic charge density. These two latter factors, plus the ability of the polymer to form hydrogen bonding and the Wan de Waals attraction forces with the hair seem to work together to provide polymer substantivity on hair. In the past, the substantivity of polyquaternium 7 was determined on very damaged bleached blond hair at 22øC and an exposure time of 30 minutes using •4C tagged polymer •. The result obtained using the GPC/RI method under the same set of conditions correlated with the result obtained by tagging the polymer with •4C. Polymer GPC Substantivity •4C Substantivity (/zg polymer/mg of hair) (/zg polymer/mg of hair) Polyquaternium 7 7.0 7.1 It should also be noted that the relative substantivity values obtained for some of the polymers correlate with previously published data •'3. Conclusion Gel Permeation Chromatography proved to be a very effective, reproducible, simple and quick method to measure the substantivity of cationic polymers on hair from aqueous solutions. This method is also much less expensive than •4C radiolabeling and there is no need to take care of radioactive waste disposal. References •Hair washing procedure available upon request. 2A.R. Sykes and P.A. Hammes, The Use of Merquat Polymers in Cosmetics, Drug and Cosmetics Industry, February 1980. 3D.Lutz, G Holtzinger and A. Khaiat, Substantivty of Cationics to the Hair-A New Determination Methodology, Cosmetics and Toiletries Manufacture.