132 JOURNAL OF COSMETIC SCIENCE industry because of their natural ability to bind to the anionic surfaces of hair and skin (2). How this deposition takes place from surfactant-containing systems in which the cationic polymers find themselves in a broth of anionically charged surfactant molecules remains a topic of discussion (3-6). Many shampoo and body wash products available today offer the consumer a blend of both cationic polymers and emulsified silicone oils as a conditioning package. However, little work has been conducted to address the influence that these two macromolecules have on one another when they are delivered simultaneously to the body via the washing process. Recently, we reported on the use of x-ray fluorescence spectroscopy to examine the influence of cationic polysaccharides on silicone oil deposition (7). The technique is unique for this application, as it allows us to examine a keratin surface, i.e., hair, in a non-destructive fashion to determine how a dissolved cationic polymer affects the de- position behavior of dispersed dimethicone. We wish to broaden our discussion to examine the influence that cationic polymer concentration has on silicone deposition. In addition, we will show that the results we have obtained using our model shampoos appear to correlate well with the silicone deposition we find for a commercially available "2-in-l" conditioning shampoo. EXPERIMENTAL The model shampoo formulations and cationic polymers employed in this study are shown in Table I. The testing protocol, shampooing protocol, and other information important to the technique can be found elsewhere (7). This referenced article goes into considerable detail to describe sources of potential error in the use of x-ray fluorescence for direct analysis of silicon on hair. These errors include such experimental details as the method of hair washing, particle size of the emulsified silicone oils, number of x-ray scans, and direction of the hair during scanning, among others. We elected, for this reason, to discuss only average relative silicon deposition without reference to error. Table I Shampoo Formulation and Cationic Polymers Ingredients A B C D E F G Ammonium lauryl sulfate 14.0 14.0 14.0 14.0 14.0 14.0 Ammonium laureth sulfate 3.9 3.9 3.9 3.9 3.9 3.9 Cocamidopropyl-betaine 3.0 3.0 3.0 3.0 3.0 3.0 Ethylene glycol distearate 2.0 2.0 2.0 2.0 2.0 2.0 Dimethicone • 1.5 1.5 1.5 1.5 1.5 -- Cationic polymer 0.5 0.3 0.1 0.5 -- -- Polymer 12 Polymer 1 Polymer 1 Polymer 23 Preservative 0.4 0.4 0.4 0.4 0.4 0.4 Water 74.7 74.9 75.1 74.7 75.2 76.7 15-Pareth-9 100.0 • Dimethicone is a blend of a high-molecular-weight gum, and a low-molecular-weight fluid in the ratio of 60:40. 2 Polymer 1:Polyquaternium-10 of approximate molecular weight 400,000 and approximate percent cationic nitrogen of 1.0. • Polymer 2:Polyquaternium-10 of approximate molecular weight 900,000 and approximate percent cationic nitrogen of 1.0.

SILICONE OIL DEPOSITION ON HAIR 133 Readers who wish to understand the error and sources of error inherent in the technique are directed to the more detailed article. We wish, at this time, to describe in a general fashion how the x-ray fluorescent spectrometer works in our particular application and some of the important sources of error that can affect the measurements. We have employed both a Kevex energy dis- persive instrument and a Philips Electronic P2400 wavelength dispersive instrument. The terms energy dispersive and wavelength diJ•ersive relate to the method of wavelength discrimination, and for those interested in a more thorough description of these terms, we suggest a recent review by Torok et al. (8). The Philips instrument is more modern and is equipped to spin the sample during analysis. We have found that due to the directionality of hair, it is essential to spin the fibers during analysis, but with the Kevex instrument, this rotation can be done manually in 90 ø steps and the results obtained correlate very well with measurements taken on the instrument that rotates the samples during analysis (7). We have found that the greatest source of error in the analysis technique occurs in the preparation of the shampoos and the washing of the tresses, and we have outlined our steps to minimize these sources of error as much as possible (7). Within our discussion, references to differences in relative silicon deposition can be considered statistically significant. Figure 1 shows a schematic representation of the x-ray spectrophotometer. Very simply, the device is a direct excitation mode instrument in which the sample, i.e., the treated tress, is directly excited by the primary radiation from the x-ray tube. The x-rays from the source strike the hair tress, covering a sample size of approximately one inch in diameter. The x-rays cause various atoms to emit excess energy at specific energies to afford fluorescence. This technique measures the signal from the atoms (i.e., silicon), without regard to their attributes inside a compound. The characteristic silicon fluo- rescence occurs at 1.74 KeV, and is called the Ko• band. Ssmple To orAggollimotor Detector Probe Tip,/ " ß . I X-ray Excitation(primary) Characteristic. X-rays .....:_rayTube I ! Figure 1. Schematic of x-ray fluorescent spectrophotometer.