218 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Table IV Comparison of Results for All Samples Analyzed [FTIR Quantitation vs. Sodium Dodecyl Sulfate (SDS) Standard] RM = Raw material FP = Finished product shampoo containing the indicated raw material Titration Sample Analyst # 1 Analyst #2 FTIR Sodium lauryl sulfate RM FP with sodium lauryl sulfate Ammonium lauryl sulfate RM FP with ammonium lauryl sulfate Sodium lauryl ether sulfate RM FP with sodium lauryl ether sulfate Sodium lauryl diether sulfate Alpha olefin sulfonate RM FP with alpha olefin sulfonate 29.3 12.58 13.69 12.21 13.68 28.0 6.9 7.0 24.65 11.44 14.94 14.84 -- 41.0 12.00 12.31 12.65 13.15 28.00 28.03 13.18 13.16 12.91 28.26 27.68 7.0 8.02 24.91 21.23 21.05 14.35 14.26 24.80 21.10 2O.96 39.O8 37.64 12.37 13.49 the same degree of matrix interference in both sample and standard, thereby effectively cancelling out any effects. The "assayed-sample standard" raw materials were carefully assayed using the mixed indicator titration method and these results were taken as the standard values. One sample of each anionic raw material was then quantitated versus the corresponding "assayed-sample standard" by FTIR the results are presented in Table V along with the analogous titration method assays. In this case, the FTIR results show good agree- ment with the titration assays. Also, as expected, the results show that there is no need to use any type of FTIR subtraction since both the "standard" and the sample contain essentially the same concentration of active and matrix. The same experiment was performed with a finished product containing SLES-lEO. This time four samples were quantitated against the "assayed-sample standard" finished product. The results (Table VI) show excellent agreement between FTIR and titration method assay values. The method of quantitation proposed here is simple, accurate, and precise. A sample is poured directly into the CIRCLE without prior treatment of any type. The total analysis time takes about 2.5 minutes. The cell must be cleaned after each analysis however, this is easily accomplished with running water followed by a rinse with acetone and brief air-drying. It should also be noted that while one sample is being scanned into an instrument file, previously acquired sample file information may be plotted and calculations performed.

ANIONIC SURFACTANT QUANTITATION BY FTIR 219 Table V Unknown Raw Material Samples vs. Corresponding "Assayed-Sample Standard" Raw Materials FTIR Using Using Solvent- Titration Unsubtracted Subtracted Sample Abs Value Abs Value Analyst # 1 Analyst #2 Sodium lauryl sulfate Ammonium lauryl sulfate Alpha olefin sulfonate Sodium laury! ether su!fate Sodium lauryl diether su!fate 28.08 27.96 28.00 29.3 28.08 27.94 27.73 27.76 28.26 28.0 27.80 27.86 38.37 38.54 39.08 41.0 38.19 38.30 24.14 23.89 24.91 24.65 24.01 23.70 24.68 24.63 26.13 -- 24.83 24.83 Table VI Unknown Finished Product Samples vs. "Assayed-Sample Standard" Finished Product (Finished Product Containing Sodium Lauryl Ether Suloeate) Sample # FTIR Using Using Titration Unsubtracted Solvent-Subtracted Abs Value Abs Value Lab. # 1 15.04 ) • = 15.04 15.17 ) -- 14.49 15.03 15.14 X = 15.16 14.94 15.04 (y = 0.006 15.17 (y = 0.017 -- 15.03 14.94 ) -- 14.99 ) X = 15.11 14.94 X = 15.01 14.97 14.90 15.15 o' = 0.121 15.37 o' = 0.225 -- -- 15.06 15.13 ) X = 15 20 15.32 ) X = 15.44 3 15.26 ' 15.55 15 35 15.21 (y = 0.066 15.46 (y = 0.116 ' -- 15.16 -- 15.03 15'04 ) X = 15.08 ) X = 15.23 4 15.11 15.29 14.78 15.08 (y = 0.035 15.24 (y = 0.066 15.23 An additional advantage of the FTIR method is the capability of storing the "standards" on a floppy disk. Any time a "standard" need be run for quantitation or for qualitative fingerprinting, it is easily accessed by recalling it from the floppy back into an instru- ment file. This recalling procedure takes about five seconds and eliminates the need to rerun the "standard" each time an analysis is required. Extensive work has been done investigating how instrumental variations such as changes in throughput might affect