Analysis of Water-Soluble Polymers in Toothpaste by FT-Raman Spectrometry

The determination of water-soluble polymers in toothpaste is highly important for the analysis and the quality control of the products, because the water-soluble polymers dominate the performance of the products. We improved method for determining the water-soluble polymers in toothpaste by means of FT-Raman spectrometry. Its measurement method is similar to FT-IR's one, and measuring operation is simple and speedy. The measuring time is only 15 minutes to one sample. It was confirmed by FT-Raman spectrometry that each typical water-soluble polymers, i.e. sodium carboxymethylcellulose (CMC), carrageenan, hydroxyethylcellulose (HEC), xanthan gum, sodium polyacrylate, showed some characteristic peaks. They were applicable to the qualitative analysis thereof, and we did not need troublesome data analysis. The calibration curve obtained in terms of peak-height ratios at 856cm-1 (carrageenan) vs at 936cm-1 (CMC) showed a high linear relation curve. We could calculate simply and quickly mixture ratio of CMC to carrageenan by the calibration curve. The pretreatment methods for separate water-soluble polymers from toothpaste were only easy solvent extraction and dialysis, because FT-Raman spectrometry is little interfered by some impurities. We applied the analysis procedures to 4 tubes of test toothpaste. The result was that they analysis procedures was proved to be effective and reliable in analyzing the commercial products.