A comparison of gas-liquid chromatography, NMR spectroscopy and Raman spectroscopy for determination of the substituent content of general non-ionic cellulose ethers

This paper describes and compares three techniques that can be used to char acterize the substituent content of hydroxypropylcellulose (HPC and L-HPC) and hydroxypropyl methylcellulose (HPMC): gas-liquid chromatography (GLC) w ith a BP1 column and FI detection, C-13-NMR spectroscopy of hydrolysed samp les, and Raman spectroscopy. GLC and C-13-NMR spectroscopy both allow indep endent quantification of hydroxypropoxyl and methoxyl contents. C-13-NMR sp ectroscopy, though requiring lengthier sample preparation, has the advantag e of also quantifying the degree of substitution at each substitutable gluc opyranose hydroxyl. Raman spectroscopy may be useful for rapid approximate estimation of hydroxypropoxyl content. (C) 1999 Elsevier Science B.V. All r ights reserved.