Quantification of residual cetyltrimethylammonium bromide (CTAB) and sodium deoxycholate (DOC) in Haemophilus influenzae type b (Hib) polysaccharide using NMR

CTAB and DOC are used as reagents in the purification of Hib polysaccharide. Polysaccharide is purified by precipitation with CTAB from fermented broth followed by solvent extraction and DOC is used to remove the protein impurities. The reagents used in the purification process should be removed from the product as per regulatory requirements. These two residual reagents can be easily identified and quantified in purified Haemophilus influenzae type b polysaccharide by NMR. The LOD of these residual reagents is 0.1% (10 μg/mL) and LOQ is 0.5% (50 μg/mL) with respect to polysaccharide determined from the spectrum. The absence of the peaks corresponding to CTAB and DOC in the NMR spectrum of purified polysaccharide confirms either they are absent or present at less than 0.1%. The present study provides supporting data from the regulatory viewpoint, which can help in circumventing the time-consuming studies for the vaccine manufacturers to develop different analytical methods for identification and quantification of CTAB and DOC as per regulatory requirements.