Development and validation of a capillary electrophoresis method for the characterization of sulfoethyl cellulose

To characterize sulfoethyl cellulose el samples, a capillary electrophoresis method was developed and validated sulfoethyl cellulose el was hydrolyzed, and the resulting d ‐glucose derivatives were analyzed after reductive amination with 4‐aminobenzoic acid using 150 mM boric acid, pH 9.5, as background electrolyte at 20°C and a voltage of 28 kV. Peak identification was derived from capillary electrophoresis with mass spectrometry using 25 mM ammonia adjusted to pH 6.2 by acetic acid as electrolyte. Besides mono‐, di‐, and trisulfoethyl d ‐glucose small amounts of disaccharides could be identified resulting from incomplete hydrolysis. The linearity of the borate buffer‐based capillary electrophoresis method was evaluated using d ‐glucose in the concentration range of 3.9–97.5 μg/mL, while limits of detection and quantification derived from the signal‐to‐noise ratio of 3 and 10 were 0.4 ± 0.1 and 1.2 ± 0.3 μg/mL, respectively. Reproducibility and intermediate precision were determined using a hydrolyzed sulfoethyl cellulose el sample and ranged between 0.2 and 8.8% for migration times and between 0.3 and 10.4% for peak area. The method was applied to the analysis of the degree of substitution of synthetic sulfoethyl cellulose el samples obtained by variation of the synthetic process and compared to data obtained by elemental analysis.