A simple, high throughput method for the quantification of sodium alginates on oesophageal mucosa

Sodium alginate is a potential bioadhesive, but the lack of a convenient and suitable method for its quantification on the mucosal surface complicates the evaluation of its mucosal retentive properties. This paper develops and evaluates a spectrophotometric method for the rapid quantification of a range of sodium alginates differing in chemical composition, and investigates how quantification was influenced by the presence of oesophageal mucosa. The method, based on dye complexation with 1,9-dimethyl methylene blue (DMMB) was sensitive to alginate molecular weight and uronic acid composition, however, no significant correlations between assay performance and alginate molecular characteristics were demonstrated. The assay was also influenced by complexation time, calcium ions and mucin, but was unaffected by the presence of oesophageal tissue scrapings. The assay proved to be capable of quantifying sodium alginate with excellent linearity (r = 0.999), reproducibility (CV < 3%) and sensitivity (0.3 g l(-1)) and proved to be a precise, high-throughput method that may be used for quantifying the retention of sodium alginate on oesophageal mucosa.