A validated HPLC assay for salmon calcitonin analysis. Comparison of HPLC and biological assay

A high-performance liquid chromatographic (HPLC) method is described for the assay of salmon calcitonin. The method uses a 5-microns octadecasilyl silica column (100 x 4.6 mm) at 50 degrees C and an initial mobile phase (flow rate 1 ml min-1) comprising 35% of B (1 M tetramethylammonium hydroxide-water-acetonitrile, 8:392:600) and 65% of A (1 M tetramethylammonium hydroxide-water-acetonitrile, 20:880:100) with linear gradient elution over 21 min to a final mobile phase of 57% B; solutions A and B are adjusted to pH 2.5 with phosphoric acid. Detection was by UV spectrophotometry at 210 nm. The method has been shown to be selective, precise and rapid and, in a collaborative study to give excellent correlation with the results obtained by using the biological assay method of the European Pharmacopoeia. The method, which has been applied successfully to the assay of different batches of salmon calcitonin in bulk drug and in formulated products, is recommended for adoption as the pharmacopoeial assay method.