Spectrofluorimetric and circular dichroism approaches for sulfasalazine determination using serum proteins: JMP optimization and quantitative studies

Abstract

Circular dichroism (CD) based spectroscopic methods (zero and second-order derivative), as well as the fluorescence-based method, were developed for the assay of sulfasalazine (SZ) in pharmaceutical formulation and in biological sample using the proteins bovine serum albumin (BSA) and human serum albumin (HSA). The proposed methods are simple and selective for SZ determination. Fluorescence spectra of proteins (method A) show a peak at 340 nm, and a zero order CD scan (normal CD) shows a negative peak at 208 nm (method B). The calibration curve (method A) shows linearity in between 2.91 and 7.41 μg mL−1 for the BSA-SZ system and between 2.44 and 7.83 μg mL−1 for the HSA-SZ system. For method B, the linearity is between 3.38 and 6.10 μg mL−1 for BSA-SZ system, while it is between 2.91 and 6.10 μg mL−1 for the HSA-SZ system. The derivative CD spectrum i.e., second order CD spectrum (D2) exhibits two bands, positive band at 208 nm (method C) and another negative band at 195 nm (method D). Linear calibration curves for CD based methods were in the concentration range of 3.38–6.10 μg mL−1 for BSA-SZ and 2.91–6.10 μg mL−1 for HSA-SZ systems. ICH guidelines were used for the validation of the proposed methods. To demonstrate their suitability for sulfasalazine quality control in its dosage forms, the proposed methods were compared to the reference method.