Determination of sulphathiazole and sulphanilamide by photochemically induced fluorescence and first-derivative fluorescence

This manuscript reports the usefulness of the determination of sulphathiazole (ST) using photochemically induced fluorescence (RTPF) and RTPF coupling with first derivative (D1-RTPF), and the determination of sulphanilamide (SAN) by meaning first derivative of the emission spectrum. By irradiating 5 min, with intense UV radiation, sulphathiazole, in ethanol:water 20:80 (v/v) solutions at pH 4.5-5.0, show fluorescence emission at 342 nm (λex = 251 nm). Under these conditions, a linear relation, fluorescence intensity-ST concentration, was found between 0.23 and 3.00 μg mL−1 of ST. The method was applied for determining ST in a pharmaceutical drug. ST was also determined in honey by using the D1-RTPF signal, applying the standard addition method, and measuring at 324.8 nm. Under the same experimental conditions of pH and solvent, a fluorimetric method for determining SAN in presence of ST is proposed. Calibration graphs for SAN determination were established using the amplitude of the first derivative of the emission spectrum measured at 324.4 nm, as the analytical signal. This method has been applied to determining SAN in a pharmaceutical formulation.