Simultaneous determination of atenolol, propranolol, dipyridamole and amiloride by means of non-linear variable-angle synchronous fluorescence spectrometry Original Research Article

First derivative non-linear variable-angle synchronous fluorescence spectrometry has been developed to improve the selectivity of fluorescence measurements without loss of sensitivity. It allows the rapid simultaneous determination of different substances in a mixture from a single spectrum based on a single scan. This method was applied for the simultaneous determination of atenolol (ATE), propranolol (PRO), amiloride (AMI) and dipyridamole (DIP) at concentrations between 10–400, 6–200, 5.6–280 and 5–100 ng ml−1, respectively, by means of absolute values of first derivative of non-linear variable-angle synchronous scan at λex/λem=228.8/300, 287.2/340, 366.4/412.8 and 288/487.2 nm for ATE, PRO, AMI and DIP, respectively. In order to obtain maximum sensitivity and an adequate selectivity, factors affecting fluorescence intensity were studied. As a result, the analyses were performed in an ethanol–water (70%(v/v)) medium at a pH 7.5, adjusted by using trishydroxymethyl amino methane (0.08 M) as a buffer solution. Analytical parameters of the proposed method were calculated according to the error propagation theory. The sensitivity, repeatability, reproducibility and limit of detection achieved with the proposed method are adequate for the determination of these doping substances.