Highly sensitive spectrofluorimetric method for rapid determination of orciprenaline in biological fluids and pharmaceuticals

Orciprenaline sulphate (ORP) is a direct-acting sympathomimetic with mainly beta-adrenoceptor stimulant activity. It is used as a bronchodilator in the management of reversible airway obstruction. For the first time, a rapid highly sensitive spectrofluorimetric method is described that is relied on measuring the fluorescence spectra of ORP at acidic pH and without addition of any chemical reagents. The relative fluorescence intensity was measured at 310 nm and after excitation at 224 nm. ORP native fluorescence was calibrated in both water and acetonitrile as diluting solvents. The method was designed to estimate the drug in miscellaneous matrices with high accuracy and precision. Linear ranges of calibration curves were 30.0-400.0 ng/ml and 10.0-240.0 ng/ml in water and acetonitrile, respectively. The detection limits were calculated and reached as low as 3.3 and 3.1 ng/ml, respectively, representing the ultra-sensitivity of the proposed method. This result permitted application of this method for spiked human plasma and urine and was used as a preliminary investigation with good percentage recovery (89.4-106.8%). The application was further extended to analyse ORP in its pharmaceutical formulations. The method was validated in compliance with International Council of Harmonization (ICH) Guidelines.