Fast determination of propranolol in urine and pharmaceutical preparations by stopped-flow and micellar-stabilized room-temperature phosphorescence: validation of the method

Abstract

The stopped-flow mixing technique has been used to study the kinetic determination of propranolol by means of micellar-stabilized room-temperature phosphorescence. This mixing system diminishes the time required for the deoxygenation of micellar medium by sodium sulfite, allowing a kinetic curve that levels off within only 7 s to be obtained. The phosphorescence enhancers thallium (I) nitrate, sodium dodecyl sulfate, and sodium sulfite were optimized to obtain maximum sensitivity and selectivity. A pH value of 6.54 was selected as adequate for phosphorescence development. The kinetic curves of propranolol phosphorescence were scanned at λ ex=290 nm and λ em=524 nm. The calibration graphs were linear for the concentration range from 25 to 400 ng mL −1. The phosphorescence lifetime of propranolol is approximately 1210 μs. The detection limit calculated as proposed clayton was 13.53 ng mL −1 and by applying the error propagation theory, the detection limit was 8.37 ng mL −1. The repeatability was studied using 10 solutions of 200 ng mL −1 of propranolol; if error propagation theory is assumed, the relative error is 1.94%. The standard deviation for a replicate sample was 4.0 ng mL −1. This method was successfully applied to the determination of propranolol in commercial formulations and in urine. Suitable recovery values were obtained.