Determination of propranolol enantiomers in plasma and urine by spectrofluorimetry and second-order standard addition method

The determination of propranolol enantiomers in human plasma and urine by spectrofluorimetry and a second-order standard addition method is described. The methodology is based on chiral recognition of propranolol by formation of an inclusion complex with β-cyclodextrin, a chiral auxiliary, in the presence of 1-butanol. The adopted strategy combines the use of PARAFAC, for extraction of the pure analyte signal, with the standard addition method, for determinations in the presence of an individual matrix effect caused by the quenching action of the proteins present in the plasma and urine. A specific PARAFAC model was built for each sample, in triplicate, and the scores were related to (R)-propranolol mole fraction using a linear regression in the standard addition method. Using a propranolol with concentration of 260 ng mL⁻¹, good results were obtained for determinations in the mole fraction range from 50 to 80% of (R)-propranolol, providing absolute errors between 0.4 and 3.6% for plasma and between 0.9 and 6.0% for urine.