Determination of some β-blockers and β₂-agonists in plasma and urine using liquid chromatography-tandem mass spectrometry and solid phase extraction

A highly sensitive method for the determinations of acebutolol, clenbuterol, nadolol, oxprenolol, propranolol, terbutaline and timolol β-blockers and β₂-agonists in plasma and urine was developed. The method was optimized using electrospray ionization liquid chromatography-tandem mass spectrometry (LC-ESI-MS-MS) and clean screen solid phase extraction cartridges. Matrix effect was reduced by removing co-extractives from the SPE cartridges using methanol prior to drugs' elution. Using blood and serum matrices for calibration and applying the internal standard method has also contributed to the reduction of matrix effect. Method's validation yielded linear dynamic ranges of 5.0-50.0 and 50.0-1000.0 ng/ml for drugs spiked in plasma and urine respectively. It also gave correlation coefficients of 0.94-0.99, detection limits ranged in 0.06-5.04 pg/ml and quantification limits ranged in 0.14-22.88 pg/ml for the target drugs. Developed method was successfully applied to the analysis of β-blockers and β₂-agonists in plasma and urine samples. Plasma samples fortified with drugs at 7.5, 40.0 and 75.0 ng/ml gave percentage recoveries ranged in 78.66-118.10, 67.02-83.97 and 74.77-93.80, respectively. Urine samples fortified with drugs at 80.0, 400.0 and 800.0 ng/ml gave percentage recoveries ranged in 104.68-130.18, 110.23-125.16 and 109.46-116.89, respectively. Variance coefficients ranged in 0.05-0.35 and 0.04-0.12 were, respectively, obtained for the analyses of drugs in plasma and urine samples. Results suggest that developed method is well suited for the analysis of investigated drugs in biological fluids.