Trace determination of β-blockers and β2-agonists in distilled and waste-waters using liquid chromatography-tandem mass spectrometry and solid-phase extraction.

A highly sensitive method for simultaneous determinations of eleven β-blockers and β-agonists in distilled and waste-waters using liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS-MS) was developed, optimized and validated. The method was used for trace determinations of acebutolol, atenolol, metoprolol, propranolol, timolol, nadolol, labetalol, oxprenolol, pindolol, alprenolol and terbutaline. Oasis MCX and Clean Screen cartridges were used for solid phase extractions and an alkaline mixture of dichloromethane-propanol was used as mobile phase. Matrix effect was reduced by using methanol as a pre-eluant for removing co-extractives on the SPE cartridges and by applying the internal standard method for quantification. Using Oasis MCX-SPE cartridges, developed method gave average recoveries of 77.20-97.30% for drugs spiked at 150.00-500.00pg/ml. Intra-day precisions gave RSD of 3.367-12.489% while as inter-day precisions gave RSD of 6.425-19.768%. Detection limits of 0.11-6.74pg/ml and quantification limits of 0.14-22.88pg/ml were obtained. Signal's suppression in the range of 4.50-24.50% was recorded due to the matrix effect. Drugs spiked in wastewater at 500.00pg/ml concentrations level and stored at 4°C for 6 days, showed insignificant degradation. Developed method was successfully applied to the analysis of pharmaceutical residues in effluents wastewaters. Five β-blockers and one β-agonists were detected in Al-Ain and Abu Dhabi wastewaters at average concentrations of 3.44-19.05pg/ml. Atenolol was detected at higher average concentration ranged in 125.60-234.28pg/ml. Results obtained suggest that adopted wastewater treatment processes are not enough to degrade these compounds.