A simple high performance liquid chromatography method HPLC-UV for simultaneous enantiomeric determination of propranolol, metoprolol, pindolol, and atenolol in natural water samples was developed and validated, using a molecularly imprinted polymer solid-phase extraction. To achieve this purpose, Lux(®) Cellulose-1/Sepapak-1 (cellulose tris-(3,5-dymethylphenylcarbamate)) (Phenomenex, Madrid, Spain) chiral stationary phase was used in gradient elution and normal phase mode at ambient temperature. The gradient elution program optimized consisted of a progressive change of the mobile phase polarity from n-hex/EtOH/DEA 90/10/0.5 (v/v/v) to 60/40/0.5 (v/v/v) in 13 min, delivered at a flow rate of 1.3 ml/min and a sudden change of flow rate to 2.3 ml/min in 1 min. Critical steps in any molecularly imprinted polymer extraction protocol such as the flow rate to load the water sample in the cartridges and the breakthrough volume were optimized to obtain the higher extraction recoveries for all compounds. In optimal conditions (100 ml breakthrough volume loaded at 2.0 ml/min), extraction recoveries for the four pairs of β-blockers were near 100%. The MIP-SPE-HPLC-UV method developed demonstrates good linearity (R(2) ≥ 0.99), precision, selectivity, and sensitivity. Method limit detection was 3.0 µg/l for propranolol and pindolol enantiomers and 20.0 and 22.0 µg/l for metoprolol and atenolol enantiomers, respectively. The proposed methodology should be suitable for routine control of these emerging pollutants in natural waters for a better understanding of the environmental impact and fate.
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