An Ultraperformance Liquid Chromatography Tandem-Mass Spectrometry Method for Determination of Multiclass Pharmaceuticals in Water Sample by Dispersive Liquid-Liquid Microextraction Combined with Ultrasound Assisted Reverse Extraction from Solidified Floating Organic Droplets.

A novel, simple, and reliable ultraperformance liquid chromatography tandem-mass spectrometry (UPLC-MS/MS ) assay based on dispersive liquid-liquid microextraction followed by ultrasound-assisted reverse extraction from solidified floating organic droplets was established for determination of multiclass pharmaceuticals in the water sample. Six commonly used drugs of various therapeutic classes: ibuprofen, ketorolac, lamotrigine, propranolol, pantoprazole, and losartan were extracted from water samples by using 50 μL 1-undecanol as extracting solvent and 400 μL acetonitrile as dispersive solvent. After collecting the floating organic droplets by cold centrifugation, an ultrasound-assisted back extraction procedure was performed to make the sample compatible for UPLC-MS/MS analysis. Acquity BEH C column (2.1 × 100; 1.7 μm) was used for separation of target analytes that were eluted by a gradient mobile phase composition of 15 mM ammonium acetate and acetonitrile at a flow rate of 0.25 mL/min. The sample ionization was performed by using electrospray ionization in positive mode, and multiple reaction monitoring was used for quantification of target analytes. After optimizing the assay conditions, all calibration curves were found to be linear with limit of detection and limit of quantification were ranged in between 0.06-0.15 and 0.16-0.41 ng/mL, respectively. The enrichment factor was found to be 172-192-fold and the relative recovery was ranged between 93.1 and 109.4% between target analytes. These satisfactory results confirmed that the proposed method is specific and reliable for application of trace analysis of target analytes in waste water samples.