Determination of pharmaceuticals in fish and wastewater using isotope dilution high performance liquid chromatography-tandem mass spectrometry.

A method has been developed for the trace analysis of 15 pharmaceuticals and employs liquid chromatography/tandem mass spectrometry (LC-ESI-MS/MS). Unlike many previous methods, which suffer from matrix suppression and recovery loss, the present method utilizes isotope dilution for each compound to correct for these phenomena. Matrix spike recoveries for all compounds were between 87 and 113% for wastewater effluent, 98 and 144% for fish fillet tissue, and 81% and 105% for fish liver tissue. Method Detection limits (MDLs) in wastewater, fish fillet, and liver tissue were ≤21, ≤13, and ≤41 ng/g, respectively for most analytes. Additionally, this method was directly compared with matrix matched calibration to evaluate potential to compensate for matrix effects. Matrix matched was not suitable to account for matrix effects in samples with highly loaded matrix such as fish liver, though this method offered greater sensitive compared to isotope dilution in the detection of some compounds such as norfluoxetine, sertraline, and fluoxetine.