Liquid chromatography - quadrupole Orbitrap mass spectrometry method for selected pharmaceuticals in water samples

This study developed an analytical approach for sub-ppb level detection and confirmation of 13 pharmaceuticals and personal care products (PPCPs) in water samples using ultra high pressure liquid chromatography hyphenated with a quadrupole Orbitrap mass spectrometer (UHPLC- Q-Orbitrap-MS). Sample preparation was performed by using solid phase extraction (SPE) employing hydrophilic-lipophilic balance cartridges, with elution of sorbed analytes using methanol. Acceptable automatic gain control (AGC) target and maximum injection time (IT) were 1×10⁶ and 200ms, respectively, resulting in a mass accuracy <2ppm. High response signals with sufficient data points per peaks (20-30) were obtained whilst maintaining high resolution of approximately 70,000 full width at half maximum. Extracted ion chromatograms provided quantitative analysis with linearity (R²) ranging from 0.9875 to 0.9993 and method detection limits ranging from 0.01-0.61ngmL^-1. Compounds were further analysed by MS/MS analysis, with the MS operated in parallel reaction monitoring (PRM) mode under precursor ion analysis intervals and collision energies chosen for the different PPCPs. The developed method was applied to analyse water samples obtained from sources in Victoria, Australia.