UPLC-MS/MS screening method for simultaneous identification and characterisation of acidic and basic pharmaceuticals
A new screening method was developed for the simultaneous determination of seven acidic and basic pharmaceuticals by the ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) utilising triple quadrupole mass spectrometry as a detector. The target pharmaceutical compounds of interest in this work belong to different classes of pharmaceutical group with different physico-chemical properties. Both the positive and negative ionisation modes (dual ionisation mode) in electrospray ionisation (ESI) were used simultaneously. Unlike previous studies, the performance of the dual ionisation mode was compared with the positive and negative ionisation modes individually in terms of analysis time and sensitivity. Results indicate that the developed screening method was successfully applied for the simultaneous determination of the acidic and basic pharmaceutical compounds. Using dual ionisation mode reduced the analyses time while still maintaining sensitivity and quality of the analytical result. The new method was implemented in detecting the targeted analyte in a real sample of wastewater. The instrument detection limit (IDL) was as low as 9.7 fg, indicating a high sensitivity as compared to the corresponding methods. The precision of the instrument was calculated as the relative standard deviation (RSD) ranging from 1.4 to 11.0%. The limit of quantification (LOQ) for the method was over the range 0.77–177 ng L−1 and 1.05–100 ng L−1 for the influent and effluent wastewater, respectively.
