Diclofenac in municipal wastewater treatment plant: quantification using laser diode thermal desorption—atmospheric pressure chemical ionization—tandem mass spectrometry approach in comparison with an established liquid chromatography-electrospray ionization–tandem mass spectrometry method

•LDTD method for rapid analysis of diclofenac in wastewater and sludge was developed.•The method provides accurate results in 12s in comparison with LC approach.•ASE and USE were tested for the extraction of diclofenac from sludge.•The fate of diclofenac in wastewater treatment plant was studied.•LDTD approach can be applied for the analysis of high matrix environmental samples. Diclofenac (DCF), a prevalent non-steroidal anti-inflammatory drug (NSAID) is often detected in wastewater and surface water. Analysis of the pharmaceuticals in complex matrices is often laden with challenges. In this study a reliable, rapid and sensitive method based on laser diode thermal desorption/atmospheric pressure chemical ionization (LDTD/APCI) coupled with tandem mass spectrometry (MS/MS) has been developed for the quantification of DCF in wastewater and wastewater sludge. An established conventional LC-ESI–MS/MS (liquid chromatography-electrospray ionization–tandem mass spectrometry) method was compared with LDTD-APCI-MS/MS approach. The newly developed LDTD-APCI-MS/MS method reduced the analysis time to 12s in lieu of 12min for LC-ESI–MS/MS method. The method detection limits for LDTD-APCI-MS/MS method were found to be 270ngL−1 (LOD) and 1000ngL−1 (LOQ). Furthermore, two extraction procedures, ultrasonic assisted extraction (USE) and accelerated solvent extraction (ASE) for the extraction of DCF from wastewater sludge were compared and ASE with 95.6±7% recovery was effective over USE with 86±4% recovery. The fate and partitioning of DCF in wastewater (WW) and wastewater sludge (WWS) in wastewater treatment plant was also monitored at various stages of treatment in Quebec Urban community wastewater treatment plant. DCF exhibited affinity towards WW than WWS with a presence about 60% of DCF in WW in contrary with theoretical prediction (LogKow=4.51).