Determination of parabens in wastewater and sludge in a municipal wastewater treatment plant using microwaveassisted dispersive liquid-liquid microextraction coupled with gas chromatography-mass spectrometry

Background: Due to the complexities involved in the extraction of micropollutants, the informationregarding micropollutants like paraben in wastewater and sludge is scarce. The aim of this study wasto adopt a microwave-assisted dispersive liquid-liquid micro-extraction (MADLLME) method for theextraction of parabens in municipal wastewater treatment plant (WWTP).Methods: A mixed stock solution of methyl-, ethyl-, propyl-, and butyl-parabens with concentration of10 mg/mL were prepared in methanol. To validate this method, the limit of detection (LOD), limit ofquantification (LOQ), linearity, and m/z were measured. To adopt this method in different condition,the effect of pH (3, 7, 9, and 12), microwave power (180, 300, 450, and 600 W), solvent type (methanol,acetone, methanol/water, acetone/water), and 1 g folorisil were assessed. After adopting MADLLMEmethod, the paraben fate of this WWTP was evaluated through mass loading and emission.Results: The optimum performance of MADLLME method was observed at pH = 7, microwave power= 450 W, reaction time = 30 s, and methanol as the solvent. The total concentrations of four parabenmetabolites in the WWTP ranged between 2505 ng/L in influent, 1953 ng/L in effluent, and 8.03 ng/gat wet weight sludge samples. The total mass loading and emission of four parabens in this WWTP was0.672 mg/d/1000 people and 0.186 mg/d/1000 people, respectively.Conclusion: MADLLME method seems to be an excellent alternative, as a green extraction technique,for determining various groups of emerging micropollutants in different matrices.

Keywords:

Paraben , Environment , Municipal sludge , Dispersive liquid-liquid micro-extraction , Microwave-assisted extraction