Determination of cyclic and linear siloxanes in wastewater samples by ultrasound-assisted dispersive liquid–liquid microextraction followed by gas chromatography–mass spectrometry

• Published in: Talanta (Oxford) 2014-03, Vol.120, p.191-197
• Main Authors: Cortada, Carol, dos Reis, Luciana Costa, Vidal, Lorena, Llorca, Julio, Canals, Antonio
• Format: Article
• Language: English
• Subjects: Design engineering; Design factors; Experimental design; Gas chromatography; Gas Chromatography-Mass Spectrometry - methods; Limit of Detection; Liquid Phase Microextraction - methods; Siloxanes; Siloxanes - analysis; Solvents; Sonication; Spectrometry; Spectroscopy; Ultrasound-assisted dispersive liquid–liquid microextraction (USA-DLLME); Volatile siloxanes; Waste water; Waste Water - analysis; Wastewater; Water Pollutants, Chemical - analysis
• ISSN: 0039-9140; 1873-3573
• DOI: 10.1016/j.talanta.2013.11.042

A fast, simple and environmentally friendly ultrasound-assisted dispersive liquid–liquid microextraction (USA-DLLME) procedure has been developed to preconcentrate eight cyclic and linear siloxanes from wastewater samples prior to quantification by gas chromatography–mass spectrometry (GC–MS). A two-stage multivariate optimization approach has been developed employing a Plackett–Burman design for screening and selecting the significant factors involved in the USA-DLLME procedure, which was later optimized by means of a circumscribed central composite design. The optimum conditions were: extractant solvent volume, 13µL; solvent type, chlorobenzene; sample volume, 13mL; centrifugation speed, 2300rpm; centrifugation time, 5min; and sonication time, 2min. Under the optimized experimental conditions the method gave levels of repeatability with coefficients of variation between 10 and 24% (n=7). Limits of detection were between 0.002 and 1.4µgL−1. Calculated calibration curves gave high levels of linearity with correlation coefficient values between 0.991 and 0.9997. Finally, the proposed method was applied for the analysis of wastewater samples. Relative recovery values ranged between 71 and 116% showing that the matrix had a negligible effect upon extraction. To our knowledge, this is the first time that combines LLME and GC–MS for the analysis of methylsiloxanes in wastewater samples. [Display omitted] •Siloxanes in wastewater cause engine damages and poor performance of biogas.•LLME is used for the first time for siloxanes determination in wastewater samples.•Ultrasound-assisted dispersive liquid–liquid microextraction is used as LLME technique.•Experimental design has been used for optimizing the microextraction conditions.•The new method is simple, fast, easy to handle, sensitive and environmentally friendly.