Determination of Dechlorane compounds in aqueous samples using ultrasound-assisted dispersive liquid-liquid microextraction and gas chromatography-electron-capture negative ion-mass spectrometry

A simple and solvent-minimized procedure for the rapid determination of chlorinated flame retardants, Dechlorane compounds: syn-and anti-Dechlorane Plus (syn-and anti-DP), Dechlorane (Dec) 602, Dec 603 and Dec 604, in aqueous samples is described. The method involves the use of ultrasound-assisted dispersive liquid-liquid microextraction (UA-DLLME) prior to their determination by gas chromatography-electron-capture negative ion-mass spectrometry (GC-ECNI-MS) operating in the selected-ion-monitoring (SIM) mode. The parameters affecting the extraction efficiency of analytes from water samples were systematically investigated. The best extraction conditions involved the rapid injection of a mixture of 1.0 mL of acetonitrile (as a dispersant) and 60 μL of carbon tetrachloride (as an extractant) into 10 mL of water sample containing 0.5 g of sodium chloride in a conical bottom glass tube. After ultrasonication for 1.0 min and centrifugation at 5000 rpm (5 min), the volume of the sedimented phase was adjusted to 20 μL and the analytes were then determined by GC-ECNI-MS analysis. The limits of quantitation (LOQs) ranged from 0.08 to 0.3 ng L^-1. The precision for these analytes, as indicated by relative standard deviations (RSDs), was less than 9% for both intra-and inter-day analyses. Accuracy, expressed as the mean extraction recovery, was between 75 and 92%. A preliminary result revealed that trace levels of Dechlorane compounds were detected in various water samples with total concentrations ranging from 0.6 to 0.9 ng L^-1.