Dissolved carbon dioxide flotation: an effective way for phase separation in emulsification microextraction method

Dissolved carbon dioxide flotation after emulsification microextraction (DCF-EME) technique coupled with gas chromatography-electron capture detection (GC-ECD) was introduced for preconcentration and determination of six organochlorine pesticides (OCPs) in seawater samples. DCF-EME method is based on the rapid and simple phase separation of low density organic solvent from the aqueous phase via introducing of a saturated NaHCO3 solution (9.6% w/v) into the acidified sample solution (0.1M of HCl) containing analytes. Thanks to the in situ generation of carbon dioxide (CO2) bobbles intensified by ultrasound radiation, the dispersed extraction solvent was collected to the surface of the aqueous sample and then was narrowed to the capillary part of a special home-made extraction cell for facile retrieving. Under the optimal conditions, the limits of detection were at the range of 2.6-9.2 ng L(-1) and preconcentration factors were varied between 271 and 307 for different OCPs. The applicability of the developed method was evaluated by the extraction and determination of the target analytes from Caspian seawater samples.