Salting-out homogeneous liquid-liquid extraction in narrow-bore tube: Extraction and preconcentration of phthalate esters from water

In this study a simple and rapid sample preparation technique, homogeneous liquid-liquid extraction based on phase separation in the presence of a salt performed in a narrow-bore tube, followed by GC-flame ionization detection has been developed. In this work, sodium chloride and ACN were used as the salting-out agent and water-soluble extraction solvent, respectively. The homogeneous solution of water and ACN was broken by addition of the salt. Small volume of ACN was collected on top of the tube and the extracted analytes in the collected phase were determined. It has been successfully used for the analysis of five phthalate esters as model compounds in aqueous sample. Experimental parameters affecting the extraction efficiency such as kind and volume of the water-soluble organic solvent, length and diameter of the tube, and pH of the sample solution were investigated. Under the optimal conditions, the LODs were between 0.02 and 0.7 g/L and enrichment factors were in the range of 172-309. In addition, good linearity (between 1 and 5000 g/L) and high precision on the base of RSD (<8%, C = 600 g/L, n = 6) were achieved.