Vortex-Assisted Liquid–Liquid Microextraction Combined with HPLC for the Simultaneous Determination of Five Phthalate Esters in Liquor Samples

Vortex-assisted liquid–liquid–liquid microextraction (VALLLME) technique: A new microextraction approach for direct liquid chromatography and capillary electrophoresis analysis

“…In this technique, an organic solvent (e.g., 1-octanol, hexane, chloroform, hexanoic acid, etc.) is dispersed into the aqueous sample using vortex agitation to form a mild emulsification (fine droplets) without involving any dispersive solvent [10,[14][15][16][17]. The droplets that are formed are able to accelerate the extraction due to the large surface area and shorter diffusion distance compared to the DLLME technique [10].…”

“…Both high and low density organic solvents can be used, depending on the affinity of the target analytes. The VALLME technique was successfully applied for the extraction of diverse analytes such as alkyl phenols [10,16], haloanisoles and halophenol [17], pesticides [18][19][20][21], herbicides [22], phthalate esters [14,15], polychlorinated biphenyls [23], furfurals [24], perfluorooctanesulfonate [25] and aliphatic amines [26]. In order to improve the extraction efficiency and/or phase separation, several modifications such as the addition of surfactant [14,18,19,22], ultrasound agitation [21], aeration [27], centrifugation [15,25,26] and salt addition [24] were used.…”

“…Although the organic extracts have been directly analyzed using reversed phase HPLC, poor reproducibility of retention times and resolution are sometimes observed [10,15,16,[24][25][26][27]. The non-compatible nature of the organic extracts and the reversed phase HPLC resulted in long retention of the organic solvent in the column.…”

“…The non-compatible nature of the organic extracts and the reversed phase HPLC resulted in long retention of the organic solvent in the column. Strategies to overcome this problem include diluting the organic extract with methanol, extension of the HPLC analysis time and conditioning of the column after the elution of the peaks [10,15,16,[24][25][26][27]. These attempts lead to low extraction yield, is not only time consuming but consumes large amounts of mobile phase [10,15,16,24].…”

“…Strategies to overcome this problem include diluting the organic extract with methanol, extension of the HPLC analysis time and conditioning of the column after the elution of the peaks [10,15,16,[24][25][26][27]. These attempts lead to low extraction yield, is not only time consuming but consumes large amounts of mobile phase [10,15,16,24]. The lack of selectivity of the two phase VALLME procedure also poses interferences when applied to real samples [15,16,24,25].…”