| Abstract
| - The kinetics of the absorption and desorption of analytesfor headspace liquid-phase micoextraction (HS-LPME)were studied. It was found that the desorption of analytesfrom the extraction phase into the sample matrix isisotropic to the absorption of the analytes from the samplematrix into the extraction phase under the same conditions. This therefore allows for the calibration of absorption using desorption. Calibration was accomplished byexposing the extraction phase, which contained a standard, to the sample matrix. The information from thedesorption of the standard, such as time constant a, couldbe directly used to estimate the concentration of the targetanalyte in the sample matrix. This new kinetic calibrationmethod for headspace LPME was successfully used tocorrect the matrix effects in the BTEX analysis of anorange juice sample. In this study, the headspace LPMEtechniques were successfully fully automated, for bothstatic and dynamic methods, with the CTC CombiPalautosampler. All operations of headspace LPME, including sample transfer and agitation, filling of extractionsolvent, exposing the solvent in the headspace, withdrawing the solvent to syringe and introducing the extractionphase into injector, were autoperformed by the CTCautosampler. The fully automated headspace LPME technique is more convenient and improved the precision andsensitivity of the method. This automated dynamic headspace LPME technique can be also used to obtain thedistribution coefficient between the sample matrix (aqueous or another solution) and the extraction phase(1-octanol or another solvent). The distribution coefficientbetween 1-octanol and orange juice, at 25 °C, wasobtained with this technique.
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