| An air-assisted liquid–liquid microextraction
method coupled with a multivariate calibration method,
namely partial least squares (PLS), was developed for
the extraction and simultaneous determination of benzoic
acid (BA) and sorbic acid (SA) via a spectrophotometric
approach. In this work, a two-step microextraction method
was used. In the first step, analytes were extracted from
acidic aqueous solution into octanol, as an organic solvent,
and in the second step, the analytes were simultaneously
back-extracted into an alkaline aqueous solution. The high
absorption signal of octanol was the main reason to perform
this back-extraction step. The effects of different parameters
on the method efficiency were investigated; the parameters
included extraction solvent volume, ionic strength
of aqueous solution, pH, number of extraction cycles, and
aqueous sample volume. Under optimum conditions, calibration
graphs were seen to be linear over the range of 0.1–
2.0 μg mL−1 for the both analytes. Other analytical parameters
were obtained as follows: Enrichment factors (EFs)
were found to be 14.98 and 13.03, and limits of detection
were determined to be 0.03 and 0.04 μg mL−1 for BA and
SA, respectively. As the last step, binary mixtures of the
analytes were prepared and simultaneously extracted using
the proposed method. Finally, PLS modeling was used for
multivariate calibration of spectrophotometric data. It was successfully utilized for the analysis of the target analytes
in real samples. |