Combination of homogeneous liquid-liquid extraction and vortex assisted dispersive liquid-liquid microextraction for the extraction and analysis of ochratoxin A in dried fruit samples: Central composite design optimization

This paper presents a new analytical procedure based on combination of homogeneous liquid-liquid extraction (HLLE) and vortex-assisted dispersive liquid-liquid microextraction (VA-DLLME) for the accurate and reliable determination of ochratoxin A (OTA) in dried fruit samples. To enable selective extraction of the OTA, six hydrophobic deep eutectic solvents (hDESs) were prepared and tested as extraction solvents. Optimization of DES volume, pH, NaCl amount, and mixing time affecting the efficiency of VA-DES-DLLME step was achieved by central composite design (CCD). Using optimized conditions, the working range was obtained in the range 0.4-350 ng mL-1 with an enrichment factor of 138. The limit of detection was 0.12 ng mL-1. To evaluate the accuracy of the method, the samples were analyzed with both the HLLE-VA-DES-DLLME procedure and reference method. The precision of the method was investigated by intraday/interday studies. The robustness of the method was also evaluated by making minor changes to the optimized conditions. The HLLE-VA-DES-DLLME procedure was successfully applied to dried fruit samples and quantitative recoveries were obtained (92.1-99.2%) confirming its usefulness for implementation in routine analysis of food samples.