Simultaneous Determination of Aflatoxins in Pistachio Using Ultrasonically Stabilized Chloroform/Water Emulsion and HPLC

Abstract

Simultaneous determinations of aflatoxins (AFs) in pistachio at μg/kg concentrations were performed using ultrasonic chloroform/water emulsion microextraction (USAEME) and HPLC-UV measurement. A chloroform/water emulsion was stabilized using ultrasonic agitation for the purification of AFs extracted from pistachios using methanol/water. Because the method effectively purified and concentrated AFs, the AFs could be measured directly and without further preconcentration using HPLC-UV. Preparation of AF derivatives for fluorescence measurement was not required. In the optimized procedure, the AF calibration curves were linear for all AFs with correlation coefficients that ranged from 0.9913 to 0.9994. The detection limit was between 0.3 and 1.4 μg/kg, and quantification limit was obtained between 1.1 and 3.2 μg/kg (n = 3); the largest relative standard deviation was obtained <9.78 % (n = 3) at 3 μg/kg, and recoveries ranged from 81.2 to 101.6 % at spiking levels of 0.4, 0.8, 2, and 4 μg/kg. Application of this method to the measurement of AFs in pistachio samples indicated that USAEME coupled with HPLC-UV can determine trace AF levels. The USAEME method is simple, sensitive, and cost-effective in comparison to previous methods.