2.4. Extraction procedure for ochratoxin A
The samples were extracted according to the method as described by Iqbal et al. (2013) with few modifications. The sample 15 g was blended (15 min) in 50 ml of acetonitrile-water (45:05, v/v), using high speed blending and then the extract was filtered through filter paper. About 5ml of the filtratewas mixed with 50 ml of phosphate buffer saline (PBS) and filtered through a glass microfiber.Then 10 ml of the filtrate was passed through immunoaffinity columns. OTA was eluted from the column by passing 1.5 ml of methanol (HPLC grade) and collected in a vial. The eluate was evaporated until dryness at 40 C and residues were redissolved in 1 ml of mobile phase i.e. acetonitrile-watereacetic acid (47/51/2, v/v/v) for HPLC analysis. The flow rate of mobile phasewas 1 ml/min while the excitation and emissionwavelengths
of fluorescence detector were set at 333 and 460 nm, respectively