*4.4. Sample Preparation*

Ground maize samples were spiked with ZON at the concentration range of 5 ng/kg to 10 µg/kg (5, 10, 50, 100, and 500 ng/kg and 1, 5, and 10 µg/kg). One gram aliquots of the spiked samples were extracted with 10 mL of acetonitrile/water (6:4) as a solvent. The samples were stirred for 10 min and centrifuged on ultrafiltration membranes with a 100,000 nominal molecular weight limit at 5000 rpm for 10 min, and the filtrate was collected for OWLS and ELISA measurements. Upon sample preparation, all samples were stored at 4 ◦C until measurement and were diluted with 42 mM Tris buffer (pH 7.4) to the appropriate rate prior to analysis.
