In comparison with conventional ELISA kits which have better detection limits and other chip-based detection methods by electrochemical measurements , the method developed here in is more suitable for on-site OP detection due to its simple procedure and low cost. Only four steps are required in the detection,consisting of sample extraction, injection and agitation, and then reading with an office scanner. Without further optimization, the sensitivity of this system is 100 ppb, which is much lower than the WHO threshold level (2.0 ppm for malathion in whole meal) . It is always favorable to perform chromatographic detection (HP-LC,GC–MS) to quantify OP pesticides, however, the cost and complex-ity of operation and equipment limits their availability for rapid,on-site detection. The low cost, sufficient sensitivity and ease ofuse allow the adaption of this colorimetric method for point-of-collection screening, where traditional analytical instrumentationis not always advantageous