With the validated detection principle and color reading protocol, we then tested the microchip for the quantitation of malathion.Fig. 4(a) shows a scanned image of the microchannels with malathion concentrations increasing from 0 to 8 g/mL (left to right). It is clear that the yellow color fades gradually as the concentration of the pesticide increases. Fig. 4(b) is the plot showing the relationship between the yellow intensity determined from the image and the concentration of malathion solution. The decreasing trend is similar to that of the absorbance change depicted in Fig. 2(b). In Fig. 4(c)