Because the chromate has a relatively intensive yellow color, by taking a picture of the microchip, a densitogram of each microcolumn can be created by means of a densitometric software (e.g. CP Atlas 2.0, freeware thin layer chromatogram evaluation software) [29]. The densitograms, that is the plots of intensity (RGB values) of colors per pixels of the picture of the microcolumn, are shown in Fig. 4c. The yellow area of the Cr(VI) can be simply integrated by the same software, and this integrated area is proportional to the sample concentration loaded onto the microcolumns (Fig. 4d.). The calibration plot of the Cr(VI) standard solutions adsorbed on the microchip showed good linearity (R2 = 0.9902). Actually, the determination of high concentration (> 20 μg/mL) Cr(VI) is possible by this colorimetric procedure (taking photo and making densitogram) without using FAAS. For the detection of samples containing less than 20 μg/mL concentration (10 μL) Cr(VI), more sensitive atomic spectrometric detection is necessary.