The width of a microcolumn was increased to 1 mm (in other chip-based chromatographic work, the widths are 0.1 mm [11],[12] and [13]). The length of the microcolumns was limited by the width of the glass slide. After these considerations, the dimension of the microcolumns was 20 mm × 1 mm × 0.1 mm (Fig. 1b), which was useful to produce effluent (after separation or preconcentration of components) in a range of 10–30 μL. These chip-based chromatographic columns already can serve enough volume of sample for the micro-injection FAAS.