Bromophenol blue, methyl red, bromocresol
green, disperse orange
3, bromocresol purple, fluorescein, and cresol red were purchased
from FUJIFILM Wako Pure Chemical Corporation (Osaka, Japan). EA, DET,
and TMA were purchased from Alfa Aesar Co. (Great Britain). All other
reagents were of analytical grade and used as received. For the fabrication
of the DCP, Whatman chromatography paper grade 1 (200 × 200 mm,
pure cellulose paper) was obtained from GE Healthcare (China). The
designed DCPs were printed on a sheet of Whatman grade #1 using a
wax printer (ColoQube 8570DN, Xerox, USA) followed by heating at 120
°C for 2 min on a drying machine. Wax ink was used for the paper
hydrophobization and an insulation agent in this work.
The DCP
consisted of circles with an inside diameter of 5 mm and a border
of 2 mm (after melting wax ink). To prepare the DCP, the circles were
filled with 10 μL of 0.10 mM dye solutions and dried for 1 h
at room temperature. The colors of the DCP were recorded with a smartphone.
The spots on DCP with different dyes were assigned as shown inFigure 7 .
green, disperse orange
3, bromocresol purple, fluorescein, and cresol red were purchased
from FUJIFILM Wako Pure Chemical Corporation (Osaka, Japan). EA, DET,
and TMA were purchased from Alfa Aesar Co. (Great Britain). All other
reagents were of analytical grade and used as received. For the fabrication
of the DCP, Whatman chromatography paper grade 1 (200 × 200 mm,
pure cellulose paper) was obtained from GE Healthcare (China). The
designed DCPs were printed on a sheet of Whatman grade #1 using a
wax printer (ColoQube 8570DN, Xerox, USA) followed by heating at 120
°C for 2 min on a drying machine. Wax ink was used for the paper
hydrophobization and an insulation agent in this work.
The DCP
consisted of circles with an inside diameter of 5 mm and a border
of 2 mm (after melting wax ink). To prepare the DCP, the circles were
filled with 10 μL of 0.10 mM dye solutions and dried for 1 h
at room temperature. The colors of the DCP were recorded with a smartphone.
The spots on DCP with different dyes were assigned as shown in