Meanwhile, developing reagent water is an inexpensive, easily
accessible and environment-friendly solvent compared to organic
solvents commonly used in chromatography. The BPB dotted on
the paper runs altogether with water and reacts with BSA, leaving
a blue dot where the BSA was immobilized. Color disparities of the
blue dots indicate different concentrations of BSA. The remnant of
BPB was washed to the end of paper strip by water, rather than
staying with the blue dot and thus affecting the analysis of colors.
Moreover, this method does not require an exact volume of
samples. Fig. 3 showed that different volumes of samples with the
same concentration could present almost the same color density,
as long as they could fully spread on paper. This indicates that precise
measurement of sample volume could be eliminated when the
experiment is conducted in developing countries under rough conditions.
According to our observation, the spot would expand with
the increase of solution volume, while the color intensity remains
unchanged.
In respect to the results, we could either judge with naked eyes
or take photos of the paper strips and analyze it with image software
Quantity One. The pictures could also be telecommunicated
if necessary. All the results are semiquantitative.