Jn. Moorthy et al., PAPER ACIDITY ESTIMATION - APPLICATION OF PH-DEPENDENT FLUORESCENCE PROBES, Journal of photochemistry and photobiology. A, Chemistry, 113(2), 1998, pp. 189-195
The use of pH-dependent fluorescence probes for paper acidity estimati
on has been explored. The changes in emission properties of the four p
robes (quinine bisulphate, fluorescein, pyranine and SNAFL-1, a semina
phthofluorescein dye) in buffer solutions of varying pHs are found to
correlate with the respective changes observed for the probes applied
on paper samples of varying acidity. The remarkable correlations sugge
st that the paper acidity ('pH(app)') can be inferred by extrapolating
the probe behavior on paper samples to that in aqueous solutions of v
arying pHs. Thus, with a judicious choice of pH-dependent fluorescence
probes, a wider range of pH indicators of paper acidity are possible
to be developed. This methodology promises a non-destructive alternati
ve to measure acidity of paper. (C) 1998 Elsevier Science S.A.