Evaluation of phenylazonaphthols water-micelle interphase distribution using TLC data

Abstract

The chromatographic behavior of two synthesized phenylazonaphthols 4-(phenylazo)-1-naphthol-2-
sulphonic acid (PANS) and 4-(4-sulphophenylazo)-1-naphthol-2-sulphonic acid (SPANS) on direct (Sorbfil),
reversed (RP-18) and polyamide-6 TLC plates in micellar mobile phases of sodium dodecylsulfate (SDS) and
triton X-100 (TX-100) was investigated. The detection and quantitative measurements of chromatograms in
TLC were conducted using a Sorbfil videodensitometer (Sorbopolymer, Russia). Experimental RF data were
used for calculation of water-micelle Kmw and water-stationary phase (SP) Ksw, partition coefficients, as well
as energy of analytes transfer ∆Gtrans from water to micelle and energy sorption ∆Gsorp on SP using
D.Armstrong three-phase model. It was shown that a plot of RF /(l - RF ) vs. Cm, (the concentration of
micelles in the mobile phase in g/mL) gives a straight line with slope (Vm/Vs
)((Kmw - l)ν/Ksw) and intercept
(Vm/Vs)(l/Ksw). Thus Kmw values were calculated using ν values for SDS 0.862 mL/g and for TX-100 0.912
mL/g). It was demonstrated that partition coefficients of PANS and SPANS depends on the hydrophobicity
of reagents, type of micelles and in some extent the nature of plate sorbent.