Separation of phenylamine- and naphthylaminesulphonic acids by reversed-phase high-performance liquid chromatography - Zou, H.; Zhang, Y.; Wen, X.; Lu, P. (Elsevier)
Mixtures of singly and multiply substituted phenylamine- and naphthylaminesulphonic acids, important intermediates in the synthesis of dyestuffs, were separated by reversed-phase liquid chromatography with UV detection. Linear regression analysis according to the retention equation ln k' = ln k'"w + cC"b [where k'"w is the extrapolated capacity factor at C"b = 0 and c is mainly determined by molecular interaction between the solute and the eluent; they are constants for a given solute at a given column system; C"b is the concentration of organic modifier (v/v)] with and without experimental data at C"b = 0 being taken into account was carried out. The regression coefficient in the former situation is much lower than that in the latter. A linear relationship between ln k'"w (without taking the data at C"b = 0 into account) and the ln k'"w measured at C"b = 0 was obtained. The effect of the eluent acidity on k' is complex, indicating that the negatively charged, neutral and positively charged solutes simultaneously contribute to the retention. The retention value increases with increasing concentration of sodium chloride, but the linear regression analysis according to Horvath's equation ln k' = A + Bm (where A and B are constants related to the physico-chemical behaviour of a given column system and m is the concentration of the inorganic salt) is not good, which may be caused by masking of the ionized silanol group and changing the eluent surface tension simultaneously.
http://linkinghub.elsevier.com/retrieve/pii/0021-9673(90)85027-S
Keywords: V