ABSTRACT
The first historical use of micellar phases in chromatography was with the Gel Permeation Chromatography technique (GPC) (see Chapter 3). The low efficiency problem was not noted in the early use of micellar phases because GPC is not a technique that produces sharp peaks. However, Armstrong observed very early that the TLC micellar spots were broader than nonmicellar ones [ 1 ]. Broad peaks, /. e., poor efficiency, were obtained when micellar mobile phases were used instead of classical hydro-organic mobile phases in classical LC [2, 3]. Dorsey attributed the reduced micellar efficiency to a poor wetting of the apolar stationary phase by the aqueous surfactant phase [3]. He proposed the addition of 3% 1-propanol to remediate the problem [3,4]. Yarmchuck et al. thought that a slow mass transfer between the micelles and the stationary phase was responsible for reduced efficiency [5]. Armstrong [6], Berthod [7] and Hinze [8] concluded that poor mass transfer within the stationary phase itself was mainly responsible for the observed low efficiency. Two main approaches were proposed to enhance the efficiency in MLC: (i)-the addition of low amounts (3% v/v) of 1-propanol [3] to decrease the amount of adsorbed surfactant and to increase the stationary phase wetting, (ii)-to raise the temperature [4, 5] to reduce the liquid viscosity and to increase the chemical reaction rates.
