Comparison of the performance of non‐ionic and anionic surfactants as mobile phase additives in the RPLC analysis of basic drugs

Abstract

Surfactants added to the mobile phases in reversed-phase liquid chromatography (RPLC) give rise to a modified stationary phase, due to the adsorption of surfactant monomers. Depending on the surfactant nature (ionic or non-ionic), the coated stationary phase can exhibit a positive net charge, or just change its polarity remaining neutral. Also, micelles in the mobile phase introduce new sites for solute interaction. This affects the chromatographic behavior, especially in the case of basic compounds. Two surfactants of different nature, the non-ionic Brij-35 and the anionic sodium dodecyl sulfate (SDS) added to water or aqueous-organic mixtures, are here compared in the separation of basic compounds (β-blockers and tricyclic antidepressants). The reversible/irreversible adsorption of the monomers of both surfactants on the stationary phase was examined. The changes in the nature of the chromatographic system using different columns and chromatographic conditions were followed based on the changes in retention and peak shape. The study revealed that Brij-35 is suitable for analyzing basic compounds of intermediate polarity, using "green chemistry", since the addition of an organic solvent is not needed and Brij-35 is a biodegradable surfactant. In contrast, RPLC with hydro-organic mixtures or mobile phases containing SDS required high concentrations of organic solvents.

A Novel Nonionic Micellar Liquid Chromatographic Method for Simultaneous Determination of Pseudoephedrine, Paracetamol, and Chlorpheniramine in Cold Compound Preparations

“…SDS is commercially available in high purity at a relatively low cost, and it can dissolve proteins in biological matrices allowing direct injection of the samples in the chromatographic system. [14] GilAgustí et al [15] determined APIs in cough-cold preparations by MLC with SDS. Martínez-Algaba et al [16] systematically analyzed preparations containing antihistamine drugs by MLC using CTAB.…”

“…[17] Brij-35, in the mobile phase of RP-HPLC, can yield appropriate retention time [14] and produce no ultraviolet absorption. [18] García-Á lvarez-Coque et al [19] developed a reversed-phase liquid chromatography method without organic solvent to determine tricyclic antidepressants.…”

Simultaneous isocratic separation of phenolic acids and flavonoids using micellar liquid chromatography

“…Despite the various reports on the feasibility of MLC in the pharmaceutical analysis of drugs and other biologically active compounds , there are only a few reports about the analysis of natural polyphenolic compounds using MLC , but none of them have reported the simultaneous separation of phenolic acids and flavonoids. In this study, the simultaneous isocratic separation of five phenolic acids (galic, chlorogenic, caffeic, p ‐coumaric, and ferulic acid) and four flavonoids (myricetin, morin, quercetin, and kaempferol) were investigated in three different RPLC modes using hydro‐organic mobile phase, micellar mobile phase as well as mobile phases containing SDS in concentrations lower than the CMC (submicellar LC ).…”

Reversed‐phase liquid chromatography without organic solvent for determination of tricyclic antidepressants

“…More recently, the use of micellar mobile phases containing the nonionic surfactant polyoxyethylene(23)lauryl ether ((C 2 H 4 O) 23 C 12 H 25 OH, known as Brij‐35) has been explored as an alternative to separate basic compounds by RPLC []. Due to the neutral bilayer created on the stationary phase, and the smaller polarity of the polyoxyethylene chain, the retention times for basic drugs are shorter with regard to those obtained with SDS.…”

“…Brij‐35 is a biodegradable surfactant, which gives rise to a promising example of “green” liquid chromatography to separate compounds that usually require aqueous–organic mobile phases with a high amount of organic solvent. In the literature, however, only few reports have been published on the analytical use of this or other nonionic surfactants (Brij‐35 [], Tween 80 [], and Triton X‐100 []). Recently, extensive use of Brij‐35 has been reported in the field of quantitative structure–activity relationships [], due to its capability to mimic biopartitioning processes.…”