Chromatographic retention behaviour, modelling and separation optimisation of the quaternary ammonium salt isometamidium chloride and related compounds on a range of reversed-phase liquid chromatographic stationary phases

Abstract

This paper describes the reversed-phase liquid chromatographic behaviour of the trypanocidal quaternary ammonium salt isometamidium chloride and its related compounds on a range of liquid chromatographic phases possessing alkyl and phenyl ligands on the same inert silica. In a parallel study with various extended polar selectivity phases which possessed different hydrophobic/silanophilic (hydrogen bonding) activity ratios, the chromatographic retention/selectivities of the quaternary ammonium salts was shown to be due to a co-operative mechanism between hydrophobic and silanophilic interactions. The highly aromatic and planar isometamidium compounds were found to be substantially retained on stationary phases containing aromatic functionality via strong π-π interactions. The chemometric approach of principal component analysis was used to characterise the chromatographic behaviour of the isometamidium compounds on the differing phases and to help identify the dominant retention mechanism(s). Two-dimensional (temperature/gradient) retention modelling was employed to develop and optimise a rapid liquid chromatography method for the separation of the six quaternary ammonium salts within 2.5 min which would be suitable for bioanalysis using liquid chromatography-mass spectrometry. This is the first reported systematic study of the relationship between stationary phase chemistries and retention/selectivity for a group of quaternary ammonium salts.

Evaluation of chromatographic columns packed with semi‐ and fully porous particles for benzimidazoles separation

“…Methodologies such as response surface analysis (RSA) can help to visualize which are the main experimental variables affecting separation. It models the responses, finds the optimal combination of factors, and it can predict the most suitable experimental conditions . A factorial design was used to evaluate the effect of each potential optimization variable on the separation performance.…”

An injectable thermosensitive hydrogel with a self-assembled peptide coupled with an antimicrobial peptide for enhanced wound healing

“…Hydrogel is considered to be a moist wound environment, which is a breeding ground for microorganisms and can promote wound infection. Therefore, a series of antimicrobial agents such as antibiotics, 20 metal ions or oxides, 21,22 antimicrobial peptides 23 and quaternary ammonium salt compounds 24 are added into hydrogels to enhance their antimicrobial activity. 25 Moreover, bacterial resistance caused by antibiotics is also a problem that cannot be ignored.…”

Simultaneous determination of tetrabutyl ammonium and tetrabutyl phosphonium in environmental water samples by solid phase extraction and ion chromatography

“…There are reports of quaternary ammonium salts detection using the ion chromatography method and [13][14][15][16] mass spectrometry method. [17][18][19][20] Analysis methods for quaternary phosphonium salts are rarely reported, only the infrared spectrum and nuclear magnetic resonance (NMR) have been studied, possibly due to the structure and chemical properties of the quaternary phosphonium salts being similar to quaternary ammonium salts. However, reports of long chain quaternary ammonium salts and quaternary phosphonium salts analysis were scarce.…”