Hydrophilic interaction liquid chromatography method development and validation for the assay of HEPES zwitterionic buffer

Abstract

interaction liquid chromatography method development and validation for the assay of HEPES zwitterionic buffer. Manuscript submitted (2016). Acknowledgement: China Scholarship Council (CSC)  A HILIC method for the analysis of HEPES was developed, validated and applied to commercial products from different suppliers.  The influence of different factors on retention time was investigated to get a better understanding of the retention.  The obtained data were evaluated by different retention models and a mixed model of partition and adsorption mechanism was found to fit best, with adsorption being the main retention mechanism, combined with partition and ion exchange mechanisms.  The stress test of HEPES found one degradant under oxidative conditions, identified as N-oxide by high resolution MS.

Quantification of oligopeptide‐20 and oligopeptide‐24 in cosmetic creams using hydrophilic interaction liquid chromatography with electrospray ionization mass spectrometry

“…For this reason, a ZIC®‐HILIC column whose functional group consists of a strongly acidic sulfonic acid group and a strongly basic quaternary ammonium group separated by a short alkyl spacer was chosen. In this zwitterionic stationary phase, the electrostatic forces of each charge are partly counterbalanced by the proximity of ions with opposite charge, and the negatively charged sulfonic acid groups might be responsible for weak, but important, electrostatic interactions, since it is more approachable to interact with the analytes . The chromatographic parameters examined are: the effect of the salt type and concentration, pH value and acetonitrile percentage regarding retention and peak shape with the one‐factor‐a‐time method.…”

Recent applications of retention modelling in liquid chromatography

“…Recently, papers have focused on the optimization of a complete method, looking at different parameters such as buffers, salts, their concentrations, pH, the organic‐modifier content, temperature, and stationary phase. When optimizing the modifier content, a number of studies used the LSS model [131–135], the ADS model [100,131–136], the Q model [100,136], and the MM model [131,133]. Often, more than one model is used to distinguish for example between the partitioning mechanism and the adsorption mechanism [110,111].…”