Retention studies on mixed-mode columns in high-performance liquid chromatography

Validation of high-performance liquid chromatography assay for quantification of formoterol in urine samples after inhalation using UV detection technique

“…In this study the pH of the mobile phase was lowered to pH 3 to avoid these problems. When the pH is lowered, the silanols become protonated [25], thus eliminating the attractions between the ionised silanol groups and the NH 2 groups of the solutes.…”

Simultaneous determination of positive and negative pharmaceutical counterions using mixed-mode chromatography coupled with charged aerosol detector

“…The columns that exhibit both reversed-phase and ion-exchange (anionic, cationic or zwitterionic) behavior are most common type of mixed-mode columns [14][15][16][17][18][19]. Recently, mixed-mode columns with HILIC (hydrophilic interaction liquid chromatography) behavior have become increasingly popular in the separation of highly polar molecules including ions being weakly or not retained by conventional reversed-phase LC systems [20][21][22][23][24].…”

Selective retention of basic compounds by metal aquo-ion affinity chromatography

“…Mixed-mode HPLC can be achieved by connecting two columns with an ODS and a cation-exchange stationary phase [38], by packing two types of stationary phases, reversed phase and ionexchange, in a column [39,40], and by chemically binding an ionizable group in an alkyl chain on a silica-based support [41,42]. The preparation of the heat-treated metal-silica gel developed in this study is very simple.…”