Non-modified stationary phases for the analysis of basic compounds

Lingeman, H.; Underberg, W.J.M.

doi:10.1016/0165-9936(88)90027-1

Cited by 17 publications

(4 citation statements)

References 7 publications

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“…The retention behavior of basic compounds in these phases was proposed to be dependent primarily on the ion-exchange mechanism and to be controlled predominately by the pH, and the nature and concentration of the organic modifier (Lingeman and Underberg, 1988). Therefore, due to the presence of acidic silanol (SiOH) functions on the surface of this material, silica can only be used as a cation-exchange material, and the higher the pH of the eluent the higher the ion-exchange capacity of this material.…”

Section: Resultsmentioning

confidence: 99%

Investigation on liquid chromatographic separation of basic compounds using silica column with aqueous/organic mobile phase containing triethylamine and acetic acid

Huang

et al. 2004

Biomedical Chromatography

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A high-performance liquid chromatography (HPLC) method using silica column eluted with aqueous solvent mobile phase containing triethylamine (TEA) and acetic acid (ACH) at trace percentages was characterized for the analysis of basic compounds. The key mechanism of this system is ion-exchange accompanying interaction of silanol groups. The increase in the ACH concentration in the mobile phase minimizes the ionization of the silanol group, leading to reduced retention time. However, the greater extent of ionization of silanol caused by the increase of TEA concentration helps to retain basic compounds in the column. Further, the protonated TEA that is positively charged also competes for the ionized silanol group with basic compounds, resulting in the modification of retention time. On the other hand, the retention becomes longer with increasing proportion of either organic or aqueous solvent in mobile phase, and partial replacement of methanol with acetonitrile.

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Section: Resultsmentioning

confidence: 99%

Investigation on liquid chromatographic separation of basic compounds using silica column with aqueous/organic mobile phase containing triethylamine and acetic acid

Huang

et al. 2004

Biomedical Chromatography

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“…A number of separation techniques have been developed to take advantage of the ion-exchange capacity of silica and alumina and its dynamic modification by interaction with ions in the mobile phase [44,49,[267][268][269][270][271]. The isoelectric point pH for silica is about 2 while that for alumina varies from 3.5-9.2, depending on the method of manufacture and the composition of the buffered mobile phase [49,[269][270][271][272][273].…”

Section: Dynamically Modified Inorganic Oxide Adsorbentsmentioning

confidence: 99%

“…Silica and alumina with reversed-phase type mobile phases have been used to separate basic compounds with a pk a > 8 [47,[269][270][271][272][273]. This includes many pharmaceutically active compounds and their metabolites, such as the example shown in Figure 4.15 [271].…”

Section: Dynamically Modified Inorganic Oxide Adsorbentsmentioning

confidence: 99%

The Column in Liquid Chromatography

Poole

1991

Chromatography Today

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“…Additionally, even when ion-pair agents, such as trifluoroacetic acid [14], or ion suppressing agents, such as triethylamine [15], are used, the MS response is greatly decreased. Proposed alternative solutions of using bare silica, dynamically modified silica, or alumina [16,17] have not yet not gained widespread acceptance. Despite these negative effects RP-HPLC is still the most widely used method, because of the fast equilibration time, the selectivity characteristics, and the retention reproducibility.…”

Section: Introductionmentioning

confidence: 99%

High‐performance liquid chromatography of some basic drugs on a n‐octadecylphosphonic acid modified magnesia‐zirconia stationary phase

Feng²,

et al. 2005

J of Separation Science

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The high-performance liquid chromatographic behavior of some basic drugs was studied on a n-octadecylphosphonic acid modified magnesia-zirconia (C18PZM) stationary phase. The effect of mobile phase variables such as methanol content, ionic strength, and pH on their chromatographic behavior was investigated. The retention mechanism of basic drugs on the stationary phase was elucidated. The results indicate that both hydrophobic and cation-exchange interactions contribute to solute retention under most chromatographic conditions. The inherent Brönsted-acid sites and also the adsorbed Lewis base anionic buffer constituents on accessible ZM surface Lewis acid sites play a role in the retention of ionized solutes by cation-exchange interaction. However, especially at high mobile phase pH, the retention of basic drugs depends mainly on hydrophobic interactions between solutes and support. Separations of the basic drugs on the C18PZM phase by a predominantly reversed-phase retention mode were very promising. The mixed-mode retention feature on this phase, as a result of the adsorbed Lewis base anionic buffer constituents acting as sites for cation-exchange, could also be very useful, e.g. for enhancing the chromatographic selectivity of such analytes. The C18PZM seems to be an excellent alternative to silica-based reversed-phase stationary phase for the separation of strongly basic solutes.

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Non-modified stationary phases for the analysis of basic compounds

Cited by 17 publications

References 7 publications

Investigation on liquid chromatographic separation of basic compounds using silica column with aqueous/organic mobile phase containing triethylamine and acetic acid

Investigation on liquid chromatographic separation of basic compounds using silica column with aqueous/organic mobile phase containing triethylamine and acetic acid

The Column in Liquid Chromatography

High‐performance liquid chromatography of some basic drugs on a n‐octadecylphosphonic acid modified magnesia‐zirconia stationary phase

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