Applications:
HPLC Analysis of Basic Drugs and Acidic Counter-Ions by Mixed-Mode Chromatography

The majority of drugs in the pharmaceutical industry are administered in salt form. The presence of two counter-ions very often necessitates the use of two methods. The nature of these counterparts in drugs can be an inorganic cation and organic acid, inorganic anion and organic base, and organic cation and organic anion. Furthermore, the properties of the molecules will result in a differing stoichiometry. The task of simultaneous quantitation of counter-ions can be achieved by using mixed-mode columns. The general approach for analysis is based on properties of corresponding counter-ions. Hydrophobic basic drugs, like dextromethorphan, verapamil, trimipramine, and corresponding acidic counter-ions (chloride, chlorate, bromide, bromate, perchlorate, maleate, fumarate,tartrate, succinate, phosphate, citrate, benzosulfonate, toleuensulfonate) can be separated and quantitated in the same run on reversed-phase anion-exchange column. Basic hydrophobic drugs are retained by the reversed-phase mechanism, and counter-ions are retained by the reversed-phase and anion-exchange mechanism. Some polar counter-ions are retained only by the anion-exchange mechanism. Retention time and selectivity of HPLC separation of drugs and counter-ions can be achieved by changing the amount of acetonitrile and the amount of ions in the mobile phase. The detection technique depends on the properties of the counter-ions. In case of low or no UV activity, ELSD can be employed if the counter-ion forms a non-volatile salt with the mobile phase additive (ammonium formate). This HPLC method can be used for simultaneous quantitation of other basic drugs and counter-ions. The presence of two mechanisms of retention allows control over retention times of drug and counter-ion independently, and even allows a change of order of elution when necessary.
Condition
Column |
Primesep D , 4.6x150 mm, 5 µm, 100A |
Mobile Phase |
MeCN/H2O |
Buffer |
AmFm pH 3.0 |
Flow Rate |
1.0 ml/min |
Detection |
ELSD, UV 270 |
Description
Class of Compounds |
Ions, Hydrophilic, Hydrophobic, Base, Acids, Ionizable |
Analyzing Compounds |
Sodium Chloride, Sodium chloride, Sodium Chlorate, Sodium bromide, Sodium bromate, Perchloric Acid, Maleic Acid, Fumaric Acid, Tartaric Acid, Succinic Acid, Phosphoric Acid, Citric acid, Benzosulfonic acid, Dextromethorphan, Verapamil, Trimipramine |
Benzenesulfonic AcidBromideChlorateChlorideCitric AcidDextromethorphanFumaric AcidMaleic AcidOrganic AcidsPerchloratePhosphoric AcidPyrilamineSuccinic AcidTartaric AcidVerapamilp-Toluenesulfonic Acid (PTSA)
HPLC Separation of Phosphorous and Phosphoric Acids
Application Notes: Phosphorus and phosphoric acid were separated on Obelisc N and Primesep D columns. On Obelisc N both acids retained by combination of HILIC and anion-exchange mechanisms. OnPrimesep D these inogranic acids are retained by anion-exchange mechanism. Both columns and methods can be used for analysis of hydrophilic organic and inorganic acids with multi-mode or single mode approach
Application Columns: Primesep D, Obelisc N
Application compounds: Phosphorous Acid, Phosphoric Acid
Detection technique: UV, LC/MS, ELSD/CAD
Condition 1
Column |
Primesep D, 3.2x50 mm, 5 µm, 100A |
Mobile Phase |
MeCN |
Buffer |
AmFm |
Flow Rate |
0.5 ml/min |
Detection |
ELCD |
Condition 2
Column |
Obelisc N, 4.6x50 mm, 5 µm, 100A |
Mobile Phase |
MeCN |
Buffer |
AmFm |
Flow Rate |
0.5 ml/min |
Detection |
ELSD |
Description
Class of Compounds
|
Acid, Fungicide, Hydrophilic, Ionizable |
Analyzing Compounds |
Phosphorous Acid, Phosphoric Acids |
Phosphoric AcidPhosphorous acid
HPLC Separation of Ethylphosphonic, Methylphosphonic, Methylenediphosphonic and Phosphoric Acids on Newcrom B Column
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Condition
Column |
Newcrom B, 4.6x150 mm, 5 µm, 100A |
Mobile Phase |
MeCN/H2O - 20/78% |
Buffer |
Formic Acid - 2% |
Flow Rate |
1.0 ml/min |
Detection |
CAD |
Description
Class of Compounds |
Acids, Hydrophilic, Ionizable |
Analyzing Compounds |
Ethylphosphonic acid, Phosphoric, Methylphosphonic Acid, Methylenediphosphonic acid |
Ethylphosphonic AcidMethylenediphosphonic acidMethylphosphonic AcidPhosphatePhosphoric Acid
HPLC Separation of Glyphosate, Glyphosine, Ethylphosphonic, Methylphosphonic, Methylenediphosphonic and Phosphoric Acids on Newcrom B Column
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Condition
Column |
Newcrom B, 4.6x150 mm, 5 µm, 100A |
Mobile Phase |
MeCN Gradient -40-10%, 15 min |
Buffer |
Formic Acid Gradient -1- 5%, 15 min |
Flow Rate |
1.0 ml/min |
Detection |
CAD |
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Description
Class of Compounds |
Acids, Plant growth regulator, Herbicide, Hydrophilic, Ionizable |
Analyzing Compounds |
Ethylphosphonic acid, Phosphate Ion, Methylphosphonate, Methylenediphosphonic acid, Glyphosate, Glyphosine |
Ethylphosphonic AcidGlyphosateGlyphosineMethylenediphosphonic acidMethylphosphonic AcidPhosphatePhosphoric Acid
HPLC Separation of Phosphoric and Phosphorous Acids on Newcrom B Column
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Condition
Column |
Newcrom B, 4.6x150 mm, 5 µm, 100A |
Mobile Phase |
MeCN/H2O - 20/80% |
Buffer |
Formic Acid - 2% |
Flow Rate |
1.0 ml/min |
Detection |
CAD (Corona) MS- compatible mobile phase |
Description
Class of Compounds |
Hydrophilic, Acid |
Analyzing Compounds |
Phosphoric acid, Phosphorous acid |
Phosphoric AcidPhosphorous acid