Phosphoric Acid

Applications:

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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

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Benzenesulfonic Acid
Bromide
Chlorate
Chloride
Citric Acid
Dextromethorphan
Fumaric Acid
Maleic Acid
Organic Acids
Perchlorate
Phosphoric Acid
Pyrilamine
Succinic Acid
Tartaric Acid
Verapamil
p-Toluenesulfonic Acid (PTSA)

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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, 3.2x150 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

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Phosphoric Acid
Phosphorous acid

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