Maleic acid

HPLC Analysis of Cough and Cold Medications Active Ingredients and Acidic Counterions on Heritage MA Mixed-Mode Column
Application description

There are several groups of compounds which are used as active and inactive ingredients in various over-the-counter drug compositions. These compounds are different in nature and can be organic and inorganic. Most of the active ingredients are either hydrophobic basic, hydrophilic basic or hydrophilic neutral compounds. Basic active ingredients of cough and cold remedies used as salts of organic and inorganic acids. The most commonly used hydrophobic active ingredients are doxylamine, pyrilamine, chlorpheniramine, brompheniramine, and dextromethorphan. Doxylamine is an antihistamine drug, used to relieve symptoms of allergy, hay fever, and the common cold. Doxylamine is used in combination with other active ingredients to provide effective nighttime relief from cough and cold symptoms. Pyrilamine is an antihistamine drug, which targetsH1 receptors as an inverse agonist. Brompheniramine is an antihistamine drug of propylamine nature. Chlorpheniramine is an antihistamine used to treat symptoms such as allergic rhinitis. Dextromethorphan is a medication mostly used as a cough suppressant. It is a morphine type of medication with sedative, dissociative, and stimulant properties. Succinic acid is a hydrophilic diacid that is used as a counterion. Maleic acid is hydrophilic diacid which is used as a counterion. Both compounds have very limited retention even in RP-AQ columns. Due to the strongly hydrophobic and basic properties of these compounds, they demonstrate a poor peak shape in traditional reversed-phase chromatography due to the overloading of residual silanol groups on the surface when these basic drugs are analyzed. In addition to this, hydrophilic counterions are not retained in RP because there is no mechanism of retention for these acidic hydrophilic compounds. Both problems were eliminated by using Heritage MA reversed-phase anion-exchange column. Column and method demonstrate high efficiency and good peak shape for acidic and basic analytes. It can be used to develop methods for various cough, cold, and congestion compositions without the use of ion-pairing reagents. Compounds are well retained by a combination of one or more mechanisms. The column is compatible with 100% ACN and 100% water as well as with most buffers with pH 1.5-7. Various additives to the mobile phase can be used based on the nature of samples and detection techniques.

Conditions of Experiment
Column: Heritage MA
Separation Modes: reversed-phase, cation-exclusion, anion-exchange
Column Dimenstions: 4.6x150 mm, 3 um, 100A
Mobile Phase: 5% ACN with 30 mM AmFm pH 3
Detection: UV 275
Sample: various
Injection: 3 uL
Flow rate: 1 ml/min
Analytes
Class of compounds: Amines, Aromatic base, Drug, Organic acid, Pyridine
Nature of compounds: Acidic, Basic, Hydrophilic, Hydrophobic, Polar
Compounds: Doxylamine, Pyrilamine, Succinic acid, Chlorpheniramine, Brompheniramine, Maleic acid, Dextromethorphan
Simultaneous HPLC Analysis of Brompheniramine and Maleic Acid Counter-Ion on Heritage MA Column
Application description

The analysis of drugs and counterions usually requires two methods; one for the drug and another one for the counter-ion. This is true for basic and acidic drugs, as well as basic and acidic counter-ions. Brompheniramine is an antihistamine drug used in many cough and cold formulations (Nyquil, Avil, Dimetapp, Vick’s, etc). Brompheniramine is hydrophobic and basic in nature. Reversed-phase chromatography usually produces poor peak shape for this highly hydrophobic and basic compound due to the overloading of residual silanols on the surface of silica gel. Maleic acid is a common counter-ion used in drug production and various formulations. It has two carboxylic acid fragments with pKa of 1.94 and 6.22. It is very polar in nature due to the presence of two ionizable groups. We have developed a separation approach for analysis of basic drug and acidic counter-ion. The order of elution for brompheniramine and maleic acid can be changed by changing the amount of ACN, buffer pH and buffer concentration. The Heritage MA is a mixed-mode anion-exchange and cation-exclusion column. The basic ionizable group on the surface of silica gel shields silanols from interacting with the basic group in bromnehiramine, thus producing a perfect peak shape. The method is LC/MS compatible and no ion-pairing reagent is required to retain basic drug or acidic counter-ion retention time. The elution on the Heritage MA column is controlled by the amount of ACN, buffer concentration and buffer pH. The buffer pH, concentration control ion-exchange, ion-exclusion mechanisms and amount of ACN are controlling the hydrophobic retention of compounds analyzed on this mixed-mode column

Conditions of Experiment
Column: Heritage MA
Separation Modes: reversed-phase, cation-exclusion, anion-exchange
Column Dimenstions: 4.6 x 150 mm, 5 um, 100A
Mobile Phase: ACN/water/ammonium formate
Detection: UV 255 nm
Sample: 0.3 mg/ml
Injection: 3 uL
Flow rate: 1 ml/min
Analytes
Class of compounds: Aromatic base, Drug, Organic acid
Nature of compounds: Acidic, Basic, Hydrophilic, Hydrophobic, Polar
Compounds: Brompheniramine, Maleic acid
HPLC Analysis of Six Organic Acids on Heritage MA Mixed-Mode Column
Conditions of Experiment
Column: Heritage MA
Separation Modes: reveresed-phase, anion-exchange
Column Dimenstions: 4.6 x 150 mm, 5 um, 100A
Mobile Phase: 35% ACN with 50 mM AmFm pH 3
Detection: UV 255 nm
Sample: 0.2 mg/ml
Injection: 5 uL
Flow rate: 1 ml/min
Analytes
Class of compounds: Aromatic acid, Organic acid, Preservative
Nature of compounds: Acidic, Hydrophilic, Hydrophobic, Polar
Compounds: Gallic acid, 4-Hydroxybenzoic acid, Caffeic acid, Mandelic acid, Maleic acid, Atrolactic acid
HPLC Analysis of Hydrophilic Acids on Coresep SB Column in Reversed-Phase and Anion-Exchange Modes
Application description

Mixture of hydrophilic acidic compounds are separated in reversed-phase anion-exchange mode on core-shell mixed-mode column. Method is robust, reliable and fast and can be used for analysis of underivatized acids without ion-pairing reagent.

Conditions of Experiment
Column: Coresep SB
Separation Modes: reversed-phase and anion-exchange
Column Dimenstions: 3.2 x 100 mm, 2.7 um, 90A
Mobile Phase: 50% ACN with 50 mM sodium phosphate (monobasic) pH 3
Detection: UV 230 nm
Sample: 0.3 mg/ml
Injection: 3 uL
Flow rate: 0.5 mg/ml
Analytes
Class of compounds: Aromatic acid, Organic acid
Nature of compounds: Acidic, Hydrophilic, Polar
Compounds: Benzoic acid, Maleic acid, Fumaric acid