Effect of Acid in Mobile Phase on Retention of Neutral, Acidic, Basic and Zwitterionic Compounds on Core-Shell Mixed-Mode Column
Application description

Seven compounds with different properties were used to study an effect of different acids in the mobile phase on retention of neutral, acidic, basic and zwitterionic compounds on core-shell mixed-mode Coresep 100 column. Retention of neutral compounds (propylparaben and benzoic acid to some extent) are not affected by change of the acid. Basic compounds (norphenylephrine, pyridine, 2-aminopyridine) respond the most to change of the strength of acidic additive. Several folds increase in retention time was observed when sulfuric acid was replaced with formic acid in the mobile phase. Effect of acid on retention time of zwitterionic amino acids was less pronounced but still provided excellent retention and peak shape for zwitterionic compounds (5-aminosalicylic acid, phenylalanine). This methods and Coresep 100 column can be used to retain and separate other acidic, basic, neutral and zwitterionic compounds without the use of ion-pairing reagent in the mobile phase. Various detection techniques can be used based on the properties of the mobile phase and analytes. Methods are compatible with mall major detection techniques 9UV, ELSD, CAD, RI, MS). Core-shell mixed-mode columns provide great combination of unique selectivity, speed and efficiency.

Conditions of Experiment
Column: Coresep 100
Separation Modes:
Column Dimenstions: 4.6 x 150 mm, 2.7 um, 90A
Mobile Phase:
Detection: UV 255 nm
Flow rate: 1 mL/min
Class of compounds: Amines, Amino acid, Aromatic acid, Aromatic base, Aromatic compound, Catecholamine, Drug, Isomer, Neurotransmitter, Organic acid, Preservative, Pyridine, Supplement
Nature of compounds: Acidic, Basic, Hydrophilic, Hydrophobic, Neutral, Polar, Zwitterionic
Compounds: 5-Aminosalicylic acid, Norphenylephrine, Phenylalanine, Pyridine, Benzoic acid, 2-Aminopyridine, Propylparaben
HPLC Analysis of Preservative Propylparaben on Heritage C18 Column According to US Pharmacopeia
Application description

United States Pharmacopeia establishes written procedures for analysis of drugs, food ingredients, dietary supplement products and other ingredients. These standard procedures are used by pharmaceutical, chemical and other companies to ensure identity and purity of various compounds. Propylparaben, along with methylparaben and ethylparaben, is a preservative used in water-based cosmetics and food. Parabens are hydrophobic neutral compounds that can be easily retained on a Heritage C18 HPLC column. Analysis and column are robust and reproducible and can be used in determination of parabens in various samples. Retention time is controlled by amount of ACN or MeOH in the mobile phase. Buffers and additives can be chosen to accommodate different detection techniques.

Conditions of Experiment
Column: Heritage С18
Separation Modes: reversed-phase
Column Dimenstions: 4.6x150 mm, 5 um, 100A
Mobile Phase: 50% MeCN with 20 mM NaH2PO4 pH 2.5
Detection: UV 254 nm
Sample: 0.3 mg/ml
Injection: 5 uL
Flow rate: 1 mL/min
Class of compounds: Aromatic compound, Preservative
Nature of compounds: Hydrophobic, Neutral
Compounds: Propylparaben