Tyrosine

HPLC Separation of Underivatized Amino Acids in Buffer-Less Mode on Coresep 100 Core-Shell Mixed-Mode Column
Application description

Amino acids are very polar compounds which are used as a building blocks in pharmaceutical industry. They are widely used as supplements and food additives. Depending on the pH of the mobile phase they can exist in acidic, basic or zwitter-ionic form. At pH below 3, amino acids are basic in nature and have the highest hydrophobicity. Within pH of 3 to 7 amino acids are in zwitter-ionic form where they are the most hydrophilic. There is no mechanism of retention on reversed-phase column and amino acids are not retained. Bufferless ion-separation (BLIS) was introduced by SIELC as a way to retain and analyze amino acids in reversed-phase cation-exchange mode. This mode allows to analyze amino acids as zwitter-ions without any ions/buffers in the mobile phase. The method was adopted for analysis of amino acids on core-shell mixed-mode columns. A similar approach on a reversed-phase core-shell column results in distorted peaks and no separation or significant retention to achieve baseline separation.

Conditions of Experiment
Column: Coresep 100
Separation Modes: reversed-phase and cation-exchange
Column Dimenstions: 3.2 x 50 mm, 2.7 um, 90A
Mobile Phase: 20% ACN with no additives
Detection: UV 205 nm, ELSD
Sample: 0.3 mg/ml
Injection: 1 uL
Flow rate: 1 ml/min
Analytes
Class of compounds: Amino acid, Supplement
Nature of compounds: Hydrophilic, Polar, Zwitterionic
Compounds: Methionine, Tyrosine, Phenylalanine
Separation of Neurotransmitters on Coresep 100 Column in Reversed-Phase and Cation-Exchange Modes
Application description

Catecholamines (neurotransmitters) are derivatives of the amino acid tyrosine. DOPA, tyrosine, phenylalanine, norepinephrine, epinephrine, and dopamine. Fast and efficient method with base-line separation was achieved on Coresep 100 column. All compounds are separated by combination of reversed-phase and cation-exchange mechanisms. Peak order and retention time can be changed by switching from TFA to ammonium formate in the mobile phase, by adjusting mobile phase composition and by changing pH. The method is fully compatible with mass spectroscopy and can be used for fast analysis of neurotransmitters in biofluids. regular. Method can be used a replacement for analysis of neurotransmitters by UPLC with ion-pairing reagents.

Conditions of Experiment
Column: Coresep 100
Separation Modes: reversed-phase and cation-exchange
Column Dimenstions: 3.2 x 100 mm, 2.7 um, 90A
Mobile Phase: ACN gradient from 5% to 10% in 5 min, buffer gradient - Ammonium formate pH 2.9 from 5 to 25 mM in 5 min
Detection: UV 270 nm, ELSD
Sample: 0.3 mg/ml
Injection: 1 uL
Flow rate: 1 ml/min
Analytes
Class of compounds: Amino acid, Aromatic base, Catecholamine, Drug, Neurotransmitter, Supplement
Nature of compounds: Basic, Hydrophilic, Polar, Zwitterionic
Compounds: Dopamine, Tyrosine, Phenylalanine, Norepinephrine, Epinephrine, DOPA
HPLC Analysis of Underivatized Amino Acids on Coresep S Column in HILIC and Cation-Exchange Modes
Application description

Amino acids serve as building blocks, drugs and nutrients. The usual approach for analysis of amino acids include reversed-phase chromatography with an ion-pairing reagent, derivatization, and hydrophilic interaction chromatography (HILIC). Three amino acids (phenylalanine, tyrosine, and DOPA) were retained and separated in underivatized form in HILIC cation-exchange mode of core-shell mixed-mode HPLC column. This method is fast and reliable and provides base-line separation for all amino acids in the application. Method can be adopted for analysis of other amino acids.

Conditions of Experiment
Column: Coresep S
Separation Modes: HILIC and cation-exchange
Column Dimenstions: 3.2 x 100 mm, 2.7 um, 90A
Mobile Phase: 85 % ACN with 15 mM AmAc pH 5
Detection: UV 270, ELSD
Sample: 0.3 mg/ml
Injection: 3 uL
Flow rate: 0.5-2 ml/min
Analytes
Class of compounds: Amino acid, Catecholamine, Drug, Neurotransmitter, Supplement
Nature of compounds: Basic, Hydrophilic, Polar, Zwitterionic
Compounds: Phenylalanine, Tyrosine, DOPA