Amino Acid Analysis

Concise Separation Columns for Amino Acid Analysis

  • Robust polymeric resin stable across the full pH range of 0 to 14
  • High efficiency and strong resolution for complex amino acid mixtures
  • Excellent lot-to-lot and column-to-column reproducibility
  • Available in Li+ form for physiological samples and Na+ form for protein hydrolysates
  • Optimized for post-column derivatization detection workflows

Concise Separations amino acid columns are engineered specifically for ion-exchange chromatography (IEC), the gold-standard technique for amino acid analysis due to its unmatched reproducibility. IEC delivers stable retention times and accurate quantitation regardless of sample matrix, making it ideal for clinical diagnostics, nutritional research, protein hydrolysate analysis, and quality control applications.

Amino acids naturally exist as zwitterions. Under low-pH conditions, they carry a net positive charge and bind strongly to negatively charged ion-exchange sites on the polymeric resin, while most matrix components elute in the void volume. Selective elution is achieved by gradually increasing pH and salt concentration, causing amino acids to dissociate from the stationary phase in a highly predictable manner.

The elution order generally follows the amino acids’ isoelectric points—acidic species elute first, followed by neutral and basic. Because the separation and subsequent post-column derivatization occur free from interfering contaminants, ion-exchange methods using Concise Separations columns consistently produce highly reproducible chromatograms suitable for precise quantitative analysis.

Key Definitions ▸
Ion-Exchange Chromatography (IEC)
A separation technique in which charged analytes interact with oppositely charged sites on a stationary phase. IEC is the gold standard for amino acid analysis due to its high reproducibility and matrix independence.
Zwitterion
A molecule with both positive and negative charges. Amino acids behave as zwitterions, carrying a net positive charge at low pH, allowing them to bind strongly to negatively charged ion-exchange sites.
Isoelectric Point (pI)
The pH at which an amino acid carries no net charge. During IEC, amino acids elute in an order generally correlated with their isoelectric points—acidic first, then neutral, then basic.
Post-Column Derivatization
A detection technique where amino acids react with a colorimetric or fluorometric reagent after elution, producing highly sensitive and quantifiable signals for accurate amino acid profiling.
Matrix Insensitivity
The ability of ion-exchange amino acid methods to deliver consistent retention and quantitation regardless of sample matrix, enabling reproducible comparisons across patients, batches, and hydrolysate preparations.
Frequently Asked Questions ▸

Why is ion-exchange chromatography preferred for amino acid analysis?

IEC provides highly stable retention times and quantification, regardless of the sample matrix. This consistency is essential for clinical testing, nutritional studies, and protein hydrolysate analysis where reproducibility is critical.

What is the difference between the Li+ and Na+ column formats?

Li+ columns are ideal for physiological amino acid analysis, while Na+ columns are optimized for protein hydrolysate samples. Each ion form provides different selectivity to match the sample type.

How does post-column derivatization improve amino acid detection?

After separation, amino acids react with a sensitive chromogenic or fluorogenic reagent, producing highly detectable signals and ensuring accurate quantitation even at low concentrations.