Automated Amino Acid Analyzer

What is the Automated Amino Acid Analyzer?

An automated amino acid analyzer hydrolyses a protein sample and quantifies the released amino acids by ion exchange or reversed-phase separation with post-column or pre-column derivatisation. It gives composition in residues per molecule for identity and comparability testing.

Overview

The analyzer automates hydrolysis, injection, separation and detection. Samples are hydrolysed with hydrochloric acid at about 110 °C for 20–24 hours under vacuum or nitrogen, then dried and dissolved in a loading buffer. Amino acids are separated on an ion exchange column with a stepped pH and ionic strength gradient, or on a reversed-phase column after derivatisation with ortho-phthalaldehyde, ninhydrin or a fluorescent tag. Detection is by absorbance or fluorescence, and results are reported as mole percent or residues per molecule. Typical run time is 60–120 minutes for a standard protein hydrolysate, with detection limits in the low picomole range. The instrument can also be used for physiological fluid amino acid profiling and for feed and food protein composition analysis.

How does it work?

Protein analyzers apply a physical or chemical measurement that responds to a specific property of the molecule. Amino acid analysis hydrolyses the protein and separates the released amino acids by ion exchange or reversed-phase chromatography with ninhydrin or fluorescence detection, giving composition in residues per molecule. Edman degradation removes one amino acid at a time from the N-terminus by phenylisothiocyanate chemistry and identifies each derivative chromatographically, giving the first 20–50 residues. Circular dichroism measures the difference in absorption of left- and right-circularly polarised light, and the far-UV spectrum reports alpha helix, beta sheet and random coil content. Thermal shift assays use a fluorescent dye that reports unfolding as temperature rises, giving a melting temperature that shifts when a ligand binds. Surface plasmon resonance detects mass binding at a sensor surface in real time, yielding association and dissociation rate constants.

What are the key features?

• Automated hydrolysis, derivatisation, separation and detection
• Ion exchange or reversed-phase column chemistries available
• Detection limits in the low picomole range
• Composition reported as mole percent or residues per molecule
• Physiological fluid and hydrolysate methods supported
• Ninhydrin, ortho-phthalaldehyde or fluorescent derivatisation options

What are the technical specifications?

A typical automated amino acid analyzer configuration offers detection limit of approx. 5–50 pmol per amino acid, separation of Ion exchange or reversed-phase column, detection of Visible absorbance or fluorescence, run time of approx. 60–120 min per sample, hydrolysis condition of 6 mol/L HCl at approx. 110 °C for 20–24 h and sample volume of 10–100 µL. Values are indicative of the product class; the exact figures for each configuration are confirmed on the quotation and the calibration documents supplied with the instrument.

Which applications is it used for?

The Automated Amino Acid Analyzer is used in protein identity and composition testing, peptide and hydrolysate amino acid profiling, feed and food protein composition analysis and physiological amino acid measurement. Across the wider Protein Analyzers class, laboratories also deploy it for recombinant protein characterisation, biosimilar comparability studies and protein structure and folding research.

Which standards and certifications apply?

Relevant standards and methods include USP <1057>, Ph. Eur. 2.2.56, Ph. Eur. 2.2.25, ISO 17025, IEC 61010-1 and 21 CFR Part 11. Certification candidates for this model are CE, ISO 9001 manufacturing and IEC 61010-1 safety; each is to be confirmed for the specific configuration before shipment, and certificates are supplied only where they have been issued.

Sample purity and buffer composition dominate results, so prepare proteins in volatile, low-absorbing buffers for circular dichroism and avoid detergents and reducing agents that absorb in the far UV. Amino acid analysis needs complete hydrolysis, so ampoule sealing, vacuum and hydrolysis time must be controlled. Surface plasmon resonance sensors are sensitive to buffer refractive index differences, so running buffer and sample buffer should match and a reference channel should be included. Thermal shift assays need consistent dye concentration and controlled heating rates. Verify performance periodically with a reference protein such as bovine serum albumin or lysozyme, keep maintenance and calibration records, and store raw data, since circular dichroism and biosensor results are often re-analysed after method changes.

How do I select the right Automated Amino Acid Analyzer?

Select an amino acid analyzer when protein composition is reported as part of identity, comparability or nutritional testing. Specify detection limit, separation chemistry, derivatisation reagent, hydrolysis method, gradient capability and whether the software supports validated composition reports.

How does it compare with other Protein Analyzers variants?

Choose the analyzer that measures the property you must document. For composition or identity of a purified protein, amino acid analysis gives a quantitative profile; Edman sequencing provides N-terminal sequence but needs a pure, unblocked sample. Circular dichroism is the standard method for secondary structure comparison between batches and for folding studies, and it needs only 0.2–0.5 mg/mL in a low-absorbing buffer. Thermal shift assays screen buffer conditions and ligand binding quickly in 96-well format, making them useful early in development. Surface plasmon resonance quantifies affinity and kinetics, and it demands careful immobilisation chemistry and reference channel design. Compare sample consumption, sensitivity, throughput, buffer tolerance, temperature control and whether the software can export raw traces for independent analysis.