Evaluation of physiological amino acids profiling by tandem mass spectrometry.

Background: Nowadays, the most conventional method to quantify physiological amino acids consists in ion exchange chromatography (IEC) followed by post-column ninhydrin derivatization and UV detection at two wavelengths. Unfortunately, the technique presents some drawbacks such as long run time, large sample volume, and specific costs associated to the maintenance of a dedicated instrument. Therefore, we aimed to switch towards a mass spectrometry approach.

Methods: We have tested the aTRAQ kit for Amino Acid Analysis of Physiological Fluids (AB Sciex), affording the selective quantification of about 40 amino acids, and present here the results of our assessments.

Results: Outlined accuracy profiles for each amino acid demonstrated very reliable data. A good linearity was observed from 1 to 1,000 μmol/L. RESULTS comparison with IEC showed a right concordance. Reference intervals established were very similar to those obtained by IEC and patients suffering from inborn error of metabolism have been readily identified.

Conclusions: The present approach offers a valid alternative to the IEC method, with several advantages: lower sample volume, run time reduction, and improved specificity. However, the aTRAQ method requires minute data reviewing, expending the overall time of procedure. Finally, financial and practical considerations of both techniques have to be counterbalanced before engaging any transition.