High-throughput analysis of amino acids in plant materials by single quadrupole mass spectrometry

Abstract

BackgroundThe amino acid profile of plants is an important parameter in assessments of their growth potential, resource-use efficiency and/or quality as food and feed. Screening studies may involve large number of samples but the classical amino acid analysis is limited by the fact that it is very time consuming with typical chromatographic run times of 70 min or more.ResultsWe have here developed a high-throughput method for analysis of amino acid profiles in plant materials. The method combines classical protein hydrolysis and derivatization with fast separation by UHPLC and detection by a single quadrupole (QDa) mass spectrometer. The chromatographic run time is reduced to 10 min and the precision, accuracy and sensitivity of the method are in line with other recent methods utilizing advanced and more expensive mass spectrometers. The sensitivity of the method is at least a factor 10 better than that of methods relying on detection by fluorescence or UV. It is possible to downscale sample size to 20 mg without compromising reproducibility, which makes the method ideal for analysis of very small sample amounts.ConclusionThe developed method allows high-throughput analysis of amino acid profiles in plant materials. The analysis is robust and accurate as well as compatible with both free amino acids and protein hydrolysates. The QDa detector offers high sensitivity and accuracy, while at the same time being relatively simple to operate and cheap to purchase, thus significantly reducing the overall analytical costs compared to methods based on more advanced mass spectrometers.Electronic supplementary materialThe online version of this article (10.1186/s13007-018-0277-8) contains supplementary material, which is available to authorized users.

Quantification of Glutamate and Aspartate by Ultra-High Performance Liquid Chromatography

“…Disadvantages of AQC are that the emission wavelength depends on the water content of the eluent, that in solutions with a high water content significant fluorescence quenching is observed [ 26 ], and that the reagent is very expensive. More recently, derivatisation with AQC has been applied for quantification of amino acids by liquid chromatography-mass spectrometry (LC-MS) [ 27 ] and liquid chromatography-tandem mass spectrometry (LC-MS/MS) in plant material [ 28 ]. In these methods the AQC tag is used to enhance binding of the amino acids to the reversed phase column and for improvement of detection.…”

Enhancing Protein Recovery in Green Biorefineries by Lignosulfonate-Assisted Precipitation

“…Free amino acids were determined on the supernatant. The supernatant was diluted and coupled with aminoquinoline reagent (AccQ-Tag, Waters, Millford, MA, USA) according to Dahl-Lassen et al (2018). The analysis was performed with a Water's UPLC and for detection and quantification a Water's QDa single quadrupole mass spectrometer was used.…”

“…Amino acid composition of the protein concentrate was determined according to Dahl-Lassen et al (2018). In brief, after acid hydrolysis (6 M HCl with 0.1% w/v phenol, 110 • C for 24 h) samples were neutralized and coupled with aminoquinoline reagent (AccQ-Tag, Waters, Millford, MA, USA).…”

Ion-Trap Mass Spectrometric Analysis of Bisphenol A Interactions With Titanium Dioxide Nanoparticles and Milk Proteins

“…Amino acids are essential nutrients in health foods and dietary supplements that occur either in the free forms or as proteins. They can be analyzed by single-quadrupole mass spectrometry with high throughput [80]. A combined mass spectrometry-nuclear magnetic resonance approach is efficient for their qualitative and quantitative analysis, with tolerances of ±10%-20%, which correspond to European recommendations [81].…”