Green extraction method: Microwave-assisted water extraction followed by HILIC-HRMS analysis for the characterization of the polar metabolome in plants

Abstract Background: Hydrophilic compounds, such as amino-acids, organic acids and sugars among others, are present in large amounts in plant cells. Analysis and quantification of these major hydrophilic compounds is particularly relevant in plant sciences since they greatly impact the quality of plant-derived products and plant-pathogen relationship. Our objective was to develop and validate a complete analysis workflow combining microwave-assisted extraction (MAE) and hydrophilic interaction liquid chromatography coupled to high resolution mass spectrometry (HILIC-HRMS) for quantitative analysis of these hydrophilic compounds in plant tissues. Results: Water-based Ultrasound-assisted extraction (UAE) and microwave-assisted extraction (MAE) methods for hydrophilic compounds were compared using HILIC-HRMS. The newly-developed method involved 20 s MAE extraction time followed by a 10 min HILIC-HRMS analysis. This bioanalytical method was validated for 24 polar metabolites, including amino-acids, organic acids and sugars, to ensure the reliability of analytical results: selectivity, limits of detection and quantification, calibration range and precision. Depending on the compounds, quantification limit was as low as 0.10 mM up to 4.50 mM. Conclusions: A method involving water-based MAE extraction coupled to HILIC-HRMS was developed for the relative quantification of free amino acids, organic acids and sugars in plant tissues. This method is amenable for high throughput analysis of major polar metabolites from small amounts of plant material.