Extractions of Soil Organic Matter Using High Temperature and Pressure by Way of Commercial Espresso Machine
EMSL Project ID
51702
Abstract
Soil contains one of the largest carbon pools on earth in the form of organic matter, which is a highly complex mixture. Characterization of organic matter can inform biogeochemical processes occurring in the environment, which may have substantial ecological impacts.
However, to study the organic matter in soil, it is routinely necessary to extract it and separate it from the inorganic and insoluble components of soil. These extracts are then studied by high resolution techniques, including Fourier transform mass spectrometry (FTMS) and Nuclear Magnetic Resonance (NMR), to yield powerful molecular level insights into this significant natural mixture.
Problematically, it is known that extractions are all selective (to variable degrees), and incomplete. Previous research has investigated different protocols, and our current workflows incorporate ‘soft’ extractions with water, as well as harsher extractions with organic solvents. There is a desire to move away from room temperature or chilled water extractions, as microbial activity may continue throughout these multi-hour extractions. Similarly, organic solvents are expensive and not environmentally conscious choices, and whilst they may inhibit microbial activity through their toxic nature, the resulting extract does not necessarily represent the bioavailable organic matter in soil.
Hot water extractions are known to yield richer extractions, and the microbial activity is minimized through the heat applied, but these reactions still take an hour, in which other biochemical processes may occur. Further, it is known that supercritical fluid extractions (utilizing supercritical CO2, high pressure and high temperature) can yield rich extractions, these also do not reflect bioavailable carbon, and the SFE equipment is expensive, specialized, and difficult to maintain and optimize.
Thus, we propose to perform high pressure, hot water extractions in seconds, rather than hours, using a readily available consumer appliance – an espresso machine. Espresso coffee is a rapid extraction of coffee from coffee grinds under high pressure (>12 bar) and high temperature (>90oC), yielding a high concentration extract, and these appliances have been mass produced at an affordable cost. We will optimize a protocol for soil organic matter extraction using this hardware, and compare against cold water, RT, and hot water extractions at atmospheric pressure, to investigate the selectivity and yield of extraction via these methods. The samples will be analyzed by our traditional organic matter platforms, including electrospray ionization (ESI) FTICR MS and NMR.
It is proposed that this work will result in a new, cheap, green, fast protocol to extract organic matter from soil which can be performed at specialized and general purpose labs, as well as potentially be performed in or field sampling sites, allowing for rapid extraction and characterization on-site. Further, this protocol has a marketability for public engagement and education, where we can showcase some of the important research at the lab with approachable technologies.
Project Details
Start Date
2020-10-08
End Date
2023-10-01
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members