Solvent is refluxed from a round-bottomed flask upward into a condenser with a recirculating cold-water coil. Modern Soxhlets use sophisticated blown glass condensers and organic solvents in this "continuous" extraction method ( Figure 2). Archeological evidence from Mesopotamia places the use of a Soxhlet-like device that utilized hot water at ~3,500 BC 1,2. Soxhlet extraction is likely the oldest form of organic matter extraction. Red stars reflect those that are not accurate indicating that the instrument requires corrective maintenance. Green stars represent standards that are accurate. Each star is a weekly measurement of the chemical standard. The dashed line represents a 1:1 relationship between the accepted and measured (on the instrument) value of a variable. Schematic depicting how chemical standard tracks the performance of an instrument through time. In these circumstances, a Soxhlet extraction is used.įigure 1. The Accelerated Solvent Extraction (Dionex) and sonication extractions are not appropriate for the extraction of such large sediment volumes. Therefore, these compounds need to be extracted from natural samples, and because of the large volumes of standards required, large volumes of sediment need to be extracted. However, some compounds that occur in nature and that are relevant to paleoclimatic studies have not yet been isolated and purified for purchase. Many chemical standards can be purchased from retail scientific companies, like Sigma-Aldrich and Fisher. Because standards must test the performance of instruments over a long period of time, large volumes of the standards are often required. Source: Laboratory of Jeff Salacup - University of Massachusetts AmherstĮvery lab needs standards that track the performance, accuracy, and precision of its instruments over time to ensure a measurement made today is the same as a measurement made a year from now ( Figure 1).
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