Microwave Extraction Gives You Better Data
Thanks to a combination of higher extraction temperatures, closed vessels, magnetic stirring, homogeneity of the microwave field, and precise computer control, users of microwave extraction can expect a better quality of data. Closed-vessel microwave heating allows organic solvents to be heated to 2–3 times their atmospheric boiling points. The reflux action that occurs during microwave heating brings the sample in contact with fresh solvent, and magnetic stirring promotes interaction between solvent and solute, helping to liberate the solute from the matrix. These combined effects lead to more accurate, more reproducible results.
For example:
Microwave Extraction of Aldrine
From Soil: Without stirring 90% recovery — With stirring 100% recovery
From Sand: Without stirring 86% recovery — With stirring 100% recovery
Extraction of Irgonox 1076 from Low Density Polyethylene
Soxhlet = 294 ± 15 ug/g
Microwave extraction = 305 ± 5 ug/g
The homogeneity of the microwave field and the precision of the temperature control are also key elements in microwave extraction. These two elements affect microwave extractions the same way they affect GC or GC/MS analysis. In GC analysis, if the heating of the column is not uniform or consistent, then there will be inconsistent peak shapes, which will lead to poor precision. In microwave extraction, if the microwave field is not homogeneous, then the samples will heat at different rates and the extraction temperature will not be uniform, again leading to poor precision.
The Ethos Extraction System contains a unique microwave diffusion system to ensure uniform heating of all samples. The heating is controlled using a PID algorithm and a graphical interface that allows heating profiles to be set similar to GC or GC/MS instrumentation.
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