Microwave-Assisted Sample Digestion
|
"Microwave sample preparation reduces the environmental exposure as the sample retains the clean environment, excludes additional environmental sources of contamination, and makes isolation more feasible."
— Microwave-Enhanced Chemistry,
Kingston H.M., Haswell S.J. Eds. American Chemical Society, Washington D.C. 1997 |
Traditional open beaker dissolution for sample preparation is an antiquated method susceptible to biases—primarily the contamination of the sample. However, with the advent and ever-developing use of microwave energy as a heat source, the time savings and sophistication level of sample preparation approaches that of instrumental analysis.
Closed-vessel microwave decomposition offers the following benefits:
- The environment in which the reaction takes place is clean, closed, and controlled
- The amount of acid is diminished to stoichiometric quantities of the reagents, further reducing contamination
- ppb, ppt sensitivities
- Shorter reaction time and improved digestion due to higher temperatures (far above the normal boiling point of the reagents)
- Easy-to-use control software for reproducible results
- No loss of volatile elements
 |
 
|
The Ethos EZ Microwave Labstation is the ideal tool for trace and ultra-trace sample preparation. It prepares samples in less time (minutes rather than hours), uses less acid, and retains even volatile elements. Its unique design and specialized accessories give the user a completely integrated platform for clean chemistry applications.
Closed-vessel microwave digestion does not suffer from any of the cross-contamination issues typically associated with open-vessel digestion techniques. Milestone's unique, patented "vent-and-reseal" vessel design even prevents sample contamination in case of overpressurization. Samples are processed in sealed vessels made of chemically inert materials. Specialized inserts can be used to reduce the dilution factor, minimizing exposure to reagent impurities.
The Ethos EZ also has an intuitive software interface for precise temperature ramping, resulting in consistently repeatable digestions. Simply create a temperature curve, press start, and the software automatically modulates the power output, independent of the number of samples or sample size. Methods can be easily saved, retrieved, and repeated.
Improved Trace-Level Results
| Analyte | Hot Plate | Microwave | Certified Value |
|---|---|---|---|
| As | 12.3 ± 2.27 | 17.6 ± 0.9 | 17.7 ± 0.8 |
| Cd | 0.31 ± 0.09 | 0.41 ± 0.06 | 0.38 ± 0.01 |
| Cr | 68.8 ± 7.5 | 123 ± 3 | 130 ± 4 |
| Cu | 23.8 ± 2.7 | 33.5 ± 1.2 | 34.6 ± 0.7 |
| Pb | 10.8 ± 1.3 | 17.5 ± 1.1 | 18.9 ± 0.5 |
| Hg | 0.97 ± 0.14 | 1.42 ± 0.10 | 1.40 ± 0.08 |
| Ni | 63.4 ± 3.9 | 83.2 ± 3.0 | 88 ± 5 |
| Se | 1.61 ± 0.34 | 1.54 ± 0.33 | 1.57 ± 0.08 |
| Tl | 0.29 ± 0.05 | 0.63 ± 0.02 | 0.74 ± 0.05 |
| V | 65.6 ± 8.8 | 119 ± 6 | 112 ± 5 |
| Zn | 113 ± 13.5 | 102 ± 6.1 | 106 ± 3 |
More Information
To learn more about digestion, visit our microwave-enhanced sample digestion pages.
Users of our digestion labstations can further enhance their trace-level work by using microwave energy for evaporation and concentration of samples.
Clean Chemistry: Continue to trace cleaning, acid purification, sample evaporation, or vessel inserts.
General: Go to the Milestone front page, or send us an inquiry.