Open-Vessel Digestion
Digestion of organic samples tends to produce gaseous by-products, such as CO2 and NOx. As a result, larger sample sizes inevitably produce higher pressures inside a closed digestion vessel. Generally, no more than 1 gram of dry organic sample can be digested in a closed vessel.
Larger samples—on the order of several grams—are desirable in a variety of applications, to improve the detection limit during analysis, or to serve as a more representative portion of a large sample bulk. This is particularly true with applications such as plastics and polymers, oils, waste products, food and feed, and a variety of other highly reactive compounds.
Milestone's innovative Ethos MOD labstation allows rapid (30 minutes) digestion of up to 8 organic samples with dry weight of up to 5 grams. The unique advantage of the MOD is that it can also be utilized as a closed-vessel digestion system by adding any Milestone closed-vessel rotor, giving chemists the greatest flexibility within a single sample preparation platform. The built-in software allows the use of both open- and closed-vessel procedures.
How the Ethos MOD Works
The Ethos MOD (Microwave Open Digestion) system consists of a microwave labstation with MOD-8 rotor for processing up to eight samples simultaneously, a VAC-4000 acid scrubber module, a fully automated acid dosing system, and a color touch-screen control terminal.
Place the samples to be digested into 200 mL glass or quartz vessels, and insert them into the rotor. Then, select one of the standard programs for easy, medium difficulty, or very difficult samples—or customize the time-at-temperature profile and acid dosing parameters to create your own program, which can be stored for repeated use.
Press Start, and the labstation will automatically carry out the program, monitoring the temperature in each vessel with an infrared sensor, and continuously adjusting the microwave power output to match the desired temperature profile with great precision. The fully automated dosing system will deliver precise amounts of as many as three different reagents at specified intervals. As the digestion proceeds, the VAC-4000 acid scrubber module safely and efficiently exhausts and/or neutralizes the acid vapors produced.
SIMULTANEOUS DIGESTION OF UP TO 8 SAMPLES
The MOD-8 rotor is a specially engineered module for simultaneous open-vessel digestion of up to eight samples, in standard 200 mL glass or quartz vessels. The entire rotor is composed of ultra-pure, chemically inert PTFE and PP plastics to minimize contamination.
The individual vessels are isolated, each with its own individually connected vacuum exhaust line, so there is no cross-contamination, and Milestone's unique sealing system prohibits leaking. Each vessel is also individually connected to the automated acid dosing system, to ensure precise control over the distribution of acid to each sample. Finally, the high-efficiency VAC-4000 acid scrubber module performs exhaust and neutralization of acid vapors during the digestion run.
