Microwave-assisted sample digestion techniques excel in decomposing tough samples completely by raising the temperature of reagents higher than the boiling point. The key to increasing the boiling point of reagents is their entrapment in Teflon® lined close digestion vessels.
The usual digestion process starts with the samples being weighed in Teflon® liners and digestion reagents added thereafter. Current microwave digestion systems are available from various manufacturers that handle from 12 to 40 samples at a time as a batch. Weighing and adding reagents to that many samples presents a significant task for the human operator, with sample accuracy, and human safety being paramount challenges. At the end of the digestion-cycle, sample dilutions become a challenge as the liners are not transparent. Therefore, typically these samples are transferred to transparent standard flasks for post digestion sample-prep. Doubtless, this essential process of sample transfer to the flasks demands a lot of labour and care; it is time-consuming. Thus, even though the samples may be digested in under 30 min, it takes a lot longer to get the samples in a form to be available for analysis on spectroscopy instruments.
So, what is the solution? Well, automating the peripheral tasks of the Microwave Digestion process can definitely provide significant time relief with enhanced throughput and safety. The Vulcan automated workstation from Questron is an effective such time relief. Multiple reagent dispensing, sample dilutions, and sample transfers are effectively handled by this system. The system comes with racks specifically made for holding the user microwave liners so they can be easily processed. Before the actual sample digestion step, Vulcan readies the liners by adding mandated reagents, following which the vessels undergo the microwave digestion step. At the end of this, samples are brought back to Vulcan for dilutions and homogenizing without any vessel exchanges. Precise dilutions and transfers are performed with the aid of a built-in ultrasonic sensor, and a choice of built-in multiple peristaltic or syringe pump modules. For agitation of samples to facilitate mixing, short bursts of air bubbles are used by the system. Finally, prepared samples can be transferred to autosampler racks that are carried to analysis instruments.
In summary, the peripheral yet critical tasks associated with a Microware Digestion System can be easily handled by Questron’s Vulcan automation system. Not only does this significant automation yield higher accuracies and sample prep quality, but it also saves labour and promotes lab safety.