Continuous Approaches to Ultrasound-Assisted Sample Preparation

DISCRETE VERSUS CONTINUOUS APPROACHES TO ULTRASOUND-ASSISTED SAMPLE PREPARATION 

The steps involved in SP can be performed (a) in a discrete or batch manner or (b) in a continuous fashion. The most salient differenoes between the two are as follows  

In a disorete approach, the analytical system is confined in a vessel or container through the walls of which US energy is transmitted if an ultrasonic bath is used. The use of a US probe in this case can involve either to dip it into the vessel or into the transmitting liquid where the vessel is located. The complexity of the analytical system determines the type of vessel or container to be used, namely an open or closed, atmospheric pressure or pressurized device, a jacket-tailored device for maintaining the optimum temperature, etc. 

Commercial and custom equipments for ultrasound-assisted sample preparation 

The absence of commercial equipment for US-assisted sample preparation clearly reflects that the analytical chemists give little importance to this way of accelerating the operations. For this reason, most applications in this area have been developed by using standard laboratory materials such as round-bottomed flasks or even beaker or precipitation vessels. Some authors have implemented US-assisted sample preparation in commercially available cells specially designed for organic synthesis or have designed and constructed their own custom devices. 

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