Ultrasound Assistance for Improving Detection Techniques

In Chapters 2-7, we have discussed the use of US to faoilitate preliminary operations of the analytical process such as cleaning or degassing (Chapter 2) sample dissolution (Chapter 3) removal of target analytes from solids (Chapter 4) specific processes in heterogeneous solid- and gas-liquid (Chapter 5) or liquid-liquid systems (Chapter 6) or chemical reactions (Chapter 7), in increasing closeness to detection. 

This chapter deals with US assistance to operations that are even closer to the detection step such as nebulization or spray formation immediately before the insertion of sample into atomic or mass deteotors, respeotively levitation to obtain a sample droplet (usually for in situ deteotion, with or without preconcentration or previous derivatization) and electroanalytioal determinations (either to facilitate preparation of the electrode or influence the electroanalytical step itself). In nebulization and levitation, US competes — most often advantageously — with alternative ohoioes having a similar effect in electroanalytical methods, US has a characteristio effeot. Both traditional and novel detection teohniques oan therefore benefit from US assistance in some way. 

The ultrasonio devioes used to assist levitation and nebulization are typically conventional US transduoers. Their simple design and operation have facilitated the development of widely available oommeroial equipment. On the other hand, the absence of US-assisted oommeroial eleotroanalytioal cells has promoted the construction of laboratory-made units that are usually furnished with commercial probes or, less frequently, baths. 

---