Microwave-assisted sample decomposition in flow analysis Review Article

Digestion is the most demanding step in sample preparation, and its aim is to break the sample into more simple constituents with the aid of time, heat and reagents using different devices. Microwave heating emerged in the analytical field to dramatically improve the conventional wet digestion procedures with conductive heating that took several hours and reduced them to minutes in many cases. Additionally, the development of on-line microwave systems has proved them to be simple, relatively safe to use, provide a decrease in the blank values, reduce the contamination risk when completely closed systems are used, applicable to samples of different natures and completely fit for automation. The automated procedures developed so far enable on-line coupling to powerful determination methods such as flame, hydride generation and electrothermal atomic absorption spectrometry, inductively coupled plasma atomic emission spectrometry and electroanalytical methods or to hybrid techniques such as liquid chromatography–atomic absorption spectrometry or liquid chromatography–atomic emission–mass spectrometry, which have widened the application field to speciation studies. The most recent advances in flow injection–microwave sample treatment for the determination of different chemical species by these techniques will be outlined in this review.