Question

Describe the various stages involved in the electrothermal atomisation process and the physical or chemical processes that occur in each step.

Answer 1

It provides enhanced sensitivity because the entire sample is atomized in a short period, and the average residence time of the atoms in the optical path is a second or more. A few microliters of sample are first evaporated at a low temperature and then ashed at a somewhat higher temperature in an electrically heated graphite tube or in a graphite cup. Then the current is rapidly increased to several hundred amperes, which caused the temperature to reach upto 2000 DC to 3000 DC; atomization of the sample occurs in a period of a few milliseconds to seconds.

Atomization occurs in an electrically heated graphite tube. The graphite tube is flushed with an inert gas (Ar) to prevent the formation of (non-absorbing) metal oxides

Advantages/Disadvantages/Characterstics -

Electrothermal atomizers offer the advantage of unusually high sensitivity for small volumes of sample. Typically, sample volumes between 0.5 and 10 mL are used; absolute detection limits lie in the range of 10^-10 to 10^-13 g of analyte. Furnace methods are slow-typically requiring several minutes per element. A final disadvantage is that the analytical range is low, being usually less than two orders of magnitude.

Also this includes absorption coefficient that is find using Beer lamberts law.