Flame photometry

Instrumental Techniques
In classical analysis, the signal depends on the chemical properties of the sample: a reagent reacts completely with the analyte, and the relationship between the measured signal and the analyte concentration is determined by chemical stoichioimetry. In
Instrumental analysis, some physical property of the sample is measured, such as the electrical potential difference between two electrodes immersed in a solution of the sample, or the ability of the sample to absorb light.
Classical methods are most useful for accurate and precise measurements of analyte
concentrations at the 0.1% level or higher. On the other hand, some specialized instrumental techniques are capable of detecting individual atoms or molecules in a sample! Analysis at the ppm (?g/mL) and even ppb (ng/mL) level is possible.
The advantages of instrumental methods over classical methods include:
1. The ability to perform trace analysis , as we have mentioned.
2. Generally, large numbers of samples may be analyzed very quickly.
3. Many instrumental methods can be automated.
4. Most instrumental methods are multi-channel techniques (we will discuss these shortly).
5. Less skill and training is usually required to perform instrumental analysis than classical analysis.
Because of these advantages, instrumental methods of analysis have revolutionized the field of analytical chemistry, as well as many other scientific fields. However, they have not entirely supplanted classical analytical methods, due to the fact that the latter are generally more accurate and precise, and more suitable for the analysis of the major constituents of a chemical sample. In addition, the cost of many analytical instruments can be quite high.