Plasma and determination of uranium:

Q. Define the following terms;

a)         Plasma,

b)         Spectral interference

Q. Explain the observation during AAS determination of uranium where a linear relationship is observed in the concentration range of 500 to 2000 ppm. At lower concentrations, the relationship is nonlinear which, however, becomes linear if 2000 ppm of alkali metal salt is added.

Answer:

a)         Plasma is a conducting gas that contains a large concentration of ions and/or electrons.

b)         Spectral interference is due to overlap of lines of an element in the sample matrix with that of an analyte.

Deviations from linearity at low concentrations are often because of significant ionization of the analyte. When an easily ionized element salt such as that of alkali metal is added in excess amount then the ionization of analyte is suppressed because of the electrons produced by ionization of the metal.