Calculate concentrations of each of three elements in the mixture:

A mixture of U, Mg and Al was separated by paper chromatography and then quantitatively determined by spectrophotometry.  100 ppm standards of each of these were prepared and reacted with oxine for U, magneson for Mg, aluminon for Al giving absorbance values 0.85, 0.80, 0.65 correspondingly. Spot areas of paper chromatogram were cut, dissolved and their absorbances were found to be 0.39 for U, 0.42 for Mg and 0.53 for Al. Calculate concentrations of each of three elements in the mixture.

Answer:

100 ppm standards of each of U, Mg and Al display absorbances of 0.85, 0.80 and 0.65, respectively. Let's assume absorbance for unknown mixture, concentration for different elements can be calculated as follows:

Concentration of U   =   0.39×100/0.85   =            45.9 ppm

Concentration of Mg =   0.42×100/0.80 =             52.5 ppm

Concentration of Al   =   0. 53×100/0.65 =           81.5 ppm