21. Solving a chemistry problem

196. When determining potassium in a production solution by the atomic absorption method, the method of additions was used. Samples of analyzed and standard (12 µg/ml) solutions of potassium were introduced into volumetric flasks of 50 ml, diluted with water to the mark, atomic vapor was obtained, and optical density was measured at λ = 766.5 nm. The results are shown below:

Volume of solutions, ml A
analyzed standard
10 0 0.11
10 10 0.52
10 20 0.94
10 30 1.35


What is the concentration of potassium (µg/ml) in the analyzed solution?