35. Solving a chemistry problem

49. Calcium concentration in blood serum was determined ionometrically. The potential of the Ca-selective electrode in the analyzed solution is 217.6 mV, and after diluting 100 µl of a standard solution containing 2000 µg/ml calcium to 2.00 ml of the analyzed solution, it becomes 226.8 mV. The slope of the electrode function with a 10-fold change in activity is 59.2/2 mV. Calculate the calcium concentration in the serum sample.
Answer: 87.1 mcg / ml.