Question

Lithium can be measured in blood serum by flame atomic emission using a standard addition method. 100 uL of serum is diluted to 100 mL and produces an emission signal of 5.7 arbitrary units. To a second 100 uL of serum is added 10 uL of 0.01M LiNO3 and dilution again to 1.00 mL, yielding a signal of 15.6 units. What is the litium concentration (ppm) in the serum?

It says the answer is 4.0 ppm, but I have no idea how to solve these types of problems.

Answer 1