In clinical applications, the unit parts per million (ppm) is used to express very small concentrations of solute, where 1 ppm is equivalent to 1 mg of solute per 1 L of solution. Calculate the concentration in parts per million for each of the following solutions.
a) There are 41 µg of calcium in a total volume of 69 mL.
b) There is 0.91 mg of caffeine in a total volume of 131 mL.
c) There is 0.51 mg of trace particles in a total volume of 99 dL solution.