You have been asked to analyze some mineral water for magnesium by standard addition using atomic absorption (AAS). You are given 100.0 ml volumetric flasks and 1.000 ml volumetric pipettes. The mineral water has a stated value of 20 ppm Magnesium. The maximum linear reading of the AAS system is 0.300 absorbance units which occurs at 0.600 ppm of Mg.
Design a standard addition experiment using 5 flasks similar to that illustrated in Figure 5-7 of Harris. You have a 10.00 ppm stock solution of Mg. Include the following:
a. Specify the volume of mineral water to add to each of the five flasks.
b. Specify the volume of stock magnesium solution in each flask.
c. Assuming the "true" value for Mg in the mineral water is 18 ppm compute the final concentration of magnesium in each of the flasks.
d. Verify that no solution exceeds the linear range. You may do this by computing the expected absorbance of each solution from the data provided.
e. What mass of magnesium do you need to make 1.000 L of 10.00 ppm stock solution.
f. Incorporate items a - c into a short written procedure that you believe someone else could follow in the lab.