1. Use only clean pipets. When not in use, store in 5% nitric acid solution.
2. Before use, rinse pipets 3 times with deionized water.
3. Pour approximately 10 mL of stock solution into a 30 mL polypropylene beaker. Swirl and discard.
4. Pour approximately 30 mL of stock solution into the 30 mL polypropylene beaker.
5. Rinse the pipet 3 times with small amounts of the stock solution.
6. Pipet the designated amount of stock solution into a 1 liter volumetric flask. If the pipet is to be used again, rinse it 3 times with deionized water before proceeding to the next stock solution. If the pipet is not to be used again, rinse it 3 times with deionized water and return it to the 5% nitric acid storage solution.
7. Discard any excess stock solution. Rinse the beaker 3 times with deionized water and allow to air dry before reuse.
8. Do Not pipet any stock solution directly from its container.
9. Do Not pour an excess stock solution back into its container.
10. Do Not use any stock solution that is past its expiration date.
11. Record the date prepared, analyst initials, stock solution bottle number, and expiration date on the quality control sheets provided.
12. Use a felt tip marker and write the date prepared and the analyst initials on the bottles used to store the calibration standards.