So for this aquarium project we have been doing a ton of water chemistry (over 50 hours so far). Along the way we’ve learned a number of lessons the hard way and so have written up a set of “Water Chemistry 10 Commandments”. I’m posting them here for both the current students or for anyone else doing water chemistry analysis.
1. Wear gloves! (seriously… reagents include mercury, corrosives, and carcinogens)
2. Double-check all reagents!!! For example “sulfuric acid” ≠ “sulfamic acid”. Likewise “phosphorus” ≠ “phosphate”.
3. Be sure your measurement is within the range of the test.
4. Be sure to keep track of “ppm” versus “ppb”!
5. Replace the cap of each solution immediately! Spills are expensive, hazardous, and annoying.
6. Rinse all glassware with the sample to be measured before conducting an assay
7. Always rinse everything between measurements and assays. The pH meter should be rinsed in tapwater, everything else should be rinsed in DI water.
8. Dilutions should be performed with DI water. Be sure to measure the concentration of whatever you’re testing in the DI water first so that you can subtract the background. The blank needs to be of the diluted solution as well!
9. Keep cuvettes clean! Clean before each use… wipe with a Kimwipe immediately before placing in detector.
10. If you get an anomalous measurement: do it again twice more. Sometimes things really do change but if you’ve been getting ammonia measurements between .5ppm and 1ppm for days and then all of a sudden you see 25ppm… it’s worth making absolutely sure!
Jonathan Eisen's Lab 