Test kit questions

[KoiCCAPW]

Good day all,

I'm a dedicated lurker on this board and I have to say I think I've learned more here than most other boards. I hope someone here can answer my questions.

I have the Aquarium Pharmiceuticals Freshwater Master test kit. It uses 4 glass test tubes and drops to do 4 tests: Ammonia, Nitrate, Nitrite, and pH.

I read somewhere that if you use one of the test tubes for ammonia and then next time use it for one of the other tests, it could mess up the results. Even if you rinse it well. Something about residue left in the tube skewing the next test. Is this true? The instructions don't say anything about it.

Also, there is supposed to be two different types of test kits, don't remember what each is called, but how do you know which one you have? Again, mine doesn't say. I think I read one kind doesn't read correctly after you use ammonia binder in the water.

And lastly, how do you all clean the tubes? At first I was just rinsing them in tap water, but after reading the above info, I've been using dish detergent and rinsing really well. Is this necessary?

Thanks!

[bekko]

Use an ammonia salicylate test kit if you also use Amquel, ChlorAmX or another ammonia binder. In the salicylate method, the sample will be yellowish is there is no ammonia present and various shades of green if there is ammonia present.

After using ammonia binders, the nesslerization process of determining ammonia will not work. In the nesslerixation process, the sample turns various shades of reddish purple.

What you describe about residue from one test reacting with another test is possible. However, the precision of all the tests is not that great when using a color chart, color wheel, or other visual means of determining concentration. It gets the job done though and you are not concerned with deriving a value which is accurate to three decimal places. You just want to know if the water is toxic to fish. I think the inherent inaccuracies using a visual color comparison will probably make any inaccuracies associated with contamination from test tube residual inconsequential.

If you are determining concentration with a spectrophotometer instead of a color chart and need to comply with the standard methods for analysis of water and wastewater for legal reasons, then residual contamination could be a consideration.

I wouldn't use detergent to clean them until I had looked into the possibility of interference from soap residue. An acid rinse followed by at least three rinses in distilled water would be the procedure used by a certified lab or the anal retentive.

Personally, I rinse out the test tubes with tap water after use and ream them out with a paper towel when they get really grungy.

-steve hopkins

[KoiCCAPW]

Thanks Steve, I guess I'll go back to rinsing them also. I appreciate the reply, it was very helpful!

[PapaBear]

Quote: Originally Posted by bekko Use an ammonia salicylate test kit if you also use Amquel, ChlorAmX or another ammonia binder. In the salicylate method, the sample will be yellowish is there is no ammonia present and various shades of green if there is ammonia present. After using ammonia binders, the nesslerization process of determining ammonia will not work. In the nesslerixation process, the sample turns various shades of reddish purple. What you describe about residue from one test reacting with another test is possible. However, the precision of all the tests is not that great when using a color chart, color wheel, or other visual means of determining concentration. It gets the job done though and you are not concerned with deriving a value which is accurate to three decimal places. You just want to know if the water is toxic to fish. I think the inherent inaccuracies using a visual color comparison will probably make any inaccuracies associated with contamination from test tube residual inconsequential. If you are determining concentration with a spectrophotometer instead of a color chart and need to comply with the standard methods for analysis of water and wastewater for legal reasons, then residual contamination could be a consideration. I wouldn't use detergent to clean them until I had looked into the possibility of interference from soap residue. An acid rinse followed by at least three rinses in distilled water would be the procedure used by a certified lab or the anal retentive. Personally, I rinse out the test tubes with tap water after use and ream them out with a paper towel when they get really grungy. -steve hopkins

I was gonna answer, but your stole my thunder so I'll just say "ditto".