Are Elos and Salifert NH3 Tests Any Good?

[Dan_P]

I just ran tests for ammonia on ammonia chloride solutions I prepared with tap water. Both kits are advertised as being compatible with salt and fresh water.

The Elos (Expry 11-16) test was completely inert, giving no color change whatsoever for NH4Cl concencentrations from 1 to 1250 ppm.

Salifert (Expry 9-15) was only a little better. It indicated 1.5 ppm for a 16 ppm solution. At 5 ppm, there was a hint of color.

Am I missing something or could these tests really be this bad?

Dan

 

[Boomer]

Did you subtract the Chloride from NH4Cl

N = 14
H = 4 ( 4 x )1
Cl = 35.45
14 + 4 + 35.45 = 53.45 < NH4 is only 33.67 % of that 53.45

18 / 53.45 = 33.67%
33.67 % x claimed 16 ppm = 5 ppm should read

And you don't ever prepare it from TW but RO/Di or DW. Many tap water contain Chloramine.

How did you make it. You DONT take a liter of water and dump in x grams. Meaning , if I say to make a 35 ppt ( 35,000) solution. It goes like this

1 liter is 1 kg so each ml = 1 gram


1000 ml water - 35 grams of salt to be added = 965 ml of water and 35 grams of salt in 965 ml = 1 kg . You now have a solution that is 35,000 ppm.


Don't know what you did but you really messed up. That should be evident by two kits being waaaay to far off .

 

[Dan_P]

Did you subtract the Chloride from NH4Cl

N = 14
H = 4 ( 4 x )1
Cl = 35.45
14 + 4 + 35.45 = 53.45 < NH4 is only 33.67 % of that 53.45

18 / 53.45 = 33.67%
33.67 % x claimed 16 ppm = 5 ppm should read

And you don't ever prepare it from TW but RO/Di or DW. Many tap water contain Chloramine.

How did you make it. You DONT take a liter of water and dump in x grams. Meaning , if I say to make a 35 ppt ( 35,000) solution. It goes like this

1 liter is 1 kg so each ml = 1 gram


1000 ml water - 35 grams of salt to be added = 965 ml of water and 35 grams of salt in 965 ml = 1 kg . You now have a solution that is 35,000 ppm.


Don't know what you did but you really messed up. That should be evident by two kits being waaaay to far off .

I had a chuckle when you said "...but you really messed up."

Yes, i did forget to multiply the 16 ppm by the ratio of molecular weights (DUH).

Guilty, I chucked 5 g ammonium chloride into 50 mL of water, but that only makes the concentration off by about 10%. Not enough to explain 5 ppm v 1.5 ppm, but maybe the best that can be expected for this test. I will repeat the exercise with RO water, and maybe ,I still can get partial credit for this lab I will report back with my new results to correct any wrong impressions About Salifert kit.

What about Elos? That test was inert. Any ideas? Just a bad kit?

Thanks for the quick reply.

Dan

 

[Dan_P]

I just ran tests for ammonia on ammonia chloride solutions I prepared with tap water. Both kits are advertised as being compatible with salt and fresh water.

The Elos (Expry 11-16) test was completely inert, giving no color change whatsoever for NH4Cl concencentrations from 1 to 1250 ppm.

Salifert (Expry 9-15) was only a little better. It indicated 1.5 ppm for a 16 ppm solution. At 5 ppm, there was a hint of color.

Am I missing something or could these tests really be this bad?

Dan

I took the feedback and performed the analysis again. I dissolved 5 g of ammonium chloride in RO water to a volume of 50 ml. I then performed serial dilutions to obtain standard concentrations of ammonium chloride. The amount of ammonia for each standard is calculated by multiplying the ammonium chloride concentration by (17/53.5). Here are the results and picture of each test solution.

As you can see, the Salifert test still underestimates the ammonia concentration. Notice the colors do not match the chart. To check my eye sight, I diluted the samples with RO water and put them in my phosphorous ULR Hanna checker. Below is the plot of the results.

The optical density is changing in a linear fashion but the last test at 0.6 ppm really dropped off the line.

I did not retest the Elos product. It was inert either because of poor quality control or the product does not work. I am still interested in obtaining a reliable test and may repeat this analysis with API and Seachem products.

Dan

 

[Boomer]

I still think you are making errors more than likely with your DIY stds. and dilutions. Just because you have a Hanna means nothing unless it is verified against at std . You can get real stds from HACH. Look at your sheet, You show NH3 and NH4 they are not the same.

Why on earth are you using a Hanna phosphorus checker for testing ammonia ? The cell wave length and color are not the same. And when you say NH3 that is really wrong. Your are testing or giving results for total ammonia and most will be ammonium NH4+ and not ammonia NH3. NH3 is calculated as a pure function of temp and pH. The lower the pH the more N4+. Many meters and kits do idiotic things, what we call a expression. Also in kits and meters there is Ammonia-N and Ammonium-N and Ammonium and Ammonia. I think the Salifet is correct and the meter is way off. Have you called Hanna about using a phosphorus meter for testing Ammonia. When a kit or meter gives NH3 they are pretending that if all the Ammonium was converted to ammonia that how much you would get. An Alk kit for example does not give you the Alk. The reading you are getting is an expression that if you had x Alk and y Calcium that is how much calcium carbonate you could get from that Alk. Think about that. You have a glass of ultra pure water, 18.2 mega ohms add baking soda, NaHCO3, whet the hell is the calcium coming from when the expression is z Alk as CaCO3, calcium carbonate in that glass ?

I had all the Elos kits sent to ENC Labs, a certified sea water testing lab quite awhile back and they all came back with flying colors. Yes, you could have gotten a bad kit.

You may want to look at the massive book, Standard Methods for the Examination if Water and Waste Water, that gives accepted stds, to include "ammonia"

 

[Dan_P]

I still think you are making errors more than likely with your DIY stds. and dilutions. Just because you have a Hanna means nothing unless it is verified against at std . You can get real stds from HACH. Look at your sheet, You show NH3 and NH4 they are not the same.

I don't have an orthogonal method like TDS to prove my concentrations are correct, so, there is a possibility of an error. I will check out the HACH tests.

I agree with what you say about the use of the Hanna checker but possibily you misunderstood the purpose of the use. Since the color of the Salifert test solution did not vary but the intensity did, I used the Hanna checker just to confirm that the optical density was changing in a meaningful way across the samples. While I don't have proof for my ammonium chloride solution concentration, my serial dilutions were done correctly.

Why on earth are you using a Hanna phosphorus checker for testing ammonia ? The cell wave length and color are not the same.[\QUOTE]

I explained this above. The cell length is only relavent in getting enough sample between the light and the detector (Beer's law). The proper wavelength is important to maximize the sensitivity of detection. I was lucky that the wavelength used in the Phosphorous Hanna checker was absorbed enough by the test solution to provide me with some readings. If you trusted my standards, I was actually calibrating the checker .

And when you say NH3 that is really wrong. Your are testing or giving results for total ammonia and most will be ammonium NH4+ and not ammonia NH3. NH3 is calculated as a pure function of temp and pH. The lower the pH the more N4+.[\QUOTE]

Because ammonia concentration is pH dependent, the test kits add base to convert the mixture of ammonium/ammonia to all ammonia and reports total ammonia nitrogen. It is up to the user to figure out, depending on the pH of their system, whether there is an issue.

You bring up an important point. Is there sufficient base to convert 100% ammonium chloride to ammonia? I need to test the pH of the test solution to confirm it is high (pH 12 I think).

I had all the Elos kits sent to ENC Labs, a certified sea water testing lab quite awhile back and they all came back with flying colors. Yes, you could have gotten a bad kit.

OK, poor quality control then.

You may want to look at the massive book, Standard Methods for the Examination if Water and Waste Water, that gives accepted stds, to include "ammonia"

You're a pal. Thanks again for your help.

Dan

 

[Boomer]

Dan

Two things

The proper wavelength is important to maximize the sensitivity of detection. I was lucky that the wavelength used in the Phosphorous Hanna checker was absorbed enough by the test solution to provide me with some readings.

Ok, but my issue is are they correct readings, they need to be verified. Must make any stds out of DW or RO/DI not tap water.

Because ammonia concentration is pH dependent, the test kits add base to convert the mixture of ammonium/ammonia to all ammonia and reports total ammonia nitrogen.

Yes, but most kits in this hobby do not use or report NH3-N but NH3 or even NH4 as the expression, same for Nitrate and Nitrite. That N in NH3-N means you are only looking at the N concentration leaving out the MW of the H3. For example, 1ppm NH3-N x 1.2 = 1.2 ppm NH3. But this is no leaps and bounds like PO4-P, NO3-N or even NO2-N.

pH 12

The pKa is like 9.5, @ 1M in solution it is 11.6 pH

Anyway, keep up the good work as I do not do this anymore.

Glad someone is