Chemistry Of Api Test Kits

[Bignose]

If it is a post by a confirmed API rep, go ahead and make the link. Links to outside sites, including other forums, is okay if we don't have the knowledge on this site. We just don't want people linking to things on other sites that are also on this site, because we'd like them to link to this site first.

And, you're correct on why it is about a year -- it had to do with typical uses. I would guess that the 1 year is based on weekly testing. Now, if you only open the bottle once a month, you can probably get more than just 1 year out of it. The idea is that ever time you open it, new air gets in with will react with the reagents in the bottle, even though it is a small volume of air. The same thing has to be done in chemistry labs at universities and similar -- you mark the date(s) when you open the bottle, especially if the stuff in the bottle can degrade or react with components in the air.

It isn't anywhere on the pack, the bottle or the instruction leaflet. I'd never come across it before until I was told by someone who works for the company.

I've just checked the post on the other forum, and the person who works for the company said - API recommend that you don't keep the kit open for more than a year, even if it is still within the expiry date.
I would give a link to the post, but linking to other forums isn't allowed.

 

[Essjay]

Link removed as the thread no longer exists - it was removed when the site was "tidied up" removing old threads.

 

[TwoTankAmin]

 

 

[TwoTankAmin]

I am in a fun mood so I thought it would be neat to play a game off connect the dots.
 
Dot One--
 

The Direct Nesslerization Method
Reference: ASTM D 1426-08, Ammonia Nitrogen in Water, Test Method A. APHA Standard Methods, 18th ed., Method 4500-NH3 C (1992).
 
The test kits employing the well-established Nessler reagent* to determine ammonia concentrations are applicable to drinking water, clean surface water, good-quality nitrified wastewater effluent, and seawater. In some waters, calcium and magnesium concentrations can cause cloudiness of the reagent. Adding a few drops of stabilizer solution (Rochelle Salt) will prevent this cloudiness. References recommend distilling samples prior to analysis. Results are expressed as ppm (mg/L) ammonia-nitrogen, NH3-N.
Shelf-life: although the Nessler reagent is stable, its high alkali content attacks the glass ampoule. The resulting precipitate interferes with color comparison. We recommend stocking quantities of CHEMets® and VACUettes® ampoules that will be used within five months. A two-month supply of Vacu-vials ampoules is suggested. Refrigeration will dramatically extend the shelf-life of these products.
*Contains mercury. Dispose according to local, state or federal laws.

 
So That test, which is no used to any great extent in the hobby today since it produces a toxic residue- i.e. mercury, gives a reading for ammonia only in the form of NH3. It doesn't measure NH4 or total ammonia (the total of both NH3 and NH4). 
 
There is an alternative test that is now quite popular.
 
Dot Two--
 

The Salicylate Method
References: Krom, Michael D., Spectrophotometric Determination of Ammonia: A Study of a Modified Berthelot Reduction Using Salicylate and Dichloroisocyanurate, The Analyst, V105, pp. 305-316, 1980.
 
In the ammonia test method that employs the Salicylate chemistry, free ammonia reacts with hypochlorite to form monochloramine. Monochloramine reacts with salicylate, in the presence of sodium nitro-ferricyanide, to form 5-aminosalicylate, a green-colored complex. This test method measures free ammonia and monochloramine. Results are expressed in ppm (mg/L) ammonia- nitrogen, NH3-N.
The Salicylate Method offers sensitivity similar to the Nesslerization Method and there is no generation of mercury-containing waste.

 
So, this type of test also reads ammonia as NH3 and not NH4 or total ammonia.
 
Dot Three--
 
If one knows the total ammonia (NH3 + NH4) present, one can use the pH and the temperature of the water to calculate the amount of HH3 in the Total. Reversing the calculation is possible, as long as one knows the pH and the temperature of the water
 
One of the more popular test kits for testing ammonia on this and other sites is the one made by API.
 
Dot four--  
 
"AMMONIA (NH3/NH4+) TEST KIT INSTRUCTIONS
 

Testing Tips
This salicylate-based ammonia test kit reads the total ammonia level in parts per million (ppm) which are equivalent to milligrams per liter (mg/L) from 0 - 8.0 ppm (mg/L)."
From the API FW Ammonia test kit instructions http/www.apifishcare.com/pdf/Ammonia_Test_Kit_LR8600_Insert.pdf )
 
Dot Five--

?
 
Oops.   How does an API, or similar, hobby kit give a reading for something that type of test does not measure and which seems can not be acurately converted from what it does measure without knowing the pH and temperature??
 
I have no clue, do you know?

 

 

[daizeUK]

Not sure if this will answer your question but I can quote from an email I received from API when I directly asked them about something similar.
 
 
Our liquid two bottle API Ammonia Test is based on the Salicylate Method. A water sample is placed in the test tube to the line (5ml). Then 8 drops from each of the two bottles are added to the test tube and a series of chemical reactions occur within 5 minutes.
The first reaction is the ammonia contained in the water sample combines with chlorine to form monochloramine.
Monochloramine reacts with salicylate to form 5-aminosalicylate.
Then the 5-aminosalicylate is oxidized in the presence of sodium nitroprusside working as a catalyst to form a blue colour which is masked by the yellow colour from any excess reagent present which produces a green-coloured solution in the test tube.
At 5 minutes the intensity of the green colour is compared to colour chart included with the API Ammonia Test Kit to identify the level of ammonia present in the water sample being tested. If no ammonia is present no blue colour is developed and the sample is then yellow, indicating zero ammonia. Identifying the ammonia to the colour chart is referred to as a colour comparative test where the closest match indicates the level of ammonia in the water sample being tested. It is quite common to have a colour that is not a perfect match but between two colours on the chart, in this case the colour that is closest indicates the ammonia level.
The API Ammonia Test Kit reads total ammonia nitrogen (TAN). TAN is a combination of ammonia (NH3) and ammonium (NH4+). The top reading given in our colour chart is 8 ppm (mg/L). This indicates that the sample being tested is 8ppm (mg/L) or higher. For example a water sample containing 12 ppm (mg/L) would read as 8 ppm (mg/L) as this is the top of the colour scale provided.
 
[Daize] I have heard of lots of other people who have the same problem with this particular product and one in particular suggests that the problem is because the API ammonia test kit can't read low concentrations of NH4:
"Be advised, if you do use this product and an API test kit -- the API test kit does not test for lower levels of NH4, only NH3, so your results on that test might show lower than what is actually present. This problem does not exist for kits from Nutrifin or other tests that specifically test for NH3/NH4." - by reviewer tsu on Amazon.com ( http/www.amazon.com/DrTims-Aquatics-Ammonium-chloride-Aquarium/dp/B006MP4QG6 )
Can you advise me if this statement is correct and the API kit is unable to read low levels of NH4? Otherwise do you know of any other reason why the API test kit might be showing a reading of 1ppm for an ammonia-nitrogen concentration of 2mg/L?
[API] Thank you for that link - it is very interesting. No, the statement about the test not being able to detect NH4 at low levels but only NH3, and thus giving a false low result is not correct, because during the test all ammonia (NH3) is converted to ammonium (NH4) anyway before the result is read. (It also isn't biologically possible to cycle a tank in 5 days, as the same person says further on in the review!). I have not read that idea before, so thank you for bringing it to my attention. It is actually more common to read the reverse statement on the internet - that API ammonia tests read too high at low levels of ammonia and give a false high result; I know of several places where that is written. Test kits probably generate more questions/complaints than any other category of products that I deal with for Mars Fishcare, but there are no consistent themes - for example, the last ammonia test query I dealt with was the exact reverse of yours (the kit was claimed to be reading too high). Similarly, the other week I had one person complain that the API nitrate kit never read the same as the Tetra version, and a couple of days later a different person remarked to me how impressed he was that the API nitrate kit always read the same as the Tetra version!

 

[TwoTankAmin]

Let me ask this another way.
 
What does a salicylate ammonia test measure?
 
NH3?
NH4=?
TAN?
As Ions or as Nitrogen?
 
Then, why do some tests only take 5 minutes while others 15 to 30?
 
Can the salicylate method be used to obtain different results based on the use of different reagents combinations or other methodologies? For example can it be used to read either NH3 or NH4+.
 
These are meant to be generic questions rather than brand specific.
 
As I stated above, I no longer have any idea and I am having a heck of a time time finding something I trust. Where are the chemistry folks when we need them?

 

[Blobfish]

Out of interest I tested one of my tanks yesterday with an API kit dated 2008 and a brand new, unopened kit.  The only reading that was different was the pH.  The old kit gave a reading of 6.8 and the new one said 7.

 

[TwoTankAmin]

And here is my question re what blob reported. Which of the two readings was correct? Or was neither one correct? How can we know?
 
I do have my answer to what the salycilate kits measure- its total ammonia. They just have one use the normal formulas to calculate how much is in either form.

 

[Blobfish]

And here is my question re what blob reported. Which of the two readings was correct? Or was neither one correct? How can we know?

 
An interesting question.  With regards to the ammonia, nitrite and nitrate readings, they were what I expected (0,0,10) them to be.  The pH is more interesting because usually that tank would read 7.4 but I added quite a bit of bog wood a couple of days ago.  So that both tests are indicating a drop in pH shows me that they are reading correctly-ish but which to believe I'm not sure and I would like to know as not all the fish in there will be keen on acidic water .. I don't know how to figure out which is correct.