Hanna checker for Nitrate update

Scubajoe1

New member
So I spoke to the folks at Hanna today and asked...


Hi there, I am a chemist and an avid marine aquarium enthusiast. I was curious as to why Hanna has not come out with a nitrate marine test kit. I have made a standard curve in my lab for nitrates at 0,1,2,3,4,5 and 10 ppm. From this curve I am able to elucidate the nitrate concentration for my reef aquarium by running the sample through a UV spectrometer and getting an absorbance reading. It seems the chemistry is already established for the reaction and there is a HUGE market value for a digital test kit for nitrate. I use the Hanna checkers for all my other assays and was wondering why the nitrate test kit has not been introduced. Can you please forward this to your R&D department for a possible explanation and suggestion.

They quickly replied with...

Thank you for your input regarding a Nitrate Checker HC. It would not be a stretch for us to offer a Checker HC for Nitrate testing since we currently offer the HI96728 portable version. All of the Hanna Checkers are based on previous versions of our portable colorimeter line. The current portables use a tungsten lamp with a narrow band interference filter that excluded all other wavelengths except the one of interest. The previous versions used an LED at a specific wavelength as a light source. The majority of the Checker HC's are using an LED as a light source.

The portable meter for nitrate is using 525 nm which we have an LED for, so from a mechanical standpoint there are no issues. From a chemistry standpoint the cadmium reduction method has two issues:
There is a chloride interference above 100 mg/L. This would seem to be overcome if the curve is developed with standards prepared in artificial seawater.
The method is very sensitive to how the sample is mixed. This is a bit of challenge. In order to get consistent results an SOP would have to be developed in which the mixing procedure can be standardized and repeatable. It might have to include the use of a magnetic stirrer.
The above are what I believe to be the reasons that we have not moved forward with a Nitrate Checker. I will have to confirm with the R&D Department.

Out of curiosity, are you using a chemical method when doing the absorbance measurement in the UV range? I know that in process measurements of nitrate at a wastewater plant a UV based sensor (210 nm) is used in situ. There is no chemistry so I want to make sure that this is the technology that you are referring to. If it is not and you are using a chemical method then any information about the method would be useful.

Lastly, As we have the alkalinity Checker for saltwater aquariums, I am curious if we should offer a unit that displays in dKH as opposed to calcium carbonate. It seems that in the forums dKH is more common. Since it is only a change in programming it would be relatively easy to do as well.

If I find out more information then I will forward on to you as well.

Sincerely,

Paul Fabsits
VP of Product Marketing
Hanna Instruments


Hello Paul,
Thanks for getting back to me so quickly. I think the hanna alkalinity checker is fine"¦.similar to the phosphorus one we just have to multiply or divide by a constant. Ideally the phosphorus checker should measure phosphate instead of phosphorus because that's what we are interested in but like I said not a deal breaker.

In regards to the nitrate test I currently use the chemistry in the red sea test kit and do make the standards in salt water. I then tested a standard I made against the standard curve and come out pretty close. I did not need a stir bar"¦.I mix 5 drops and shake for 15 seconds, add one scup of reagent two and shake for a minute and then one scoop of reagent three and shake for 15 seconds. Then you wait 9 minutes and read. I did find that I had to filter the sample through a 0.22 or 0.4 micron filter to obtain the best reprducible results.

I would also maybe make a high range and a more accurate low range meter as well.


Hope this information helps.


Joe

So we will see what comes next
 
A digital nitrate kit would be great. :celeb3:

I'm colorblind, so I "recruit" my kids to help. Life would be much easier with a digital checker.
 
Lastly, As we have the alkalinity Checker for saltwater aquariums, I am curious if we should offer a unit that displays in dKH as opposed to calcium carbonate. It seems that in the forums dKH is more common. Since it is only a change in programming it would be relatively easy to do as well.

I think a lot of people who are not chemists, like me, would prefer the display in dKH.
 
Nitrate tester would be nice the alk they have is fairly close but the ca tester have found to be off quite a bit as compared to red sea wonder why
 
Nitrate tester would be nice the alk they have is fairly close but the ca tester have found to be off quite a bit as compared to red sea wonder why

I think part of the problem is trying to draw 1/10 ml of sample accurately, is that like 1 and 1/2 drops ? 1 drop ? 2 drops ? :lolspin: it's going to make a big difference in the results...
 
Nitrate tester would be nice the alk they have is fairly close but the ca tester have found to be off quite a bit as compared to red sea wonder why


Not quite sure why it's off unless that battery needs changing. I made a 400 ppm solution of Ca in the lab, measured it with the Hanna checker and here was my result.
396_zpsqvtqnvvs.jpg


Where are you located? I could always mail you a Ca standard and you can see what you get.

I test with my standard every month or so and it's always dead on.
 
I think part of the problem is trying to draw 1/10 ml of sample accurately, is that like 1 and 1/2 drops ? 1 drop ? 2 drops ? :lolspin: it's going to make a big difference in the results...

I have to agree with that statement. I actually use an adjustable 100 uL pipette to measure the amount. You can maybe find a 100 uL syringe online and that would ensure you get an accurate amount of tank water to test.
 
Not quite sure why it's off unless that battery needs changing. I made a 400 ppm solution of Ca in the lab, measured it with the Hanna checker and here was my result.
396_zpsqvtqnvvs.jpg


Where are you located? I could always mail you a Ca standard and you can see what you get.

I test with my standard every month or so and it's always dead on.

I am in chico, california and it is a new battery. Could be the testing procedure maybe i am doing it incorrectly i dont know. I wish they would include a cal fluid
 
How much are you off by? with the syringe they supply I would imagine you would have to be within 10% or less.
 
Ok i think i have fig it out. It has been how i have been running the tests. This eve i did alk and ca with my red sea got alk at 11 and ca at 430. I just ran these with my hanna meters making sure i followed the steps in the right order and correctly alk came in at 11.2 and ca at 432. Had to be me and the way i was doing it
 
How much are you off by? with the syringe they supply I would imagine you would have to be within 10% or less.

Hi Joe, although the alk checker never failed me, I've never had luck with the green phos or the red ca checker, the HI 93713 portable worked well for me, and i actually use the 25-pack reagent for the small checker, to avoid buying 100-pack or 300-pack a time.

With the HI736 green phos i got 0 to 60 in 3-5 consecutive tests, my guess is the noise level drawns the signal.

With the ca checker, i got anywhere between 420 to 480 in 3-5 consecutive tests, i quit testing it since that. I do use high grade distilled water, people should beware 1ppm Ca in your "water" will show up as 100ppm extra in your testing result. And I do use a 100u pipette. I've contacted hanna to check if I can add that liquid AFTER I mix distilled water and tank water, they couldn't confirm and refused to test the alternative procedure i suggested, which would greatly improve the accuracy: mix 10ml tank water with distilled to make 1L, and take 10ml of that 1L to test.

basically i believe the ca checker test procedure is fundamentally flawed for 3 reasons:
1. diluting sample under test by 100 times magnifies any interference by 100 times
2. diluting x100 at such tiny volume as 0.1ml in 10ml doesn't really help, doing 10ml in 1L would make at least the proportion much more accurate, if hanna can actually confirm a slightly modified procedure, or if they agree to sell the reagent cheap in gallons then the current procedure is fine too
3. diluent water purity too critical, as Ca in it gets magnified by 100 times, yea i know it's good business selling water at $20 a small bottle but people are simply not buying it, and often times home made RODI is not good enough for this task
 
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wondering if you guys tried 3-5 consecutive tests in a row? I always do that with whatever testing product first time i open it, while most of them are ok with acceptable consistency, i never got hanna hi736 low phos and hi758 ca to give me any consistency i can swallow.
 
I have done maybe 3 in a row and get fairly reproducible results. One thing you need to make sure is that the cuvette is wiped of all fingerprints. This is especially critical for the phosphorus or phosphate test. I have also measure before got a strangely high reading and then washed out the vial with soap and winded with RO water.

Also I would just check the RO water alone and make sure that gives you a 0 reading.

One other thing for the phosphate and phosphorus....you need to gently turn upside down and right side up. I have seen some youtube videos where people shake the hell out of the tubes which makes lingering bubbles.

Not as critical for Ca because that changes color big time. I have seen where the Ca test also read lower than I expected and then noticed there was reagent still left in the packet. Agreed these are not the best packets for dispensing. Once I made sure I have expanded the inside corners with my finger so no reagent gets trapped then I was able to get reproducible results.
 
Maybe just my units having extra high noise background. I've been using hanna portable since 2007 and checkers as soon as available on market, with all the precautions like cleaning then never touching the vial other than at the top tip or bottom, aligning the vial the same between zeroing and testing, etc. some just work fine, and the phos and ca just don't work.

The phos checker gave me very repeatable results at PO4 > 0.5ppm, but at lower range it just generates random numbers for me, doesn't matter if you put distilled water or <0.05ppm tank water to the test. While with the Ca checker, I bought my 100u pipette just for it and used high grade pure water as diluent, it just jumps between 420 to 480 when testing tank water time and time again from the same cup. That's why I guess it's the background noise level in the circuitry.
 
When using the hanna CA unit I use a 0.5ML syringe made for insulin injection and it works well. I just prefer titration reaction type kit over the complicated hanna Calcium procedure.
 
Count me in on a Nitrate checker from them!

All I really care about is ALK, PO4, Calcium and Nitrate.

3 out of 4 covered already :)
 
When using the hanna CA unit I use a 0.5ML syringe made for insulin injection and it works well. I just prefer titration reaction type kit over the complicated hanna Calcium procedure.

Complicated? You add water and 1 ml of reagent A, take a zero reading then add 0.1 ml salt water and a packet and mix and read for the most part.
 
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