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Back to the title topic, I probably missed it, but do we know if nitrite impacts the Hanna nitrate kit, and if so, but how much?
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isn't valid - it should always be "AND" , or the +-2% is meaningless window dressing.
That is my interpretation... .25 or below could be zeroMy understanding too, with the caveat that a meter reading of 0.25 and below means 0 ppm Is a possibility right? That’s why I am thinking in terms of LOQ.
If I get a little free time, I will look at the spectra of a Hanna test and see if there is detectable color when Hanna reads zero.
@taricha did quite a detailed look at the response of one of the Checkers and thought it look “strange” near zero.
Back in post #24 I compared how the same amount of nitrite registers as nitrate with the Hanna and Red Sea kit, assuming nitrite survives the zinc reduction step. It has a smaller impact for the Hanna test. But now I am not sure this is a valid test because of the assumption.Back to the title topic, I probably missed it, but do we know if nitrite impacts the Hanna nitrate kit, and if so, but how much?
Back in post #24 I compared how the same amount of nitrite registers as nitrate with the Hanna and Red Sea kit, assuming nitrite survives the zinc reduction step. It has a smaller impact for the Hanna test. But now I am not sure this is a valid test because of the assumption.
Since doing the above experiment I have learned that Zn metal will reduce nitrite. To correctly answer the question, I must go back and process a nitrite containing sample with the zinc reduction step intact to determine how much nitrite survives to produce a color.
Here are the results for nitrite interference for Hanna Marine Nitrate and Red Sea Nitrate Pro.Back to the title topic, I probably missed it, but do we know if nitrite impacts the Hanna nitrate kit, and if so, but how much?
Nice work Dan...looks like the measurements we take on NO3 in an established system would be very close give the additional nitrite available should be low...if I am reading this right...and it seems the Hanna method does a better job of conversion..Here are the results for nitrite interference for Hanna Marine Nitrate and Red Sea Nitrate Pro.
Nitrite interference is smaller for Hanna than Red Sea. You will note that all slopes are much less than 100.
Very nice. FYI, Hanna uses a copper-cadmium reducing agent (from their MSDS), which has been shown to quantitatively reduces nitrate to nitrite. Your experimental observations confirm this.Here are the results for nitrite interference for Hanna Marine Nitrate and Red Sea Nitrate Pro.
Nitrite interference is smaller for Hanna than Red Sea. You will note that all slopes are much less than 100.
Thanks Rick!Nice work Dan...looks like the measurements we take on NO3 in an established system would be very close give the additional nitrite available should be low...if I am reading this right...and it seems the Hanna method does a better job of conversion..
Thanks for the work...very helpful
Rick
Very nice. FYI, Hanna uses a copper-cadmium reducing agent (from their MSDS), which has been shown to quantitatively reduces nitrate to nitrite. Your experimental observations confirm this.
Very nice. FYI, Hanna uses a copper-cadmium reducing agent (from their MSDS), which has been shown to quantitatively reduces nitrate to nitrite. Your experimental observations confirm this.
Back to the title topic, I probably missed it, but do we know if nitrite impacts the Hanna nitrate kit, and if so, but how much?
Is it perhaps as simple as Hanna is using a lot of zinc to reduce the nitrate? Other tests use a lot less since theres no filtering step. With the Hanna there’s so much zinc the sample just looks grey prior to filtering.
Hanna also uses the cadmium reduction method in their 100 pack refills for their photometers (https://www.hannainst.com/hi93728-0...R0nn0VoauY50jLOeetYsD9WUU0cI060waApq5EALw_wcB). MSDS is attached.This is not correct. Here’s the actual SDS for the HI781B-0 reagent which indicates it’s zinc.
Is it perhaps as simple as Hanna is using a lot of zinc to reduce the nitrate? Other tests use a lot less since theres no filtering step. With the Hanna there’s so much zinc the sample just looks grey prior to filtering.
I pretty consistently get readings of 2ppm on Salifert while Hanna reads only 0.10ppm, so that’s an order of magnitude. This is with regular ammonia dosing.
Yes, the reductant and reduction time are both important. I think Hanna uses a longer incubation time than most tests (I thought it was 8 minutes) to ensure more complete reduction. I have attached a really nice review of assays for determination of nitrate and nitrite that goes over several dozen different assays and compares their limits of detection and interference.I do not believe that the degree of interference of nitrite with a nitrate kit like Salifert or Tropic Marin is inherent only to the nature of the reductant, but rather to what fraction of the nitrate is intended to be reduced in the time allowed for the test. That is where the multiplier on the more easily reduced nitrite comes from, since it will probably be 100% reduced instead of, say, 1% or 5%.
Thus, the exact times and concentrations of the various components that alter the fraction of nitrate reduced should be what drives the interference ratio.
I do not know exactly what factors are most important, but as you suggest, the amount of reducing agent certainly seems likely to be a big part of it.
Yes, the reductant and reduction time are both important. I think Hanna uses a longer incubation time than most tests (I thought it was 8 minutes) to ensure more complete reduction. I have attached a really nice review of assays for determination of nitrate and nitrite that goes over several dozen different assays and compares their limits of detection and interference. The review notes that among all the reductants, cadmium-copper is close to 100% efficient. The Hanna nitrate reagent 100 pack refills use cadmium-copper (HI93728-0) whereas the Hanna 25 pack refills use zinc (HI781B-0).
You're right. I had saved the MSDS a while back out of curiosity, but this is for their more advanced instrument.Just to be clear, this thread has been discussing the HI781 Hanna LR Nitrate Colorimeter. This test only uses zinc.
You are referring to the HI96728 Nitrate-Nitrogen Portable Photometer which uses that cadmium based reagent you linked. It’s a different machine and measuring procedure, so the reagents are not going to be swappable.
You're right. I had saved the MSDS a while back out of curiosity, but this is for their more advanced instrument.
Hi @LasseI´m sorry @Dan_P - but I not understand your graphs. The Hana graph more or less say that the interference is 1:1 - it means that if you have 1 ppm nitrite in the water, 0 ppm nitrate in the water and you test for nitrate - you will read 1 ppm nitrate. That´s not my experiences.
Tropic marine normal nitrite/nitrate test kit have the ratio 1:50 and the Pro version 1:100. The tests I have done indicate that Salifert is in the 1:50 range - also the Hanna checker - but I will do more tests with Hanna Checker
Sincerely Lasse