Hanna low range nitrate accuracy, nitrite interference

[Righteous]

Anyone have any feedback or knowledge on how the new Hanna HI781 nitrate checker might be effected by nitrite (NO2), or it’s accuracy at the very low range?

@Lasse started a thread over in the Hanna instruments forum about it. I thought I might bring the topic over here to get some more input from people.

Lasse brought up the question of what NO2 interference might look like on the new checker and if there was a way to compensate for it in the reading.

I’ve been comparing readings against Salifert (which I understand is very N02 sensitive). My Salifert test will come back positive reading about 2.5ppm, whereas the Hanna reads 0.01ppm for me.

I’m dosing ammonia daily, so I wouldn’t be suprised if I have NO2, but I don’t currently have a way to test that.

My understanding is the Hanna uses a zinc reduction. With Salifert I notice there’s not residual zinc like redsea or Hanna. Is it also a zinc reduction? Might it be more Nitrite sensitive? Hanna seems to use a lot of zinc that’s filtered out prior to adding the indicator.

I also know that some people were basically using the Hanna PO4 checker with the Redsea kit. Maybe someone might have some insight from that experiment as well?

 

[Dan_P]

Anyone have any feedback or knowledge on how the new Hanna HI781 nitrate checker might be effected by nitrite (NO2), or it’s accuracy at the very low range?

@Lasse started a thread over in the Hanna instruments forum about it. I thought I might bring the topic over here to get some more input from people.

Lasse brought up the question of what NO2 interference might look like on the new checker and if there was a way to compensate for it in the reading.

I’ve been comparing readings against Salifert (which I understand is very N02 sensitive). My Salifert test will come back positive reading about 2.5ppm, whereas the Hanna reads 0.01ppm for me.

I’m dosing ammonia daily, so I wouldn’t be suprised if I have NO2, but I don’t currently have a way to test that.

My understanding is the Hanna uses a zinc reduction. With Salifert I notice there’s not residual zinc like redsea or Hanna. Is it also a zinc reduction? Might it be more Nitrite sensitive? Hanna seems to use a lot of zinc that’s filtered out prior to adding the indicator.

I also know that some people were basically using the Hanna PO4 checker with the Redsea kit. Maybe someone might have some insight from that experiment as well?

Test chemistry for nitrates is pretty much the same: reduce nitrate to nitrite and then react nitrite with organic molecules to form a colored product.

Nitrite will interfere with the nitrate Checker, causing a high reading. I think there is a way to correct for the presence of nitrite, but you will need to measure the nitrite level and you might also need to make a calibration curve for the Checker, which is easy.

 

[Righteous]

So is anyone using this new checker? Obviously nitrite interferes with it, but looking for some real world experiences people are having in comparison to other test on accuracy and sensitivity. Hanna’s marketing it as “low range” so curious if that’s holding up.

 

[Dan_P]

So is anyone using this new checker? Obviously nitrite interferes with it, but looking for some real world experiences people are having in comparison to other test on accuracy and sensitivity. Hanna’s marketing it as “low range” so curious if that’s holding up.

Nitrite interferes with all nitrate kits.

@taricha and @Rick Mathew are studying the devices for accuracy and performance. Their work has not been completed yet but maybe they can gives their first impressions.

 

[taricha]

As far as accuracy, my hanna NO3 kit seems to work as well (errors about same size) as the Red Sea nitrate pro quantified with a digital colorimeter like a hanna checker, and compared to stock solutions.
The hanna produces far more color though, so could detect lower in theory.

 

[Roosterjack]

In my opinion the biggest source for potential error is the rather cumbersome sample prep process the Hanna requires. My nitrites are never more than a few parts per billion so I don’t have it much thought As to interference.

 

[Rick Mathew]

So is anyone using this new checker? Obviously nitrite interferes with it, but looking for some real world experiences people are having in comparison to other test on accuracy and sensitivity. Hanna’s marketing it as “low range” so curious if that’s holding up.

My first round of evaluations vs prepared known standards indicated the meter was measuring slightly low. but as Dan stated I have not yet completed my full "test drive" ...I just received my second batch of reagents and have just started to dig in....I did have some issues with the filter leaking and ended up switching to my own filters...much better!...The test itself can look a bit confusing but after a few tests it is no more difficult than the Red Sea test procedure...Working to finish the evaluation soon


rick

 

[Righteous]

I did have some issues with the filter leaking

That seems to be a common issue. On mine I found out that the plastic disc inserts in the filter had been inserted wrong. They need to be facing with the circular ridges out toward the filter.

 

[blaxsun]

So is anyone using this new checker? Obviously nitrite interferes with it, but looking for some real world experiences people are having in comparison to other test on accuracy and sensitivity. Hanna’s marketing it as “low range” so curious if that’s holding up.

Yes, but I say so with the caveat that I've only run maybe a half dozen tests with it so far (both diluted and undiluted). The results are definitely more accurate, but there is a much higher margin for user error since everything has to be very precise.

And no exaggeration, this is a 15-20 minute process per test - even when you've got it down to a fine art (the results take 8min to return alone).

If you have trouble eyeballing color swatches, the digital readout is definitely the ticket. On the other hand, I was able to independently get the same approximate results with both the Salifert and Red Sea nitrate tests, and those are only 3 min/8 min tests as well.

 

[Rick Mathew]

That seems to be a common issue. On mine I found out that the plastic disc inserts in the filter had been inserted wrong. They need to be facing with the circular ridges out toward the filter.

Thanks for the heads up....I checked and they are in correctly...It looks as if it is leaking from around the thread...not sure...

 

[taricha]

so, anybody got any sodium nitrite laying around and want to tell us how much spiking tank water with 1.0ppm NO2 raises the hanna NO3 reading?

If the hanna NO3 test were 100% efficient at the step of converting NO3->NO2 before color formation, then 1ppm NO2 would raise the NO3 reading by 1.35.
If it's only 50% efficient at the NO3->NO2 step, then 1ppm NO2 gives you +2.7ppm higher NO3 reading.
Other hobby test kits are way less than 50%, more like 10% ballpark I think. (That's why tiny NO2 reads as big NO3.)

 

[Randy Holmes-Farley]

so, anybody got any sodium nitrite laying around and want to tell us how much spiking tank water with 1.0ppm NO2 raises the hanna NO3 reading?

If the hanna NO3 test were 100% efficient at the step of converting NO3->NO2 before color formation, then 1ppm NO2 would raise the NO3 reading by 1.35.
If it's only 50% efficient at the NO3->NO2 step, then 1ppm NO2 gives you +2.7ppm higher NO3 reading.
Other hobby test kits are way less than 50%, more like 10% ballpark I think. (That's why tiny NO2 reads as big NO3.)

I do not know the chemical details of the Hanna test, but with some kits such as the Salifert or the Tropic Marin (which look to use similar chemistry to the Hanna), only a small fraction (like 1%) of the nitrate is converted into nitrite for detection. The kit then multiplies the value up by a factor of 100 to get the nitrate answer. Thus, 1 ppm nitrite present in a nitrate test can read as a bit more than 100 ppm nitrate.

 

[Righteous]

I do not know the chemical details of the Hanna test, but with some kits such as the Salifert or the Tropic Marin (which look to use similar chemistry to the Hanna), only a small fraction (like 1%) of the nitrate is converted into nitrite for detection. The kit then multiplies the value up by a factor of 100 to get the nitrate answer. Thus, 1 ppm nitrite present in a nitrate test can read as a bit more than 100 ppm nitrate.

Well that explains it. Thanks Randy!

So in other words since I’m dosing ammonia I might expect to see Salifert higher than Hanna since it’s got more nitrite interference.

I‘ve got the Hanna test down to a science. It takes me 10 minutes to prepare and measure the zero, so then the rest is mostly waiting. It’s been very very consistent, so I’m impressed so far.

 

[Roosterjack]

I‘ve got the Hanna test down to a science. It takes me 10 minutes to prepare and measure the zero, so then the rest is mostly waiting. It’s been very very consistent, so I’m impressed so far.

Any tips on the filtration part? I tend to get leaks. I also wish there was a "hack" to getting the powdered reagents to pour smoothly out of the packet.

 

[Rick Mathew]

Any tips on the filtration part? I tend to get leaks. I also wish there was a "hack" to getting the powdered reagents to pour smoothly out of the packet.

I purchased my own filters (single use)...25mm .45 microns

Here is a video on opening the packets....This takes some practice but after a while is gets easy

 

[Righteous]

The discs in the filter need to be inserted with the ridges inside facing the filter. Check out this thread..


https://www.reef2reef.com/threads/hanna-low-range-nitrate-checker-issue-is-it-me.765221/post-8063614

Mine came installed the wrong way causing it to leak.

 

[Dan_P]

so, anybody got any sodium nitrite laying around and want to tell us how much spiking tank water with 1.0ppm NO2 raises the hanna NO3 reading?

If the hanna NO3 test were 100% efficient at the step of converting NO3->NO2 before color formation, then 1ppm NO2 would raise the NO3 reading by 1.35.
If it's only 50% efficient at the NO3->NO2 step, then 1ppm NO2 gives you +2.7ppm higher NO3 reading.
Other hobby test kits are way less than 50%, more like 10% ballpark I think. (That's why tiny NO2 reads as big NO3.)

I am playing with the chemistry, cutting the sample size by half, centrifuging instead of filtering and using the Hanna Cl2 Checker to measure the color intensity. The color intensity surprised me and I immediately checked my NaNO3 for the presence of NO2-. None detected.

If I get a chance this week, I will dope Instant Ocean with NaNO2 to see what happens. If I get really industrious, I will attempt to isolate the metal from reagent B to reduce NO3 to NO2 and measure the nitrite level.

 

[Righteous]

The color intensity surprised me

Hanna states that by filtering the zinc, it reduces the bleaching effect it would otherwise have on the color formation.

https://www.hannainst.com/hubfs/006-finished-content/FAQ/FAQ-HI781-Saltwater-Nitrate-LR-Rev1.pdf?hsLang=en

 

[Dan_P]

Hanna states that by filtering the zinc, it reduces the bleaching effect it would otherwise have on the color formation.

https://www.hannainst.com/hubfs/006-finished-content/FAQ/FAQ-HI781-Saltwater-Nitrate-LR-Rev1.pdf?hsLang=en

Good heads up! Thanks

 

[taricha]

Good heads up! Thanks

Dan's being modest. He was filtering zinc out of the red sea NO3 test to improve color formation at least a couple of years before hanna's kit said we should.
Sometimes I think he DIY's all his own tests, and just buys hobby kits to check his work.

The color intensity surprised me and I immediately checked my NaNO3 for the presence of NO2-. None detected.

it's an impressive amount of color, right!? And they do it with a first step dilution of 7 to 11mL.
I assume the nitrite to color step is pretty simple and efficient, with most kits turning all the NO2 into the color forming compound. Hence the supposition that the NO3->NO2 is vastly improved.