TEST METER FOR TESTING NITRATES

[Rick Mathew]

So your study is based off .35 and the Red Sea kit?

Correct

 

[TheEngineer]

Good question...Not sure...what is the color of the salifert NO3 test results?...Each Hanna Meter has a specific light source and is selected based on the color of the end test solution...if the Salifert test is red you should be able to do the same thing I did with the Red Sea...You would need to run the standards and generate a regression for that specific test...hope this helps

rick

It is red based. Although thinking about this further.... it only uses 1mL of water. Diluting to 10% will probably make the readings pretty poor.

 

[Rick Mathew]

It is red based. Although thinking about this further.... it only uses 1mL of water. Diluting to 10% will probably make the readings pretty poor.

That could be the case...you could consider increasing the water sample to say 5 or so and increasing the reagents used accordingly...I am working on an Iodine Test using the Red Sea Pro Iodine kit. It only used 5 mL...So I doubled the amount to 10 and then doubled the reagents used and it gave me good results...another trick I have used is to put a spacer inside the meter holding space to be able to measure smaller quantities...as long as you don't interfere with the light source port this also works...Just some thoughts

 

[ckalupa]

Thank you

Your understanding is correct...The reading on the video is using the HI-736 Checker...The equation you plugged the "83" reading into was developed for the HI-764 Meter...This would generate a value of 4.3 as you state an "83" reading on the HI-736 would have yielded a value of about 1ppm...Each meter has its own separate regression equation...

@Rick Mathew so I don’t screw it up- what is that regression formula for the HI-764 meter?

Thanks. Will let you know how my results compare to the Red Sea and Salifert kits also

 

[Rick Mathew]

@Rick Mathew so I don’t screw it up- what is that regression formula for the HI-764 meter?

Thanks. Will let you know how my results compare to the Red Sea and Salifert kits also

Y= 0.04581221*x + 0.5017498

That would be awesome...Thanks

rick

 

[aarbutina]

Thank you sir....Based on my quick look at the salinity effect I would say your number is about right. I am doing some addition work related to salinity level and its effect on the measurement...will post it when I get it done

Great. I look forward to hearing about your additional work.

 

[ckalupa]

@Rick Mathew I did my first round of test using the ULR Nitrite meter (764). This really shows why I wanted a meter for sure! I did three tests on the same sample - The Salifert kit, the Red Sea test kit, and the Hanna method you developed using the Red Sea reagents. I will say I personally prefer the RS reagents to the Salifert as they are not as powdery and seem to level on the spoons much easier.

Here is my results (I have the same Salinity as your model)

Red Sea - I read this as being between the 10 and 20 color marks (not quite the 10 but not as dark as the 20)
Salifert - Same - read between the 5-10
Hanna method - meter read 125 and after plugging into the formula that gave me 6.22

THANK YOU again - @Rick Mathew - I will keep going on comparisons but this is a very exciting development!

 

[TheEngineer]

Did you run the Salifert test at 10x the volume? That gets really expensive to do a test, if so.

 

[ckalupa]

No. Just the 1Ml per instructions.

Just to clarify- the Salifert and RS tests I noted above were just compared to their respective color cards. I always struggle trying to quantify the colors To the charts. Especially when they are in between. Now I don’t have to.

 

[TheEngineer]

Oh, I see. I thought you put the Salifert into the Hanna checker.

 

[ckalupa]

Yeah I realized I was not clear about what I did. Would have to go through the process of establishing the curve for their test kit chemicals. And you’re right, you would only get 10 test out of the box if you made the 10 times recipe

 

[Rick Mathew]

@Rick Mathew I did my first round of test using the ULR Nitrite meter (764). This really shows why I wanted a meter for sure! I did three tests on the same sample - The Salifert kit, the Red Sea test kit, and the Hanna method you developed using the Red Sea reagents. I will say I personally prefer the RS reagents to the Salifert as they are not as powdery and seem to level on the spoons much easier.

Here is my results (I have the same Salinity as your model)

Red Sea - I read this as being between the 10 and 20 color marks (not quite the 10 but not as dark as the 20)
Salifert - Same - read between the 5-10
Hanna method - meter read 125 and after plugging into the formula that gave me 6.22

THANK YOU again - @Rick Mathew - I will keep going on comparisons but this is a very exciting development!

Awesome....I know what you mean about the color chart interpretation..can be difficult at times...The thing for me was I wanted a measurement that could provide me data that I could use to better look at cause and effect...Carbon dosing, feeding changes...or what ever, and the color charts just didn't cut it for me....Just a note...The meter only goes to 200...if you hit the wall (200), because the concentration equation is linear you can dilute the sample ...say by 1/2. Then take the reading an multiply by 2 and enter this number into the formula...but you probably already figured that out...

Thanks so much for the feedback...it is very helpful in test development to get collaboration in results...it helps to validate, refine...as well as discover errors and problems with the method...As a participant on several ASTM methods development groups this was critical to publishing a new method....along with a reliability statement this helps one to have confidence in the results....Without these we can develop "Don Quixote" methods....seems real but has no basis in reality...done it myself...lots of experience ...

Thanks again...happy for any data you can send my way

rick

 

[ckalupa]

@Rick Mathew do you know what the Hanna meter will report if above 200? Does it just say 200 or ERR? Just trying to know if I see it that I need to try the alternate test?

To keep our correlation trial relevant:

If the nitrates were above that 9.5 range (200 reading) Would you also cut the reagent chemicals used in half or still use the full dose on the 50% (5ml) test sample? Too- fill the additional 5ml with RODI water to get the 10ml for the Hanna?

 

[Rick Mathew]

@Rick Mathew do you know what the Hanna meter will report if above 200? Does it just say 200 or ERR? Just trying to know if I see it that I need to try the alternate test?

To keep our correlation trial relevant:

If the nitrates were above that 9.5 range (200 reading) Would you also cut the reagent chemicals used in half or still use the full dose on the 50% (5ml) test sample? Too- fill the additional 5ml with RODI water to get the 10ml for the Hanna?

The meter flashes 200...my procedure when it flashes 200 is I take the 10mL from the test vile and dump it into a small container and add 10 mL of the un-reacted water to it, mix and then place 10mL of the diluted solution into the measurement vile and remeasure...get the results and multiply by 2...or 3 or 4...what ever the dilution factor is....but you bring up an interesting idea...what if one doubled the initial test water volume (16mL to 32mL)...would the meter pick up the lower levels of NO3....if it worked we would have doubled the meter range...this is why collaboration is so awesome...by simply asking a question and new idea is born....I will give it a try

Thanks
rick

 

[ckalupa]

@Rick Mathew another thing we should coordinate: if we do the 50% dilution- should the baseline C1 sample also be 50% RODI?

 

[ckalupa]

@Rick Mathew

I just did a little experiment with this (Saturday, everyone sleeping in makes this easier)

I did the following:

#1
10ml test solution per the Red Sea instructions (watch for the reaction byproduct) = 82 (4.25)
10ml diluted w/ 10 ml RODI(but used 100% test sample for the C1) =39, x2=78 (4.07)

#2
16ml using the procedure as outlined = 100 (5.08)
16 ml sample (10ml test diluted with 10ml RODI) but 100% C1 sample = 46, x2= 92 (4.76)

Then (as I thought of it after I tossed the 10ml samples from #1 above so no comparison)
#3
used the reacted and diluted from #2 above but made the C1 sample 50% RODI/50% test water= 44, x2=88 (4.53)

so all these methods came out pretty close for a one-point curve. the 10ml sample reaction was lower overall Nitrate results as would be expected expected from the 16ml samples so the curve may not work all the way and the methodology would not necessarily support the findings anyhow (really is likely close enough and within accuracy specs for what we are doing as they all fall within 1). It was just a way to kill some time.

reference to the Salifert was reading about 5 as was the Red Sea kit (guessing from the windows of color). So we are seeing validation again.

Now - what if instead of RODI - dilute with test water as you indicated? Is the reaction complete or might it continue?

 

[ckalupa]

is another other option to test higher than 200 water = 5ml of test water and 5 ml of RODI- then do the reaction and test as normal (and 50% or 100% test water for the c1 baseline?)

gads - look at all these variables.

 

[Rick Mathew]

@Rick Mathew another thing we should coordinate: if we do the 50% dilution- should the baseline C1 sample also be 50% RODI?

I think this is ok...I dilute with the water I am testing not with RODI...Never really checked it out if it would work with RODI but since the reaction is complete it sound work


rick

 

[Rick Mathew]

@Rick Mathew another thing we should coordinate: if we do the 50% dilution- should the baseline C1 sample also be 50% RODI?

I haven't done that ...I just keep the same blank...Interesting question if it would make a difference...not sure the refractive index would be changed that much...but it might be worth a check to see...but as I said I use the same blank.

 

[Rick Mathew]

is another other option to test higher than 200 water = 5ml of test water and 5 ml of RODI- then do the reaction and test as normal (and 50% or 100% test water for the c1 baseline?)

gads - look at all these variables.

Like the "Never Ending Story"