Nitrate test

[Gogo007]

I really want to make my DIY nitrate test was looking for a lot of methods all depends in N.E.D ethyelenediamine dihydrochloride

If anyone please know good method for high range nitrate this gonna be helpful

 

[Gogo007]

?!

 

[JimWelsh]

So, nitrate methods generally rely upon reduction of nitrate to nitrite, which is then quantified using Griess reagents (sulfanilamide + NEDD). There are various methods for reducing nitrate to nitrite. Which one do you intend to use? The resulting azo dye has a very high molar extinction coefficient. This can result in an unreasonably high absorbance of the final assay depending upon the concentration of nitrate, the degree to which the reduction to nitrite is complete, and the sample-to-reagent ratio. Any existing nitrite in the sample can obviously interfere. What detection method do you intend to use? Your question is not an easy one to answer with so little information.

EDIT: This is a good start: https://tarjomefa.com/wp-content/uploads/2018/06/TarjomeFa-F708-English.pdf

 

[Gogo007]

So, nitrate methods generally rely upon reduction of nitrate to nitrite, which is then quantified using Griess reagents (sulfanilamide + NEDD). There are various methods for reducing nitrate to nitrite. Which one do you intend to use? The resulting azo dye has a very high molar extinction coefficient. This can result in an unreasonably high absorbance of the final assay depending upon the concentration of nitrate, the degree to which the reduction to nitrite is complete, and the sample-to-reagent ratio. Any existing nitrite in the sample can obviously interfere. What detection method do you intend to use? Your question is not an easy one to answer with so little information.

EDIT: This is a good start: https://tarjomefa.com/wp-content/uploads/2018/06/TarjomeFa-F708-English.pdf

Thank you very much for this information .. acually i am trying to make diy test for nitrate i am going to use spectrophotometer .. its better to be in high range like the high range test kits .. and i want if its possible to use not more than two reagents because i may automate this process .. thats all

 

[taricha]

If you are trying to DIY automatable versions of chem tests, you should definitely leave NO3 for last. It's like the hardest one.

 

[Gogo007]

If you are trying to DIY automatable versions of chem tests, you should definitely leave NO3 for last. It's like the hardest one.

Actually i have made alkalinity and i have made phosphate i will post pictures .. alkalinity was the easy one its based in acid base titration .. phosphate also was not that hard based on colormitry used ammonium molybdate and stannous chloride .. measure absorbance@680nm and it great .. now the time for nitrate and yes its so hard thats why i am asking about easy method with two reagents max to be easy and i do not need much accuracy for nitrate in range of 1 to 20 ppm and i do not care about the low ones less than 1ppm .. i will show you some picture of the system i have made its dosing system with analyser not linked the phosphate yet to the app ..

 

[Gogo007]

So, nitrate methods generally rely upon reduction of nitrate to nitrite, which is then quantified using Griess reagents (sulfanilamide + NEDD). There are various methods for reducing nitrate to nitrite. Which one do you intend to use? The resulting azo dye has a very high molar extinction coefficient. This can result in an unreasonably high absorbance of the final assay depending upon the concentration of nitrate, the degree to which the reduction to nitrite is complete, and the sample-to-reagent ratio. Any existing nitrite in the sample can obviously interfere. What detection method do you intend to use? Your question is not an easy one to answer with so little information.

EDIT: This is a good start: https://tarjomefa.com/wp-content/uploads/2018/06/TarjomeFa-F708-English.pdf

https://www.epa.gov/sites/default/files/2015-08/documents/method_352-1_1971.pdf

i found this method but not sure about it

 

[JimWelsh]

https://www.epa.gov/sites/default/files/2015-08/documents/method_352-1_1971.pdf

i found this method but not sure about it

I'm laughing out loud at the concentration of the H2SO4 and the temperature required. <sarcasm> Yeah I want to be dealing with a 5:1 concentrated H2SO4 solution heated to 100C! </sarcasm>:

"This method is based upon the reaction of the nitrate ion with brucine sulfate
in a 13 N H2SO 4 solution at a temperature of 100°C. The color of the resulting
complex is measured at 410 nm. Temperature control of the color reaction is
extremely critical."

 

[biom]

Be aware not all nitrate test methods are suitable for saltwater or at least should be adapted for saltwater testing

 

[biom]

I'm laughing out loud at the concentration of the H2SO4 and the temperature required. <sarcasm> Yeah I want to be dealing with a 5:1 concentrated H2SO4 solution heated to 100C! </sarcasm>:

"This method is based upon the reaction of the nitrate ion with brucine sulfate
in a 13 N H2SO 4 solution at a temperature of 100°C. The color of the resulting
complex is measured at 410 nm. Temperature control of the color reaction is
extremely critical."

The standard is from 1971... but similar methods are still used. The method used in our lab self generates extreme heat when mixes with the sample and you need to cool it to room temperature before measurement took place. Not the safest method but quite accurate, not suitable for saltwater.

 

[Gogo007]

I'm laughing out loud at the concentration of the H2SO4 and the temperature required. <sarcasm> Yeah I want to be dealing with a 5:1 concentrated H2SO4 solution heated to 100C! </sarcasm>:

"This method is based upon the reaction of the nitrate ion with brucine sulfate
in a 13 N H2SO 4 solution at a temperature of 100°C. The color of the resulting
complex is measured at 410 nm. Temperature control of the color reaction is
extremely critical."

So if it must be controlled at 100c this is going to be hard.. i know there are test method based on zinc dust .. please if you have details for this zn dust method test procedure and if it will work for seawater .. your help is appreciated

 

[Gogo007]

Be aware not all nitrate test methods are suitable for saltwater or at least should be adapted for saltwater testing

Do not you have a hint for any of those methods please ?

 

[biom]

Do not you have a hint for any of those methods please ?

Not sure I can help. Easiest way is to use one of the available nitrate tests (salifert or any other) and adapt it for spectrophotometry. But if you are going to commercialize the product then I am afraid you'll need to invest more in the process and hire a chemist.

 

[taricha]

Nitrate is almost always done in a saltwater context with using solid metal (zinc, or the more toxic cadmium) to reduce to NO2, then it's the basic 1-step NO2 test.
The only way I know of that could be liquid only at near room temp for saltwater is chromotropic acid. It's not very sensitive, you could use a colorimeter and distinguish like 0 vs 2ppm but probably not much better than that.
And I think the concentrations of Sulfuric acid and maybe also chromotropic acid involved are high. I've only done the chromotropic acid test with pre-made hanna vials.

Hach gives a decent overview of the situation (attached).

I've never looked closely enough at API to confirm that there are tiny zinc solids suspended in the thick solution that requires you to shake it insanely before adding the drops.

If I were building my own automated system that could only manipulate liquids, I might consider the possibility of making a fixed in-place packed column of zinc - then dripping the sample water through it into the reaction container, then do the color forming reaction with the NO2 that is formed. That way no solids would need to be manipulated or added into the reaction container itself.

If you do find a low temp, sensitive, not-too-toxc, liquid only saltwater Nitrate test - be sure to publish the results. It would be of significant scientific interest!

like I said

If you are trying to DIY automatable versions of chem tests, you should definitely leave NO3 for last. It's like the hardest one.

 

[taricha]

oops. apparently I don't actually know how API nitrate test works. The reagent 2 that you have to shake insanely does not appear to contain any metal solids, but instead is two separable liquids as you can see here.

 

[Gogo007]

Nitrate is almost always done in a saltwater context with using solid metal (zinc, or the more toxic cadmium) to reduce to NO2, then it's the basic 1-step NO2 test.
The only way I know of that could be liquid only at near room temp for saltwater is chromotropic acid. It's not very sensitive, you could use a colorimeter and distinguish like 0 vs 2ppm but probably not much better than that.
And I think the concentrations of Sulfuric acid and maybe also chromotropic acid involved are high. I've only done the chromotropic acid test with pre-made hanna vials.

Hach gives a decent overview of the situation (attached).

I've never looked closely enough at API to confirm that there are tiny zinc solids suspended in the thick solution that requires you to shake it insanely before adding the drops.

If I were building my own automated system that could only manipulate liquids, I might consider the possibility of making a fixed in-place packed column of zinc - then dripping the sample water through it into the reaction container, then do the color forming reaction with the NO2 that is formed. That way no solids would need to be manipulated or added into the reaction container itself.

If you do find a low temp, sensitive, not-too-toxc, liquid only saltwater Nitrate test - be sure to publish the results. It would be of significant scientific interest!

like I said

I have found way using zinc dust with help of
Sulfanilic acid solution and
α-Naphthylamine solution

I will try it and i think zn dust can be prepared as solution

Thank you so much for your detailed help i really appreciate that and i will keep posting what i have done this is not commercial and will be open source for all to use it as final solution for online reef analyzer

 

[Gogo007]

Sulfanilic acid solution and
α-Naphthylamine solution
Can do it i think alone i am not sure but i will get those and i will try myself also beacuse zn work as reducing agent and i think sulfanilic acid could reduce nitrate at concentration of 5N

 

[Gogo007]

By the way i am graduated from faculty of science physics and chemistry department but my current job was so far from analytical chemistry thats why i really asking for help

Not sure I can help. Easiest way is to use one of the available nitrate tests (salifert or any other) and adapt it for spectrophotometry. But if you are going to commercialize the product then I am afraid you'll need to invest more in the process and hire a chemist.

 

[taricha]

Revisiting this....

I've never looked closely enough at API to confirm that there are tiny zinc solids suspended in the thick solution that requires you to shake it insanely before adding the drops.

oops. apparently I don't actually know how API nitrate test works. The reagent 2 that you have to shake insanely does not appear to contain any metal solids, but instead is two separable liquids as you can see here.

Never mind: I found the zinc metal in the API test....

It took it a long time to settle out and it's very tiny - but there's the metal (Zn) solids in the reagent 2 you have to vigorously shake.