Hanna Nitrate chemistry/filter products

[rayadog]

Would somebody be able to help me understand what reactions are allegedly taking place in within the Hanna UL Nitrate test method? I’m trying to find some “cheap” filter discs to replace the apparatus and filter paper. I would like to make sure to look for the correct type of filter disc.

I’m asking because I don’t know; I’m not even the most average chemist. From what I can tell, the method starts with “reagant A” which is Ammonium hydroxide. So added to seawater should result in ammonium ions and metal hydroxides etc.? The next step is to add “reagent B” which is EDTA and zinc. I’m not sure what the zinc does.. (set up for a reactive color after adding part C [reagent C js Potassium disulfate] or just color the EDTA for user “friendliness”?). < total guess/made up. But then is the EDTA going to bind with my hydroxides, chelating them and that’s what I filter out? How did I do?

So… if I’m not wrong, which would be surprising… is literally any filter (given the size) appropriate as long is it’s grabbing the EDTA and not the water and ammonium (or is it nitrate ions?)? I mean pvdf, ptfe, nylon, ca, pes? I was led to believe the included filter paper was cellulose. If that’s true would the cellulose acetate be fine as a general water filter?

I’m absolutely fine being wrong which is why I’m asking. Please educate me.

 

[Randy Holmes-Farley Verified Community Expert]

I cannot confidently answer the question about what is needed in terms of the chemistry of the paper, if anything.

One straightforward way to get an answer is try one and compare the result to the Hanna paper,

 

[rayadog]

Thanks, I thought I might do that.

 

[Dan_P]

Would somebody be able to help me understand what reactions are allegedly taking place in within the Hanna UL Nitrate test method? I’m trying to find some “cheap” filter discs to replace the apparatus and filter paper. I would like to make sure to look for the correct type of filter disc.

I’m asking because I don’t know; I’m not even the most average chemist. From what I can tell, the method starts with “reagant A” which is Ammonium hydroxide. So added to seawater should result in ammonium ions and metal hydroxides etc.? The next step is to add “reagent B” which is EDTA and zinc. I’m not sure what the zinc does.. (set up for a reactive color after adding part C [reagent C js Potassium disulfate] or just color the EDTA for user “friendliness”?). < total guess/made up. But then is the EDTA going to bind with my hydroxides, chelating them and that’s what I filter out? How did I do?

So… if I’m not wrong, which would be surprising… is literally any filter (given the size) appropriate as long is it’s grabbing the EDTA and not the water and ammonium (or is it nitrate ions?)? I mean pvdf, ptfe, nylon, ca, pes? I was led to believe the included filter paper was cellulose. If that’s true would the cellulose acetate be fine as a general water filter?

I’m absolutely fine being wrong which is why I’m asking. Please educate me.

I think the important parameter is pH when you search for an alternative filter. Don’t use a filter media that is sensitive to high pH. Also, you don’t want pore size to be too small because the filter will clog before you finish filtering. Likewise, don’t use too large of a pore size. Look up the pore size for Whatman 1 filter paper. Try using this value as the largest pore size. I am not sure about the lower limit. Just guessing, 1 micron might be the lower limit.

 

[rayadog]

I think the important parameter is pH when you search for an alternative filter. Don’t use a filter media that is sensitive to high pH. Also, you don’t want pore size to be too small because the filter will clog before you finish filtering. Likewise, don’t use too large of a pore size. Look up the pore size for Whatman 1 filter paper. Try using this value as the largest pore size. I am not sure about the lower limit. Just guessing, 1 micron might be the lower limit.

Thanks, I think it might be 4-5 microns but I’ll try what I can get my hands on. I’ll definitely consider pH, likely cellulose or pes on availability.