Google Scholar shows plenty of papers on J resolved NMR spectroscopy.

Can you add what have you searched so far from books and reliable webpages (not from random webpages)?

The paper you linked should not have seen light of the day (meaning don't waste your time on this paper). Find better colorimetric methods in the literature and your supervisor should guide you.

Buttonwood, I think the OP is confused by the equation 13, the powers of E are confusing because it looks like a series expansion. A series expansion cannot have units.

You will not find this information anywhere, at least in public databases.

Unnecessary down voting serves no purpose to the community. Have courtesy and appreciate the time of others and point out the issue if any. Being lazy and pressing buttons won't work.

Always define the abbreviations in scientific writing. OER, RHE, OCP, LSV, etc.

@new, They are colloids.

Mathew, this is not a quantitative method for nitrate determination in water or soil samples. The OP's idea of using thiosulfate is not conceptually right. Thiosulfate will not react with nitrate ion. I have a reference but the OP needs to show some effort with hints in the comments.

Poutnik, this is rather old method. Most methods use colorimetric reagents and a spectrophotometer.