[sejuwalsachin]

I am working with nitrate test strip using paper device. I am having a problem with stability of Griess reagent which is needed for the color change in presence of nitrate in the sample. For this, I used Whatman No.1 paper strip to coat Griess reagent along with zinc dust but I could not get satisfactory result.Could anyone has idea how to make nitate paper strip, especially to determine nitrate level in soil ?
Thank you.