Chemical detection of substances by utilizing a sample medium impregnated with solid test chemicals

A method of making an assembly, said method comprising:

• combining a sample medium with a solid test chemical,
• wherein the solid test chemical comprises zinc, and
• wherein the solid test chemical becomes dispersed uniformly on a surface of the sample medium;
• and
• associating the sample medium with at least one reagent releasable capsule after the combining step, wherein the at least one reagent releasable capsule is operable to be in fluid communication with the sample medium, wherein the at least one reagent releasable capsule comprises at least one liquid reagent, wherein the sample medium is configured to collect a substance thereon, and wherein the zinc combined with the sample medium is configured to react with an inorganic nitrate in the substance to produce nitrite ions that react with the at least one liquid reagent to produce a colored azo dye when fluid communication is established between the at least one liquid reagent in the at least one reagent releasable capsule and the sample medium.