Nitrogen oxide vapor reagent

Detection of / -aminobenzenesulfonamide derivatives is similar to that of aromatic amines, either with / -dimethylaminobenzaldehyde (p. 349), or by diazotization with vapors of nitrogen oxides and coupling (p. 349). Roux reagent is also suitable 10 g of sodium nitroprusside are dissolved in 100 ml of water, and the solution is mixed with 2 ml of 33% NaOH and 5 ml of 0.1 N KMn04, and is filtered after spraying the paper, spots of various colors appear, which are observed in visible or ultraviolet light. 

Note When combined with thin-layer chromatographic separation the reagent provides a specific detection method for nitrate and nitrite. The color development is often completed within a few minutes on silica gel plates. In the absence of ammonia vapor traces of oxides of nitrogen in the laboratory atmosphere can slowly cause the background to become reddish-brown. The simultaneous presence of the following ions in the chromatogram zones interferes with the detection of nitrate/nitrite I , 10J, IO4, MoO and H2PO2. 

In addition to iodine, other detection reagents (e.g., bromine, chlorine, formaldehyde, ammonia, diethylamine, HCl, sulfuryl chloride, sulfur dioxide, oxides of nitrogen, and ammonium bicarbonate) (see Section 11) can be applied as vapors. 

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