Method and kit for detecting explosives

A method for detecting explosives selected from nitroaromatics, organic nitrates, nitramines, inorganic nitrates, chlorates and bromates, which method comprises providing a sample from a suspect source, and subjecting said sample to the steps of:

• contacting the sample with a first reagent, which is an alkaline solution of a diazotizable aminoaromatic azo-dye precursor, whereby the presence of a nitroaromatic explosive affords a distinct coloration;
• and in the absence of such coloration,
• contacting the sample, which is already in contact with said first reagent, with a second reagent containing a nitrate to nitrite ion reducing agent and a diazo-coupler which gives a colored product on reaction with a diazonium compound formed by reaction of the diazotizable aminoaromatic azo-dye precursor with nitrite ion, said second reagent being sufficiently strongly acidic in that it neutralizes and makes acidic a mixture thereof with an equal volume of said first reagent in contact with said sample, whereby the presence of an organic nitrate or nitramine explosive affords a distinct coloration;
• and in the absence of such coloration,
• contacting the sample, which is already in contact with said first and second reagents, with zinc powder suspended in a liquid, whereby the presence of inorganic nitrate affords a distinct coloration;
• and in the absence of a distinct coloration in all of the preceding steps, providing a second sample from said source, and:
• contacting said second sample with an aniline salt in a homogeneous strongly acidic solution including at least one water-miscible organic solvent, whereby the presence of chlorate or bromate affords a distinct coloration.