The detection of imidazoles including histidine and some of its derivatives in biological fluids

A staining method for the detection of imidazoles including histidine and histidine-containing compounds is described. It is based on the treatment of developed high-voltage paper electrograms or paper chromatograms with bromophenol blue. The electrogram or chromatogram after drying is fixed in n-butanol, complexed with mercuric chloride, and subsequently stained with 0.2% bromophenol blue in 95% ethanol. The electrogram or chromatogram is washed while still damp with tap water until the background is clear. None of the other 20 known amino acids including tyrosine, such as are found in the synthetic mixture M150, reacted in the above staining procedure. Purines also react with the described reagent due to their imidazole configuration.