Herbicides which contain primary or secondary amino groups may be detected on thin layers of silica gel G or silica gel H with 1% tert-butyl hypochlorite, followed with an aqueous solution of 1% HE and 1% soluble starch. Detection limits range from approximately 1 [mu]g to less than 0.05 [mu]g, depending upon the herbicide in question. The technique also appears to be effective for aromatic or aliphatic iodides.