A thin layer chromatographic method has been developed that distinguishes and differentiates true cardamom (Elletaria cardamomum Maton) and greater cardamom (Amomum subulatum Roxb). Extracted volatile oils are chromatographed on silica gel G with n-hexanediethyl ether (80+20) solvent system and visualized with a saturated solution of antimony trichloride in chloroform. The chromatographic pattern permits the detection of adulteration of one by the other at levels as low as 5%.

A rapid thin layer chromatographic method has been developed to detect Carum bulbocastanum Koch in Carum carvi Linn. The volatile essential oils are developed on silica gel G plates, using benzene-petroleum ether and visualized by 2,4-dinitrophenylhydrazine spray. This procedure can also differentiate mixtures of the 2 seeds.

A rapid thin layer chromatographic test has been developed to differentiate caraway, coriander, and cumin. Samples are steam-distilled and 1% solutions of the volatile oils are chromatographed on silica gel G plates, using benzene- chloroform ( l+l ) as the solvent system. After exposure to iodine vapor, characteristic spots develop which can be used to distinguish and differentiate caraway, coriander, and cumin.

Thin layer chromatography has been investigated for the identification of cashew nut shell, one of the common adulterants in ground coffee, tea, and chicory. The ether extract of the sample is applied to silica gel C plates and developed with benzene-dioxane-acetic acid (90+25+4) . Cashew nut shell shows 3 distinctive spots (Rf 0.7, 0.54, and 0.34) with diazotized benzidine which are totally absent in tea, coffee, and chicory. The spots have been identified as anacardic acid, cardol, and anacardol, respectively.

The volatile oils of randhuni and ajowan seeds are extracted and spotted on silica gel G thin layer plates. The plates are developed in either benzene-petroleum ether (1+1) or chloroform-pyridine-benzene (65+5+30). Spraying with anisaldehyde-sulfuric acid reagent shows a single red spot for ajowan and 4 spots (violet, greenish yellow, violet, and blue) for randhuni. This procedure can also differentiate admixtures of the 2 and seeds of other Umbelliferae.