TrAC 66, 146-157 (2015). Review of common analytical techniques and methods for the analysis of adulterants of essential oils. HPTLC methods for the analysis of numerous samples, such as Clary sage, Mint, Neroli, Niaouli and Thyme essential oils are referenced.

Stabilization and antimicrobial effect. Acta Pharm. Hungarica 57, 171-181 (1987). TLC of essential oils and carlina oxide on silica with benzene - ethyl acetate or n-hexane. Spraying with an ethanolic solution of 1% vanillin and 10% sulfuric acid and heating at 105 °C. Detection under UV 254 nm.

(Peppermint oil. Peppermint oil DAB 9, Menthae piperitae aetheroleum.) Deutsche Apotheker Zeitung 129, 2379 (1989). TLC of menthol, menthylacetate, thymol and cineol on silica with toluene - ethyl acetate 93:7. Detection with anisaldehyde - sulfuric acid regent, heating at 105°C for 3 min.

J. Chinese Herb Med. (Zhongcaoyao) 23, 518-521 (1992). TLC of ß-cyclodextrin inclusion complex of the essential oil of garlic on silica with hexane - ethyl acetate 19:1. Detection by spraying with 1% vanillin in sulfuric acid.

Amomum Villosum Lour, and its preparations.) (Chinese). J. Chinese Trad. Patent Med. (Zhongchengyao) 20 (10), 17-18 (1998). TLC on silica gel with cyclohexane - ethyl acetate 22:1. Detection by spraying with 5% vanillin in sulfuric acid and heating. Identification by finger print techniques. Quantitation by HPLC.

J. Planar. Chromatogr. 28, 173-177 (2015). HPTLC of (1) sclareol, (2) linalool, (3) linalyl acetate, and (4) carvone on silica gel with n-hexane - ethyl acetate 17:3. Detection at UV 254 nm and in daylight after dipping in vanillin - sulfuric acid followed by heating at 110 °C for 5 min. The presence of (1) in Clary Sage essential oil was demonstrated by 2D on silica gel with toluene - ethanol 17:3 in the first direction and n-hexane - acetone in the second direction, and on RP-18 phases with acetonitrile - water 7:3. Bioassays were performed by the direct bioautographic system using a Gram-negative test bacteria (Xanthomanas euvesicatoria), the luminescence gene-tagged Arabidopsis pathogen (Pseudomonas syringae pv. maculicola) and the luminescent marine bacterium (Aliivibrio fischeri) as well as a Gram-positive soil bacterium (Bacillus subtilis). For Xanthomanas euvesicatoria and Bacillus subtilis, the dried layers were dipped into cell suspension culture and after 2 h incubation in a vapor chamber at 28 °C, they were immersed into an aqueous MTT solution. The bright zones against the darker background indicate the presence of antibacterial components. For luminescent bacterial strains, the plate was dipped into bacteria suspension and evaluated with a computer-controlled cooled low-light camera. Images of bioautograms were directly recorded with an exposition time of 5 min for Aliivibrio fischeri and 15 min for Pseudomonas syringae pv. maculicola. The dark spots lacking luminescence indicate the antibacterial activity. Sclareol inhibited all tested bacteria, linalool and carvone showed antibacterial effect against all Gram-negative strains tested, while linalyl acetate only against Xanthomanas euvesicatoria and Aliivibrio fischeri.

Chinese J.Pharm.Anal. 8, 33-36 (1988) (Yaowu Fenxi Zazhi). TLC of d-menthone and 1-pulegone on alkali-modified silica with petrol ether - ethyl acetate 9:1. Detection by spraying with vanillin - sulfuric acid - ethanol 1:1:18 and heating at 80 °C for 20 min.

Olaj, Szappan, Kozmetika 38, 28-32 (1989). TLC of perfume oils on silica with benzene - ethyl acetate 8:2, dichloromethane - petrol ether 7:3 and toluene - ethyl acetate 98:2. Visualization under UV and by spraying with 3% sulfuric acid - vanillin reagent followed by heating at 105°C for 5 min.