Silica gel tlc

All melting points were determined using an Electrothermal Capillary melting point apparatus and are uncorrected. Infrared (IR) spectra were recorded as thin film (for oils) in NaCl discs or as KBr pellets (for solids) with a JASCO FT/IR-6100 Spectrometer (Japan) and values are represented in cm⁻¹. ¹H NMR (500 MHz) and ¹³C NMR (125 MHz) spectra were recorded on a Jeol ECA 500 MHz spectrometer (Japan) using TMS as internal standard and chemical shift values were recorded in ppm on the δ scale. Silica gel TLC (thin layer chromatography) cards from Merck (silica gel precoated aluminium cards with fluorescent indicator at 254 nm) were used for thin layer chromatography. Visualization was performed by illumination with UV light source (254 nm). Column chromatography was carried out on silica gel 60 (0.063–0.200 mm) obtained from Merck. The mobile phase consisted of chloroform or chloroform/ethyl acetate 1/1 v/v. Tetracycline, gentamicin and ofloxacin standard antibiotic discs were purchased from Bioanalyse®, Turkey.

Pesticide standards were purchased from Chem Service (West Chester, PA, USA), and six different vegetable oils were purchased from a local grocery store. Ethanol (70%) ginseng extract devoid of pesticide residues was prepared by our laboratory. A LC-Florisil solid-phase extraction tube for pesticide purification was purchased from Supelco (St Louis, MO, USA). Silica gel TLC employed for the qualitative analysis of ginseng saponin was procured from Merck (Darmstadt, Germany). The organic solvents employed for the quantitative analysis of ginsenosides were HPLC grade (Tedia, Fairfield, OH, USA). Fourteen reference ginsenosides [Rb1, Rb2, Rc, Rd, Re, Rf, Rg1, Rg2(S), Rg2(R), Rh1, Rh2(S), Rh2(R), Rg3(S), Rg3(R)] were kindly supplied by the Korea Ginseng Corporation (Seoul, Korea).