Modern J. of Integrated Trad. Chinese & Western Med. 19(31), 3439-3441 (2010). TLC on silica gel with chloroform – methanol – water 13:7:2. Detection by spraying with 10 % slfuric acid in ethanol and heating at 105 °C until the zones are visualized, evaluation under UV 366 nm. Identification of the component drugs Radix Astragali and Rhizoma Chuanxiong P.E by comparison of the retention values and color of the zones by the active compounds astragaloside and ferulic acid in the individual drug.

Acta Chromatographica 22 (2), 259-265 (2010), DOI:10.1556/AChrom.22.2010.2.8. Description of a new, simple, precise, and accurate method for quantification of (-)-epicatechin in the leaves of Cassia fistula by HPTLC on silica gel with toluene – ethyl acetate – formic acid – methanol 205:3:1:1. Quantification by densitometry at 280 nm. The linearity was in the range of 200–800 ng/band. Method precision was 1.4 %RSD and instrumental precision 1.1 %RSD. Recovery was 98.1 % and specificity regarding matrix was given.

Planta Med. 75, 711-718 (2009). For many decades, planar chromatography has been used for the analysis of plants, in particular today in its most advanced form of HPTLC. The technique is e. g. used for the identification of medicinal plants and dietary supplements, and for the detection of adulteration and quantitative determination of marker substances. Reliable qualitative and quantitative results can be achieved based on suitable instrumentation and adequate methodological concepts. The manageability of the entire planar chromatographic process has improved. Integration of biological detection systems as well as hyphenation to mass spectroscopy has widened the applicability of planar chromatography as an important analytical technique. The introduction is followed by explanation of HPTLC, use of HPTLC in plant analysis, limitations, applications (identification, detection of adulteration and quantitation), and instrumentation (chromatogram development, documentation, detection and evaluation).

J. Liq. Chromatogr. Relat. Technol. 34, 902-919 (2011). HPTLC of seven sugars (D-glucose, D-galactose, D-mannose, beta-D-fructose, alpha-D-fructose, sucrose, maltose, lactose) in food samples on silica gel with n-butanol - isopropanol - acetic acid - boric acid solution (200 mg boric acid in 10 mL water) 6:14:1:3. Detection by dipping into either aniline diphenylamine o-phosphoric acid reagent or p-aminobenzoic acid reagent. Quantitative determination by absorbance measurement at 370 nm. The HPTLC method was more sensitive by a factor of 8 for detection of sugars when compared to HPLC; only fructose showed a slightly better LOQ (difference by factor of 3). LOQ was better than 63 ng for HPTLC and about 500 ng for HPLC. Method comparison showed a good correlation and only a mean difference between both methods of 1.5 % sugar content for many food samples analyzed. HPTLC is a fully compliant method for determination of sugars in food. Application in the bioanalytical field was shown as well.

J. Planar Chromatogr. 23, 353-358 (2010). TLC of aclarubicin and doxycycline on silica gel, RP-18, cellulose, polyamide 11, and HPTLC on silica gel and RP-18 with a wide range (from 0 to 100 %) of mixtures of n-alcohols with DMSO, hexamethyldisiloxane, acetonitrile, and water in chambers saturated with mobile phase at room temperature. Detection by spraying with sulfuric acid - methanol 1:4, anisaldehyde - methanol - acetic acid - orthophosphoric acid - sulfuric acid 1:100:10:10:5 (for cellulose) and 5 % aluminium chloride in methanol (for polyamide). The effect of mobile and stationary phases on the chromatographic behavior of the compounds was studied.

J. Planar Chromatogr. 24, 236-241 (2011). HPTLC of levodopa (LEV), carbidopa CAR), and entacapone (ENT) in a combined dosage form on RP-18 (prewashed with methanol) with acetonitrile - n-butanol - water - triethylamine 1:19:2:0.002, pH adjusted to 3.6 with phosphoric acid, in a twin-trough chamber saturated with mobile phase for 25 min. Quantitative determination by densitometry in absorbance mode at 282 nm. The hRf values were 46, 64, and 87 for LEV, CAR, and ENT, respectively. Linearity was between 300-1500 ng/zone for LEV, 200-1000 ng/zone for CAR, and 200-2000 ng/zone for ENT. The intra-day and inter-day precision was below 1.8 % RSD for all drugs. The recovery for LEV, CAR, and ENT (n = 3) was between 101.0 and 102.4 %.

ex Schultes. J. Planar Chromatogr. 24, 388-393 (2011). HPTLC of p-hydroxybenzoic acid in the whole plant of Aerva lanata collected during summer, monsoon and winter on silica gel, prewashed with methanol, with ethyl actate - toluene 7:3 in a twin trough chamber. Detection under UV light at 254 nm. The hRf value of p-hydroxybenzoic acid was 73. Quantitative determination by densitometry at 252 nm. The calibration was linear in the range of 25-175 ng, with a regression coefficient of 0.9986. The %RSD for intra-day and inter-day precision was less than 2 %. The %RSD for the repeatability of sample application and measurement of area was 1.2 % and 0.9 %, respectively. The limit of detection and the limit of quantification was 0.5 and 1.4 ng, respectively. Recovery (by standard addition) was found to be 97.2 % (n = 3).

J. Planar Chromatogr. 24, 253-256 (2011). HPTLC of yohimbine on silica gel, prewashed with methanol, with toluene - ethyl acetate - diethyl amine 7:2:1 in a twin trough chamber saturated with mobile phase for 10 min at 25 +/- 2 °C. Quantitative determination by densitometry in absorbance mode at 285 nm. Linearity was between 400 and 1200 ng/band. The hRf value was 39. The repeatability as system precision and method precision (n = 6) was 0.9 and 0.8 % CV. The limit of detection and quantification was 80 ng and 260 ng. The instrument precision (n = 6), intra-day and inter-day precision (n = 3, %RSD) were 0.2, 0.1, and 0.1 %, respectively.