J. of Chromatogr. A 1218 (37), 6540-6547 (2011). New approach and application of highly automated planar chromatographic tools for powerful clean-up, called high-throughput planar solid phase extraction (HTpSPE), which is indispensable for preventing matrix effects in multi-residue analysis of pesticides in food by liquid and gas chromatography coupled to mass spectrometry, employing TLC to completely separate pesticides from matrix compounds and to focus them into a sharp zone, followed by extraction of the target zone by the TLC-MS interface, thus resulting in extracts nearly free of interference and free of matrix effects, as shown for seven chemically representative pesticides in four different matrices (apples, cucumbers, red grapes, tomatoes), and completion of clean-up of one sample in a manner of minutes. Regarding the clean-up step, quantification by LC–MS with mean recovery (against solvent standards) of 90–104% and relative standard deviations of 0.3–4.1% (n = 5) for two spiking levels of 0.1 and 0.5 mg/kg.

J. of Chromatogr. A 1218 (24), 3811-3815 (2011). HPTLC of sugars in bio-oil fractions on silica gel with acetonitrile - water 4:1, or mixtures of butanol and formic acid, followed by detection with the aniline - diphenylamine - o-phosphoric acid reagent. The method allowed for the separation of the anhydrosugars levoglucosan and cellobiosan, as well as glucose, arabinose, xylose and cellobiose without the need of pre-treatment and pre-derivatization of samples. Volatile compounds present in bio-oil did not interfere with sugar analysis, and the detrimental effect of the complex bio-oil matrix on columns and detector lifetime is avoided by using disposable HPTLC plates. It was found that the concentrations of levoglucosan and cellobiosan in bio-oil samples obtained from Pinus radiata sawdust were ranged between 1.3-2.3 % and 1.0-2.0 % respectively, while a higher levoglucosan concentration was in a bio-oil sample obtained from native wood.

J. Planar Chromatogr. 23, 373-375 (2010). HPTLC of carbosulfan on silica gel with n-hexane - acetone 4:1 in a saturated chamber. Detection by spraying with 10 % sodium hydroxide solution followed by potassium ferricyanide reagent. Semi-quantitative analysis after extraction is done against standards. Other carbamate, organophosphorus, organochlorine, and pyrethroid insecticides and constituents of viscera do not interfere. The detection limit of carbosulfan is ca. 500 ng.

J. Planar Chromatogr. 24, 373-375 (2011). HPTLC of red clover capsule extracts and formononetin, biochanin A, daidzein, glycitein, and genistein on silica gel, prewashed with methanol, with dichloromethane - glacial acetic acid - ethyl acetate 12:2:1 in a horizontal chamber saturated for 15 min. Quantitative determination by densitometry at 260 nm. The hRf value was 29, 34, 41, 48, and 59 for daidzein, glycitein, genistein, formononetin, and biochanin A, respectively. The two major isoflavones are formononetin and biochanin A. The limit of detection and quantification was 14 and 47 ng/band for formononetin and 12 and 40 ng per band for biochanin A, respectively. The recovery was 93.3-100.7 % for formononetin and 102.0-109.4 % for biochanin A.

J. Planar Chromatogr. 24, 376-380 (2011). HPTLC of stem bark extracts from D. melanoxylon and lupeol and betulin on silica gel, prewashed with methanol, with ethyl acetate - hexane 9:41 with chamber saturation for 3 min at 29 +/- 4 °C and 65 +/- 5 % relative humidity. The hRf value was 46 and 25 for lupeol and betulin, respectively. Quantitative determination by densitometry in absorption mode at 560 nm for lupeol and 510 nm for betulin. Detection by derivatization with 5 % methanol-sulfuric acid reagent. The LOD and LOQ was 40 and 100 ng/zone for lupeol and 50 and 100 ng/zone for betulin, respectively. The instrument precision and repeatability (n = 6) were 0.8 and 1.3 % for lupeol and 1.1 and 1.2 % for betulin, respectively. The linearity range was 100-500 ng/zone for both lupeol and betulin. The intra-day and inter-day precision was 1.1-1.7 % and 1.3-2.0 % for lupeol and 0.8-1.9 % and 1.9-2.2 % for betulin.

Brazilian Journal of Pharmacognosy 21, 818-823 (2011). This review describes recent advances in HPTLC automatization as a useful tool for the analysis of complex mixtures of natural products. The author also compares HPTLC with TLC and HPLC. The review provides a general perspective for HPTLC fingerprint approach for the analytical determination of botanicals.

J. Planar Chromatogr. 24, 222-226 (2011). HPTLC of lamotrigine in human serum with chloramphenicol as internal standard on silica gel, prewashed with methanol, with ethyl acetate - methanol - 32 % aqueous ammonia 17:2:1 in a saturated twin-trough chamber. Quantitative determination by densitometry at 280 nm. The hRf of lamotrigine was 37. Linearity was between 0.6 and 300 ng/band, corresponding to 0.06-30.00 ng/µL lamotrigine in human serum after extraction and application of 1 µL to the chromatographic plate. The correlation coefficient was 0.998. Intra-assay and inter-assay precision (%RSD) were in the range of 0.5-2.9 % (n = 3) and 1.6 -2.9 % (n = 9), respectively. LOD and LOQ were 16 and 42 pg/zone, respectively. Recovery (by standard addition) was between 94.1-101.3 %, with %RSD not higher than 3.5 %.

J. Planar Chromatogr. 24, 48-52 (2011). HPTLC of hydroquinone on silica gel with chloroform - methanol 17:3 in a twin-trough chamber after saturation for 30 min at 25 °C. Quantitative determination by densitometry in absorbance mode at 289 nm. The hRf of hydroquinone was 51. Linearity was between 100 and 2500 ng/zone. Mean recovery was 99.2 %, with %RSD between 1.7-2.0 %. The intra-day precision (n = 3) as %RSD was 0.9-1.1 % and the inter-day precision 1.0-1.2 %. The LOD and LOQ was 39 and 116 ng/band, respectively.