J. Chromatogr. A 1217 (43), 6600-6609 (2010). A review on hyphenations of planar chromatography and its most important subcategory HPTLC. Examples from the field of natural product search, food, and lipid analysis point out the hyphenation with effect-directed analysis and mass spectrometry and illustrate the efficiency gain. Depending on the task at hand, hyphenations can readily be selected, for example with MS, bioassays etc. as required to reach the relevant information about the sample. At the same time, information is obtained for many samples in parallel. The flexibility and the unrivalled features through the planar format valuably assist separation scientists.

J. Chromatogr. B 878 (17-18), 1337-1345 (2010). Use of rabbit liver esterase, Bacillus subtilis esterase, and cutinase from Fusarium solani pisi for the detection of 21 organophosphorus and carbamate pesticides by HPTLC-enzyme inhibition assays (HPTLC-EI) on silica gel with n-hexane - ethyl acetate - dichloromethane 13:4:3. HPTLC-EI assay of three groups of organophosphate and carbamate insecticides with 1) n-hexane - ethyl acetate 63:37, 2) chloroform - ethyl acetate 9:1, 3) n-hexane - acetone - dichloromethane 15:2:3. Detection by treatment with Fast Blue Salt B and enzymatically coupling to alpha-naphthol released from the respective acetate used as substrate. Quantification by densitometry at 533 nm. Calculation of enzyme inhibition factors derived from HPTLC-EI using linear calibration curves. Comparison to published inhibition constants showed good correlation. The limits of detection ranged from a few pg/zone for organophosphates as strongest inhibitors to a few ng/zone for most carbamates and was around 60 ng/zone for chlorpyrifos and 14 ng/zone for parathion without oxidation. The CUT was able to detect insecticides of high and low inhibitory power in the range of ng to µg/zone. The HPTLC-EI with rabbit liver esterase was applied to the analysis of apple juice and drinking water samples spiked with paraoxon (0.001 mg/L), parathion (0.05 mg/L) and chlorpyrifos (0.5 mg/L). The mean recovery was 71-112 % with standard deviations of 2.0-18.3 %.

Talanta, 80 (5), 2007-2015 (2010). Presentation of a method for determination of oxybutynin hydrochloride (OX) in presence of its degradation product and additives in its pharmaceutical formulations. UV spectrophotometry using the first derivative of ratio spectra and measurment at 216 nm. Chemometric analysis using principal component regression and partial least-squares. HPTLC of OX and its degradation products methylparaben and propylparaben on silica gel with chloroform - methanol - ammonia - triethylamine 500:15:2.5:1. Quantitative determination by densitometry at 220 nm. Comparison of the results obtained with all three methods showed no significant differences.

Anal. Chim. Acta 690 (2), 148-161 (2011). Chromatographic fingerprinting has been generally accepted as analytical method for the quality control of herbal medicines. This review describes the evolution of the regulations and guidelines on the quality control of herbal medicines, and reviews the established analytical techniques in TLC, HPLC, UHPLC, hydrophilic interaction chromatography, and GC. Emphasis is put on the most recent developments, such as miniaturized techniques, new stationary phases, analysis at high temperatures and multi-dimensional chromatography. The new chemometric data handling techniques are discussed.

CBS 106, 5-6 (2011). HPTLC on 1) ProteoChrom silica gel with 2-butanol – pyridine – ammonia 25 % – water 39:34:10:26; on 2) ProteoChrom cellulose with 2-butanol – pyridine – acetic acid – water 15:10:3:12 by two-dimensional development and on 3) silica gel with the developing solvent from 2). Detection by spraying with ninhydrin, fluorescamine, or triethylamine reagent. Evaluation under daylight and UV 366 nm. Detection by mass spectrometry by scanning the plate with a self modified desorption electrospray beam. In one-dimensional HPTLC up to 20 bands can be separated. By two-dimensional separation this number can be increased. Particularly suited are cellulose HPTLC plates.

J. of Chromatogr. Sci. 49, 129-135 (2011). TLC on silica gel with ethyl acetate – chloroform – formic acid – triethyl amine 70:30:1:1. Detection and quantification by densitometry. Good correlation between the integrated peak area of the studied drugs and their corresponding concentrations was found in different ranges.

J. of Guangzhou Chem. Engin. 39(1), 144-145 (2011). A course on the technology of TLC/bioautography applied for the analysis of TCM was set-up to enhance students’ understanding of theoretical knowledge and to train and improve the interest and skill of students in chemical experiments. Demonstration of the TLC analysis of rutin and quercetin in Flos Sophorae on silica gel with ethyl acetate – formic acid – water 8:1:1. Detection under UV 254 nm and 366 nm, and by immersing into a solution of 1,1-diphenyl-2-picrylhydrazyl in ethanol (DPPH radical reagent). The result of this practice was satisfactory, and the course proved to be a good example to utilize the modern technology in the experimental teaching.

CBS 107, 9-10 (2011). Extraction of pesticides from fruit and vegetable samples by QuEChERs method. TLC of acetamiprid, azoxystrobin, chlorpyriofos, fenarimol, mepanipyrim, penconazole and pirimicarb on amino phase aluminum foil (prewashed with acetonitrile) with acetonitrile over a migration distance of 75 mm in the first direction. After drying development in the backwards direction over 45 mm with acetone. Evaluation under UV 254 nm, UV 366 nm, white light and under UV 366 nm after immersion in primuline solution. Extraction of the target zone by TLC-MS interface with acetonitrile - 10 mM ammonium formate 1:1. Average recoveries of the seven pesticides were 90-104 % with %RSD of 0.3-4.1 % (n = 5). This new high-throughput planar solid phase extraction method for multi-residue analysis of pesticides in food allows a rapid and efficient clean-up at low costs and low solvent consumption.