J. Sep. Sci. 31, 3537-3542 (2008). After solid phase extraction of water samples HPTLC of clofentezine (1), neburon (2), chlorfenvinphos (3), lenacyl (4), trifluralin (5), thiram (6), procymidone (7), flufenoxuron (8), tralkoxydim (9), propaquizafop (10), and dinoseb (11) on silica gel with ethyl acetate – n-heptane 2:8, 3:7, 4:6, or 7:3 as mobile phase. Quantitative determination by absorbance measurement between 200 and 600 nm. Selectivity regarding matrix was given. Linearity was 0.1-1.5 µg/spot for (1), 0.2-1.0 µg/spot for (2), 0.5-1.0 µg/spot for (3), 0.2-1.0 µg/spot for (4), 0.3-9.0 µg/spot for (5), 0.2-1.0 µg/spot for (6), 2.0-11.0 µg/spot for (7), 0.1-2.0 µg/spot for (8), 0.3-1.0 µg/spot for (9), 0.1-1.0 µg/spot for (10), and 0.2-1.0 µg/spot for (11). The limits of detection and quantification were 0.23 and 0.70 µg/spot for (1), 0.06 and 0.18 µg/spot for (2), 0.16 and 0.49 µg/spot for (3), 0.04 and 0.12 µg/spot for (4), 0.06 and 0.18 µg/spot for (5), 0.16 and 0.49 µg/spot for (6), 0.65 and 1.92 µg/spot for (7), 0.10 and 0.31 µg/spot for (8), 0.07 and 0.22 µg/spot for (9), 0.06 and 0.17 µg/spot for (10), and 0.08 and 0.24 µg/spot for (11). The optimal wavelenght for quantification was 278 nm for (1), 249 nm for (2), 247 nm for (3), 273 nm for (4), 277 nm for (5), 281 nm for (6), 208 nm for (7), 268 nm for (8), 284 nm for (9), 245 nm for (10), and 366 nm for (11). Advantages of the technique over the HPLC method are highlighted.

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 %.

J. Planar Chromatogr. 25, 262-268 (2012). HPTLC of paraquat (1), diquat (2), difenzoquat (3), mepiquat (4), and chloromequat (5) in water on silica gel with 1-propanol - methanol - 2.5 N NaCl 1:1:3. Quantitative determination by absorbance measurement between 500 and 535 nm. The hRf values of compounds (1) to (5) were 21, 30 36, 52 and 56, respectively. Limits of quantification were 5 ng/zone for (1), 2 ng/zone for (2), 25 ng/zone for (3), 15 ng/zone for (4) and 9 ng/zone for (5). Recovery rates for compounds (1) to (5) were 50.7, 65.2, 59.6, 45.1 and 33.7 %, respectively.

CBS 112, 5-7 (2014). HPTLC-AMD of sediment samples and standards 17α-ethinylestradiole, 17ß-estradiole, estrone and bisphenol A on silica gel with a two step gradient, first step with methanol to 20 mm, second step with ethyl acetate - n-hexane 1:1 to 80 mm. Detection with the p-YES-bioassay by dipping in yeast cell suspension (the cell number of the genetically modified yeast strain (Saccharomyces cerevisiae BJ3505) was determined by photometry and diluted to 150 ± 50 Formazin Attenuation Units) followed by incubation for 3 h at 30 °C in a saturated steam atmosphere. Then the enzyme substrate solution (0.5 mg/mL 4-methylumbelliferyl-ß-D-galactopyranoside solution) was sprayed on the TLC plate followed by a second incubation for 30 min at 37 °C. Detection under UV 254 nm and quantitative fluorescence measurement at UV 320/>400 nm. Two blue fluorescent zones with estrogenic activity were detected at hRF 65 and 80.

J. Planar Chromatogr. 29, 227-228 (2016). HPTLC of carbaryl in visceral sample on silica gel with hexane – ethyl acetate 9:1. Detection by spraying with 10 % NaOH solution followed by a mixture of a 10 % aqueous sodium bromide solution and a 10 % aqueous copper chloride solution (mixture ratio most likely 1:1, however, not reported). The hRF value for carbaryl was 51.

J. Chromatogr. A 1519, 121-130 (2017). Development of an approach to create inhibition chromatograms from the images, which are employed to detect the effect in effect-directed analysis (EDA) with HPTLC, by using the example of the HPTLC-bioluminescence inhibition test. Determination of 50 % effect concentration (EC50) value from the dose-response relationship to describe the strength of the effect, where the known application volumes, instead of the concentration, are used, because the inhibiting compounds are generally unknown and thus their concentrations are also unknown. This enables the calculation of the application volume necessary to achieve 50 % inhibition. Introduction of a new value for comparing effects referred to as reciprocal iso-inhibition volume (R/V), which is used to compare inhibition bands within and between plates. Description of the entire evaluation by the means of two samples from a contaminated site using the HPTLC-bioluminescence inhibition assay.

AnaI. Letters 20, 235-257 (1987). One- and two-dimensional TLC of azo dyes of phenolic compounds in water and grain on silica with chloroform acetone 9:1 or benzene - di-n-propylamine 4:1 for 1-D TLC, and with the two solvent mixtures for 2-D TLC. Assessment by comparison of the spots with standards. Detection limit 0.005-0.2 mg.

J. of Medicinal Chemistry 32, 1522-1528 (1989). TLC of aprophen analogues on silica with chloroform - methanol 95:5. Visualization under UV and by exposing to iodine vapor.