J. Liq. Chromatogr. Relat. Technol. 33, 957-971 (2010). HPTLC of pyritinol on silica gel with dichloromethane - methanol - formic acid 9:1:1 in a twin trough chamber. Quantitative determination by absorbance measurement at 300 nm. Repeatability and intermediate precision in matrix were 0.4 % and 3.0 %, respectively. Recoveries of spiked samples at three levels ranged from 98.5 to 101.9 % with intermediate precisions of RSD 3.7 to 4.7 %. The limit of detection and quantification was 0.6 and 2.0 µg/mL (6 and 20 ng/band), respectively. Selectivity was evaluated determining the peak purity by UV-spectrophotometry and showed correlation coefficients (r) > 0.9997. Additionally the selectivity was proven by mass spectrometry. Mass spectra showed only the analyte signals which indicated a highly satisfying selectivity.

J. Sep. Sci. 33, 2206-2210 (2010). HPTLC of fluoxetine on silica gel with toluene - glacial acetic acid 4:5. Derivatization of fluoxetine with 4-dimethylamino-azobenzene-4-sulfonyl chloride. Quantitative determination by absorbance measurement at 272 nm. The hRF of fluoxetine was 45. Linearity was between 0.05-0.35 ng/µL. Detection and quantification limits were 230 and 700 ng/µL, respectively. The intra-day and inter-day precisions showed a %RSD lower than 3.9 %. Recovery (by standard addition) was 94.7 %. The method was designed to cover the usual serum concentration level of patients taking the drug.

J. of Beihua Univ. (Natural Sci.), 11 (5), 420-423 (2010). TLC on silica gel with 1) petroleum ether (60-90 ºC) - ethyl acetate 4:1 and 2) chloroform - propanone - n-hexane - acetic acid 80:40:2:5. Detection under UV 365 nm. Derivatization by spraying with 10 % vanillin in sulfuric acid and heating at 105 ºC until the zones were visualized. Identification by comparison with the standards of the components in the individual composition drug.

J. Chromatogr. A 1218 (19), 2775-2784 (2011). A multi-enzyme inhibition assay (HPTLC-EI) based on rabbit-liver esterase (RLE) and cutinase following HPTLC allows detection of thiophosphate pesticides. Because choline esterase inhibition is more effective after conversion of thiophosphate thions into their corresponding oxons, a pre-oxidation step was added to the HPTLC-EI assay by using bromine vapor. Bromine was more effective than iodine or UV irradiation for oxidation. It increased the inhibitory strength of parathion, parathion-methyl, chlorpyrifos, chlorpyrifos-methyl, and malathion by 2 orders of magnitude. In contrast, bromine oxidation of organophosphate and carbamate insecticides resulted in a slight reduction in their inhibition factors, due to partial bromination and degradation of the parent compounds. Bromine oxidation increased the inhibition factors for demeton-S-methyl and propoxur. The HPTLC-EI system was applied to the analysis of apple juice and water samples spiked with paraoxon (0.001 mg/L), parathion (0.05 mg/L), and chlorpyrifos (0.5 mg/L) and the mean recoveries were 95-106 % and 91- 102% for RLE and cutinase, respectively.

J. Pharm. Biomed. Anal. 54, 497-502 (2011). HPTLC of three bioactive steroidal glycoalkaloid markers, solasonine (SN), solamargine (SM) and khasianine (KN) in the plant Solanum xanthocarpum. The extraction effciency of targeted SGAs from plant matrix using methanol and acidified methanol were studied using percolation, ultrasonication and microwave techniques. HPTLC on silica gel with chloroform – methanol – water. The hRf values were 31, 37, and 52 for SN, SM, and KN, respectively. Quantitative determination by absorbance measurement at 520 nm after derivatization using Dragendorffs reagent. The linearity range was 2-10 µg/band for SN and SM and 6-30 µg/band for KN. Method specificity was confirmed using hRf values, correlation of UV spectra and comparison of ionization mass spectra (ESI-MS) of marker compounds in the sample track.

J. Sep. Sci. 34, 749-760 (2011). HPTLC of (-)-epicatechin (1), (-)-epicatechin gallate (2), (-)-epigallocatechin gallate (3), caffeine (4), rutin (5), quercetin (6), gallic acid (7), ellagic acid (8), caffeic acid (9), and ferulic acid (10) in the leaves of green tea (Camellia sinensis) and guava (Psidium guajava) on silica gel with toluene – acetone – formic acid 5:4:1 for compounds (1) - (6) and toluene – ethyl acetate – formic acid – methanol 15:15:4:1 for compounds (7) - (10). Quantitative determination by absorbance measurement at 282 nm for compounds (1) - (6) and 285 nm for compounds (7) - (10). The hRf values of compounds (1) - (10) were 49, 37, 26, 60, 8, 66, 49, 34,62 and 70, respectively. Linearity was between 100-350 ng/band for compounds (1) - (5), 66.6-233.2 ng/band for compound (6) and between 50-300 ng/band for compounds (7) - (10). The limits of detection were found to be 60 ng/band for compounds (1) - (3), 30 ng for compounds (4), (5) and (8), 40 ng/band for compound (6), 20 ng/band for compound (7) and 10 ng/band for compounds (9) and (10). The limits of quantification were 100 ng/band for compounds (1) - (3), 60 ng/band for compounds (4) - (7), 30 ng/band for compounds (9) - (10), and 75 ng/band for compound (8). Inter- and intraday precisions were below 1.50 % and 2.84 %, respectively. Recoveries were found in the range of 95-100 %.

Journal of Environmental Science and Health, Part B 46, 557-568 (2011). Review on techniques and applications of TLC and HPTLC for separation, detection, qualitative and quantitative determination and preparative isolation of pesticides. Covered are sample preparation techniques, stationary phases, sample application, mobile phases, development methods using different chambers, detection under UV or by derivatization with various reagents, identification based on hRf values or by online HPTLC-MS, quantification by scanning densitometry or videodensitometry, preparative layer chromatography and thin-layer radiochromatography. Various applications are described. In the review period especially forensic analyses of human and animal samples for pesticides were numerous. The identification and quantification of components from plant extracts with pesticide activity is also reviewed and it is expected that this area will be especially active in the future given the large amount of ongoing worldwide research on phytochemical compounds.

J. Planar Chromatogr. 24, 150-153 (2011). HPTLC of tolterodine in the bulk drug on silica gel with toluene - methanol 1:1 + 1 drop aqueous ammonia in a saturated twin-trough chamber lined with filter paper; optimum saturation time was 30 min. The hRf value was 40. Quantitative determination by densitometry in absorbance mode at 284 nm. Linearity was between 200 and 1800 ng/band (r² >0.990). The limits of detection and quantification were 100 and 200 ng/band, respectively. The repeatability and intermediate precision (%RSD, n = 6), was between 0.7-0.9 % and 0.6-1.8 %, respectively. Mean recovery was 100.9 %.