J. Planar Chromatogr. 23, 35-39 (2010). HPTLC of ß-carotene on silica gel (prewashed with methanol) with petroleum ether - hexane - acetone 2:3:1 in a saturated twin-trough chamber. Quantitative determination by absorbance measurement at 450 nm. Linearity was between 100 and 600 ng/band. LOD and LOQ were 0.11 and 0.37 ng/band, respectively. Average intra-day precision and inter-day-precision were 0.54 % and 0.50 %, respectively.

J. Planar Chromatogr. 23, 339-342 (2010). HPTLC of saccharin in foodstuffs (e. g. cola drinks, lemon juices, betel nut powder, mouth fresheners, ice candy, and tabletop sweeteners) on silica gel with chloroform - methanol - acetic acid 64:35:1 or acetone - isopropanol - acetic acid 60:39:1. Quantitative determination by absorbance measurement at 230 nm. Linearity was between 250 - 1250 ng/µL. The limit of detection and quantification for saccharin were 40 and 130 ng, respectively. Mean recovery from spiked samples was 102.3 % for cola drinks and 98.8 % for lemon juices. Relative standard deviation (% RSD) for cola drinks, lemon juices, ice candy, mouth freshener, betel nut powders, and tabletop sweeteners were 2.1, 4.2, 3.4, 3.0, 4.9, and 4.1 %, respectively.

J. Liq. Chromatogr. Relat. Technol. 32, 1273-1288 (2009). HPTLC of Sudan I (1), II (2), III (3), IV (4), Sudan Red B (5), Sudan Red 7B (6), Sudan Red G (7), Para Red (8), FD&C Orange 2 (9), Butter Yellow (10), Citrus Red 2 (11), Toluidine Red (12), and Disperse Orange 11 (13) in paprika, chili, and curry on RP-18 with acetonitrile - ammonia 25 % 19:1. Quantitative determination by absorbance measurement at absorption maxima of each dye. The hRf values of compounds (1) - (13) were 61, 54, 48, 29, 18, 11, 69, 63, 56, 48, 39, 18 and 11, respectively. Visual detection limits were 3 ppm for most dyes in either matrix, 5 ppm for Sudan I, 13 ppm for Disperse Orange, and 7 ppm for Butter Yellow. The limits of detection by densitometry were lower by a factor of 2 for all dyes and values of 1-3 ppm were reached except for Disperse Orange with a limit of detction of 7 ppm. Average recoveries ranged from 95.0-110.8 %. The HPTLC method is successfully applied in the routine control of illegal dyes in food by surveillance authorities.

of Chromatogr. A 1231, 59-65 (2012) Reversed-phase HPTLC of lutein, lycopene and beta-carotene standards on RP-18 (pre-washed by development with dichloromethane – methanol 1:1) with methanol – acetone 1:1 with 0.1 % of 2-tert-butylhydroquinone. The hRf value was 4 of lutein esters, 24 of beta-carotene, 32 of lycopene, and 68 of lutein. Quantitative determination of lutein by densitometry at 450 nm. The repeatabilities were %RSD = 3.4, 1.3 and 1.6 at levels of 5 ng, 15 ng and 25 ng, respectively (n = 6). The calibration curve was best fit with a polynomial function in the range of 5-30 ng. The LOD was 1.5 ng, the LOQ 5 ng. With these chromatographic conditions also dietary carotenoids lutein esters, lycopene, free lutein and ß-carotene from food supplements were identified. It was shown that the standards remain stable on the plate for 1 h after chromatogram development.

J. Planar Chromatogr. 25, 101-107 (2012). HPTLC of mixtures of the pesticides glyphosate, acephate, chlorpyrifos, malathion/methyl parathion, and isoproturon on silica gel impregnated with 0.01 % CTAB (Ncetyl-N,N,N-trimethyl ammonium bromide) and developed with hexane - acetone 1:1. LOD of the pesticides was aproximately 20 µg/band. The method can also be applied for fast determination of pesticides in cereals, vegetables and fruit grains.

Chinese J. of Jiangxi Agr. Sci. 25 (5), 117-119 (2013). Meat ducks used to be unhaired by employing certain safe depilating agents, however, a hot liquid composed of rosin and paraffin has found to be illegally applied by dipping into the hot liquid, so as to glue the liquid rosin closely onto the duck epidermis, and then by peeling the depilating agent after cooling. In this process some rosin components, such as abietic acid, may remain in the duck epidermis and even permeate the duck meat, which may be harmful to humans if daily intake exceeds 1 mg/kg body weight. Description of a procedure for testing colophony residues in the epidermis of meat ducks unhaired with rosin. TLC of the sample extracts (prepared by SPE), the standard abietic acid and depilating agent components (food grade wax and rosin glycerol ester), on silica gel with petroleum ether (60-90 °C) – ethyl acetate – glacial acetic acid 90:10:1, detection by spraying with 5 % sulfuric acid in ethanol and heating at 85 °C until the zones are visible in daylight. The LOD of abietic acid was 0.04 g/L. The method was successfully applied to the analysis of samples obtained from meat ducks unhaired with the depilating agents A) rosin - food grade wax 29:20, and B) food grade rosin glycerol ester – food grade wax 29:20, in the production conditions simulating a livestock and poultry processing enterprise.

Food Chem. 173, 749-754 (2015). Micro TLC of coloured materials in dried herbs as well as meads with juice mixed with 1 mM methanolic solution of DPPH on silica gel with hexane - acetone - ethanol 30:19:1. The method allowed to measure the total antioxidant potential.

Food Chem. 197, 285-290 (2016). HPTLC of caffeic acid (1), gallic acid (2), resveratrol (3) and rutin (4) in wine on silica gel in a two step elution with dichlormethane - methanol - formic acid 7:20:7 and with a water-in-oil microemulsion consisting of sodium dodecyl sulphate - butanol - water - heptane 8:25:8:160. Detection by spraying with 1 % 2-aminoethyl diphenylborinate solution followed by heating at 50 °C for 30 min. Quantitative determination by absorbance measurement at 366 nm. The hRF values for (1) to (4) were 67, 43, 77 and 21, respectively. Linearity was in the range of 0.06-0.02 μg/zone for (1), 0.2-1.2 μg/zone for (2), 0.5-5.0 μg/zone for (3) and 0.03-3.0 μg/zone for (4). LOD was 20 ng/zone for (1), 68 ng/zone for (2), 150 ng/zone for (3) and 9 ng/zone for (4). The intermediate precision was below 5 % (n=3). Recovery was in the range of 76-120 % for (1) to (4).