J. Planar Chromatogr. 9, 189-191 (1996). TLC of 28 surface active agents (i.a. ethylene and triethylene glycols, epichlorhydrin, hexyl, octyl, decyl, and dodecyl alcohols, ethylene and triethylene glycols, and 2-methoxyethanol diglycidyl ethers) on silica with acetone - benzene 2:5. Detection with chromic acid or a mixture of cobalt(II)nitrate and potassium thiocyanate.

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.

Food Chem. 210, 613-622 (2016). HPTLC fingerprinting of triterpenoids in Siam and Sumatra benzoin balsams on silica gel with n-hexane – methanol – acetic acid 8:2:1. Detection by dipping into anisaldehyde sulfuric acid reagent for 1 s (10 mL of sulfuric acid were carefully added to an ice-cold solution of 170 mL methanol and 20 mL acetic acid, followed by the addition of 1 mL of anisaldehyde (p-methoxybenzaldehyde)), followed by heating at 105 °C for 5 min. Qualitative identification under UV 366 nm. Two specific compounds at approximately hRF 5 (violet band) and 50 (beige band) were detected in the Sumatra sample. Siam benzoin is characterized by two specific compounds at approximately hRF 5 and 10 (brown bands) and two others at approximately hRF 20 and 60 (orange bands).

J. Planar Chromatogr. 9, 39-47 (1996). HPTLC of 30 preservatives on silica, RP-18, CN, diol with 5 different mobile phases; detection with nine different methods. The procedure based on hRf values and color codes can be used for the detection and identification of the preservatives after being entered into a user-generated data base. The data compilations comprise the retention values obtained after chromatography using 5 different chromatographic systems (adsorption, partition, and reversed phase) and the colors obtained upon spraying with selected reagents, the color codes being read by the user from a color key card. By combination of more than two chromatographic systems, identification of unknown samples becomes reliable.

J. Sep. Sci. 30, 3311-3315 (2007). HPTLC of lawsone in the leaves of Lawsonia alba on silica gel with chloroform – methanol 17:3. Quantitative determination by absorbance measurement at 334 nm. The hRf value of lawsone was 40 and selectivity regarding matrix was given. Linearity was between 100 and 1000 ng/zone. The precision was 1.72 % and recovery (by standard addition) was 98.8 %.

J. Planar Chromatogr. 25, 344-348 (2012). HPTLC of two oil-soluble sunscreens, namely avobenzone (1) and octyl salicylate (2) and a water-soluble sunscreen, namely phenylbenzimidazol sulfonic acid (3) on silica gel with cyclohexane - diethyl ether 5:1 for (1) and (2) and ethyl acetate - ethanol - water 14:7:6 for (3). Quantitative determination by absorbance measurement at 300 nm for (2) and (3), and 360 nm for (1). Limits of detection and quantification were found to be 30 and 80 ng/zone for (1), and 20 and 60 ng/zone for both (2) and (3).

CBS 118, 5-7 (2017). Presentation of two HPTLC methods for 1) detection and identification of UV filter substances in suncream and 2) detection of phenolic markers in Edelweiss species (Leontopodium spp.). For 1) HPTLC of sun cream samples and standards octocrylene, avobenzone, octisalate and ensulizole on silica gel first with heptane – ethyl acetate 4:1 with chamber saturation, migration distance 70 mm, then with isopropanol, without saturation, migration distance 28 mm. Densitometric evaluation by absorbance measurement at UV 254 nm. Direct elution of target zones into a single quadrupole MS, detection in positive and negative ionization mode. For 2) HPTLC of methanolic and glycerol-based Edelweiss extracts and standards chlorogenic acid, apigenin, luteolin, luteolin-4-O-glucoside, luteoline-7-O-glucoside, leontopodic acids A and B, cynarine, and 3,5-dicaffeoylquinic acid on silica gel with butyl acetate – formic acid – water 280:100:3 with chamber saturation, migration distance 70 mm. Detection by heating the plate at 100 °C for 3 min and immersing (while still hot) into natural products reagent (1 g of 2-aminoethyl diphenylborinate in 200 mL ethyl acetate). Evaluation under UV 366 nm.

J. Planar Chromatogr. 9, 146-148 (1996). HPTLC of methyl-, ethyl-, propyl-, and butylparaben on RP-18 with acetone - water without prior chamber saturation; detection under UV 254 nm. Quantification by densitometry at 254 nm (absorbance).