Asian Journal of Chemistry 23(10), 4351-4354 (2011). HPTLC of nateglinide in tablet dosage form on silica gel with n-hexane - methanol - isopropanol 75:15:10. The hRf value was 56. Quantitative evaluation by absorbance measurement at 210 nm. The method was linear in the range of 300-1000 ng/band. The average recovery was 98.5 %.

J. Planar Chromatogr. 24, 248-252 (2011). TLC of MGDG and DGDG on silica gel with chloroform - methanol -10 % acetic acid 40:10:1. Detection by spraying with a 25 % solution of sulfuric acid in methanol, followed by heating at 105 °C for 5 min. Quantitative determination by densitometry at 477 nm. The hRf values were 48 for DGDG and 80 for MGDG. The limit of detection and quantification was 200 and 500 ng/band for DGDG and 500 and 1500 ng/band for MGDG. The linear range was 0.5-5.5 µg/band for DGDG and 1.5-5.5 µg/band for MGDG, respectively. The recovery (n= 9) was 95.7 % for DGDG and 93.5 % for MGDG. The repeatability and intermediate precision of results, as %RSD, was between 1.7-2.7 % for DGDG and 1.7-2.6 % for MGDG.

ex Schultes. J. Planar Chromatogr. 24, 388-393 (2011). HPTLC of p-hydroxybenzoic acid in the whole plant of Aerva lanata collected during summer, monsoon and winter on silica gel, prewashed with methanol, with ethyl actate - toluene 7:3 in a twin trough chamber. Detection under UV light at 254 nm. The hRf value of p-hydroxybenzoic acid was 73. Quantitative determination by densitometry at 252 nm. The calibration was linear in the range of 25-175 ng, with a regression coefficient of 0.9986. The %RSD for intra-day and inter-day precision was less than 2 %. The %RSD for the repeatability of sample application and measurement of area was 1.2 % and 0.9 %, respectively. The limit of detection and the limit of quantification was 0.5 and 1.4 ng, respectively. Recovery (by standard addition) was found to be 97.2 % (n = 3).

J. Planar Chromatogr. 24, 497-502 (2011). HPTLC of isoswertisin-5-O-beta-D-glucoside (1), swertiamarin (2), and swertisin (3) as biomarkers on silica gel with ethyl acetate - methanol - water 16:2:1 in a twin-trough chamber with saturation for 30 min. Quantitative determination by absorbance measurement at 287 nm. Linearity was between 25-75 µg/mL for (1), 200-600 µg/mL for (2), and 100-300 µg/mL for (3). The relative standard deviation for instrumental precision, intra-assay precision, and intermediate precision was below 2 %. The average recovery was 99.9 % for (1), 99.6 % for (2), and 99.1 % for (3). The hRf values were 32 for (1), 41 for (2), and 52 for (3). The limit of detection was 570 ng, 740 ng, and 300 ng for (1), (2), and (3), respectively.

J. of Chromatogr. A 1218 (33), 5693-5704 (2011) A micro-TLC platform for the fast analysis of low-molecular mass compounds from spirulina samples was developed. The target compounds were extracted with methanol, acetone or tetrahydrofuran. HPTLC on RP-18W with acetone - n-hexane 3:7 in an unsaturated chamber using a temperature controlled micro-planar chromatographic device based on a horizontal chamber. Detection under visible light before and after exposure to iodine vapor. Pictures of the chromatograms were acquired with an office scanner and digitalized. The quantitative data was analyzed using cluster analysis and principal components analysis. With this method it was possible to distinguish genuine spirulina and non-spirulina samples as well as fresh and expired commercial products.

Chinese J. of Pharm. Anal. 29 (9), 1458-1461 (2009). TLC of Ershiwuwei Luronghao pill extracts on silica gel with toluene - ethyl acetate - water - formic acid 20:10:1:1. Detection under UV 365 nm. Identification of aristolochic acid A by comparison of the hRf value with the standard. The method was rapid and precise and suitable for the quality control of the medicine.

J. Planar Chromatogr. 23, 365-368 (2010). HPTLC of palmitoyl hexapeptide (an antiwrinkle peptide) on silica gel with toluene - ethanol 9:1 in a twin-trough chamber with saturation for 30 min at room temperature (25 +/- 2 °C). The hRf was 33. Quantitative determination by absorbance measurement at 211 nm. Linearity was between 10 and 30 ng/band. The LOD and LOQ was 3 and 9 ng/band, respectively. The intra-day precision (%RSD, n = 6) was 0.9-1.5 % and the inter-day precision 0.9-1.4 %. The small %RSD obtained after small changes of the method conditions indicate the method is robust. The recovery of the method was in the range of 98.9-101.3 %.

J. Planar Chromatogr. 24, 281-289 (2011). TLC of tartrazine (E 102), quinoline yellow (E 104), azorubin (E 122), ponceau 4R (E 124), allura red AC (E129), patent blue V (E 131), and brilliant blue FCF (E133) on RP-18 or cyano phase with methanol - acetate or citric buffer containing diethylamine or octane-1-sulfonic acid sodium salt. Quantitative determination by densitometry in the range of 200-800 nm with a diode array scanner. The LOD and LOQ were 33, 54, 93, 119, 87, 31, 59 and 99, 164, 281, 362, 263, 95, 179 ng/zone for E 102, E 104, E 122, E 124, E 129, E 131, and E133, respectively. The correlation coefficients were 0.9970, 0.9963, 0.9895, 0.9965, 0.9930, 0.9975, and 0.9920, respectively. The linearity was given in the range of 2.5-40 and 2.5-70 µg/mL.