J. Planar Chromatogr. 31, 129-134 (2018). HPTLC of hydroxysafflor yellow A in safflower on silica gel with 3.6 % hydrochloric acid – methanol – ethyl acetate 7:3:1. Quantitative determination by absorbance measurement at 399 nm. The hRf value for hydroxysafflor yellow A was 60. Linearity (starting from LOD) was in the range of 62-793 ng/zone with r=0.9991. The intermediate precision was below 3 % (n=6). The LOD and LOQ were 59 and 169 ng/zone, respectively. Recovery was between 96 and 102 %.

J. Liq. Chromatogr. Relat. Technol. 41, 373-376 (2018). HPTLC of 22 amino acids in the cultures of control and starved Biomphalaria glabrata snails on cellulose plates with 2-butanol – pyridine – acetic acid – water 39:34:10:26. Detection by spraying with 2 % ninhydrin solution in n-butanol – acetone 1:1, followed by heating at 110 ºC for 10 min. Quantitative determination by absorbance measurement at 610 nm. Samples were also analyzed on RP-18 with water – methanol 3:7 with addition of 100 mM formic acid in the bonded phase normal phase mode and water – methanol 7:3 with the addition of 100 mM trifluoroacetic acid in the bonded phase reversed phase mode. Although better separation results were obtained with the cellulose plates, an excellent separation of the pair Ile and Leu with the RP-18 W was noted.

J. Liq. Chromatogr. Relat. Technol. 31, 203-222 (2018). HPTLC of fluorometholone (1) and sodium cromoglycate (2) on silica gel with ethyl acetate – methanol 9:1. Quantitative determination by absorbance measurement at 240 nm. The hRf values for (1) and (2) were 65 and 12, respectively. Linearity was in the range of 0.1-24.0 μg/zone for (1) and 0.2-48.0 μg/zone for (2). The intermediate precision was below 1.1 % (n=9). The LOD and LOQ were 9 and 270 ng for (1) and 170 and 510 ng for (2), respectively. Average recoveries for (1) and (2) were 100.3 and 100.7 %, respectively.

J. AOAC Int. 101, 1437-1447 (2018). Micro-TLC of 18 standard dyes (Amaranth, Bromophenol blue, Bromothymol blue, Patent blue V, p-Xylenol blue, Brilliant Black BN, Erythrosine, Fluorescein, Carmine, Naphthalene black 10B, Phenol red, Bromocresol purple, Sudan II, Sudan III, Sudan IV, Bromocresol green, Dimethyl yellow, and Methyl red) on silica and cellulose with different solvent mixtures (methanol – water and dichloromethane – methanol) in proportions varying from 0 to 100 %. Chromatographic parameters and quantum mechanics properties of each solute were used along with data mining to model the chromatographic behavior.

methanolic fraction. J. Planar Chromatogr. 31, 327-331 (2018). HPTLC of caffeic acid (1), vanillic acid (2), and syringic acid (3) in O. corniculata L. methanolic fraction on silica gel with toluene ‒ ethyl acetate ‒ formic acid 7:3:1. Quantitative determination by absorbance measurement at 300 nm. The hRF values for (1) to (3) were 36, 44 and 54, respectively. Linearity ranged between 100-700 ng/zone. LOD and LOQ were 40 and 100 ng /zone, respectively. The intermediate precision was <2 % (n=3). Recovery was between 97.1 and 99.6 %.

J. Ethnopharmacol. 232, 135-144 (2019). HPTLC of hesperidin in Citrus reticulatae pericarpium on silica gel with ethyl acetate – formic acid – acetic acid – water 15:1:1:2. Qualitative identification at UV 275 nm. The hRF value for hesperidin was 26.

J. AOAC Int. 101, 385-393 (2018). HPTLC of nifuroxazide and its impurities A, B, C and D on silica gel with ethyl acetate – acetone – methanol – ammonia 170:50:10:1. Quantitative determination by absorbance measurement at 230 nm. The hRF values for nifuroxazide and its impurities A, B, C and D were 67, 46, 86, 8 and 34, respectively. Linearity ranged between 10-100 μg/zone for nifuroxazide and 0.1-1.0 μg/zone for impurities A to D. LOD and LOQ were 28 and 84 ng/zone for A, 27 and 80 ng/zone for B, 24 and 73 ng/zone for C and 26 and 79 ng/zone for D. The intermediate precision was <1 % (n=3). Average recovery was 100.5 % for nifuroxazide, 100.2 % for A, 99.0 % for B, 100.0 % for C and 100.2 % for D.

J. Planar Chromatogr. 31, 272-279 (2018). HPTLC of chlorpheniramine (1), pseudoephedrine (2), and ibuprofen (3) on silica gel with ethyl acetate ‒ methanol ‒ ammonia 20:5:2. Quantitative determination by absorbance measurement at 262 nm. The hRF values for (1) to (3) were 78, 64 and 29, respectively. Linearity was between 0.2 and 9 μg/zone for (1), 2 and 30 μg/zone for (2), and 5 and 50 μg/zone for (3). LOD and LOQ were 72 and 218 ng/zone for (1), 285 and 864 ng/zone for (2), and 1004 and 3042 ng/zone for (3), respectively. The intermediate precision was <2 % (n=3). Average recovery was 100.5 % for (1), 100.9 % for (2) and 100.7 % for (3).