Food Res. Int. 111, 361-370 (2018). HPTLC of triacylglycerols in unfermented and fermented cocoa beans on silica gel with hexane – diethyl ether – glacial acetic acid 80:20:1 and then with chloroform – methanol – glacial acetic acid 97:3:1. Detection by spraying with cerium molybdate reagent. Direct comparison of fermented and unfermented beans revealed the absence of cacaoic acid at hRf 55._x000D_

CBS 120, 14-15 (2018). The drugs cefixime trihydrate (CEFI) and azithromycin dihydrate (AZI) were subjected to hydrolytic degradation (with water, 0.5 N HCl or 0.5 N NaOH), oxidative degradation (with 3 % and 30 % hydrogen peroxide), thermal degradation (heated at 100 °C and 200 °C for 1 h and 2 h) and photolytic degradation (exposed to fluorescent cold white light and UV light). HPTLC of CEFI, AZI, and the degradation samples on silica gel with ethyl acetate – methanol – acetone –_x000D_ toluene – ammonia 2:10:14:1:1 to the migration distance of 80 mm. Detection of AZI by immersion into sulfuric acid reagent (1:4 in ethanol) and heating at 100 °C for 5 min. Evaluation under UV 254 nm, UV 366 nm, and white light. Quantitative determination by absorbance measurement at 235 nm for CEFI and 530 nm for AZI. Linearity was in the range of 500–2500 ng/zone for CEFI and 50–250 ng/zone for AZI. The LOD and LOQ (ng/zone) for CEFI were 58 and 175, respectively, and for AZI 3 and 10, respectively. Precision (%RSD) was <2 %. In the forced degradation studies, CEFI degraded to 4 major products under different stress conditions. AZI showed only one additional peak upon acid and neutral hydrolysis.

J. Liq. Chromatogr. Relat. Technol. 41, 364-372 (2018). TLC-DPPH test of gluten-free sheeted pasta supplemented with pomegranate seeds powder (PSP) on silica gel with ethyl acetate – water – acetic acid 8:1:1. Plates were immersed for 5 s in a freshly prepared 0.1 % methanolic DPPH solution and scanned every 10 min over an hour. The total areas under the peaks per track were measured and compared with the area obtained for rutin. Antioxidant properties of gluten free pasta correlated with the PSP content.

J. Chromatogr. A 1534, 179-187 (2018). Investigation of the influence of pH of the mobile phase buffer on retention of peptides in both normal phase (NP) and reversed phase (RP) HPTLC systems with C18 silica-based adsorbent as the solid phase. Comparison of the influence of pH on retention and/or migration distance of peptides in separation systems of HPTLC and pressurized planar electrochromatography (PPEC) techniques. It was found that the change of pH of the mobile phase buffer can be used for two-dimensional HPTLC separation of peptides, but much stronger change of separation selectivity can be achieved by overall inversion of separation system type (NP/RP). Influence of the mobile phase pH on selectivity of peptide separation in PPEC is different than that in HPTLC, due to the significant share of electrophoretic effect in mechanism of separation and better selectivity of separation by PPEC, however the change of pH affects the efficiency of the separation system in both techniques, so it can be used for optimization of separation conditions. Discussion of some modifications of PPEC equipment and materials useful for application of this technique in the field of peptide analysis.

Pharmacogn. Mag. 14, 437-443 (2018). HPTLC fingerprinting of 7 plant species from northeast Brazil (Anacardium occidentale, Annona muricata, Guazuma ulmifolia, Phyllanthus niruri, Psidium guajava, Punica granatum, and Spondias mombin) using caffeic acid (1), quercetin (2), gallic acid (3) and catechin (4) as chemical markers on silica gel with toluene – ethyl acetate – methanol – formic acid 85% 75:25:25:6. Detection of (1) and (2) by spraying with natural products reagent A + 5 % polyethylene glycol 400. Detection of (3) and (4) by spraying with ferric chloride and vanillin-HCl, respectively. Qualitative evaluation under UV light at 254 and 365 nm. The hRF values for (1), (2) and (4) in Anacardium occidentale were 30, 42 and 21, respectively. The hRF value for (4) in Annona muricata was 16. The hRF values for (1) and (4) in Guazuma ulmifolia were 44 and 20, respectivley. The hRF values for (1) and (4) in Psidium guajava were 3 and 18, respectively. The hRF value for (1) in Punica granatum was 33. The hRF values for (1) to (4) in Spondias mombin were 31, 43, 31 and 17, respectively.

leaves. J. Planar Chromatogr. 31, 377-381 (2018). HPTLC of ursolic acid and β-sitosterol in the leaves of Paederia foetida on silica gel with toluene ‒ ethyl acetate ‒ formic acid 80:20:1. Detection by spraying with anisaldehyde–sulfuric acid reagent, followed by heating at 110 °C for 1 min. Quantitative determination by absorbance measurement at 550 nm. The hRF values for (1) and (2) were 22 and 38, respectively. Linearity was between 100 and 500 ng for (1) and (2). LOD and LOQ were 40 and 121 ng for (1) and 50 and 152 ng for (2). The intermediate precision was <2 % (n=3). Recovery ranged from 97.2 % to 99.2 % for (1) and 98.0 % to 99.2 % for (2).

J. AOAC Int. 101, 1397-1401 (2018). HPTLC of sudan red dyes, namely Sudan orange G (1), Sudan red G (2), Sudan I (3), Sudan II (4), Sudan III (5) and Sudan IV (6) in spices and spice mixtures on RP-18 acetonitrile – methanol – aqueous ammonia solution (25 %) 40:9:1. Quantitative determination using a flatbed scanner with a 16-bit resolution. The hRF values for (1) to (6) were 54, 48, 57, 35, 26 and 17, respectively. Linearity was between 20 and 500 ng/zone for (1) to (6). LOD and LOQ were 17 and 35 ng/zone for (1), 11 and 21 ng/zone for (2), 14 and 31 ng/zone for (3), 12 and 24 ng/zone for (4), 18 and 42 ng/zone for (5) and 16 and 37 ng/zone for (6), respectively.

J. Planar Chromatogr. 31, 361-365 (2018). TLC of (±)-terbutaline on silica gel with chiral ligand-exchange reagent (LER). L-(‒)-Trp, L-(‒)-Phe, and L-(‒)-His were chosen as chiral selectors. Copper(II) acetate (2 mM) and L-amino acid (4 mM) solutions were prepared in water ‒ methanol 17:1 and mixed to be used as LER. In terms of resolution, best enantioseparation was obtained with acetonitrile ‒ methanol ‒ chloroform ‒ water 10:4:3:3 using L-Trp as chiral selector. The hRF values for (-) and (+)-isomers were 20 and 56, respectively.