J. of Chromatogr. Sci. 59 (6), 536-547 (2021). HPTLC of pregabalin (PGB) and amitriptyline (AMT) as an active binary mixture in pure forms or in human biological fluids (plasma/urine)  on silica gel with ethanol - ethyl acetate - acetone - ammonia solution 160:40:20:1. Detection by spraying with 3 % ethanolic ninhydrin solution. Quantitative determination by densitometry at 220 nm for AMT and 550 nm for PGB peaks after derivatization. The linearity range was 0.2 - 2.5 μg/band for PGB and 0.1-2.0 μg/band for AMT.

J. of Chromatogr. Sci. 59(5), 425–431 (2021). HPTLC of bromhexine hydrochloride (BHX), impurity B (IMB) and impurity C (IMC) on silica gel with hexane - acetone - ammonia solution 450:25:4. Quantitative determination by densitometry at 240 nm. The linearity was in the range of 0.40-10.00, 0.20-2.00 and 0.20-2.00 μg/band for BHX, IMB and IMC, respectively. Comparison with an HPLC method showed no significant differences regarding accuracy and precision.

J. of Chromatogr. Sci. 59 (2), 140-147 (2021). TLC of paracetamol (PC), propyphenazone (PZ) and caffeine (CF) in the presence of the two PC impurities 4-aminophenol and 4-nitrophenol, on silica gel with chloroform - toluene - ethyl acetate - methanol - acetic acid 60:60:10:20:1. Quantitative determination by densitometry at 220 nm.

J. of Chromatogr. Sci. 58 (6), 520 – 534 (2020). HPTLC of 10-hydroxy-2-decenoic acid (10-HDA) in royal jelly products marketed in Egypt, on silica gel with chloroform - acetic acid 10:1. Quantitative determination by densitometry at 210 nm. First and second derivative treatment of the data and comparison between three statistical regression methods: parametric, nonparametric and weighted regression (WR). Derivative treatment of the data improved the sensitivity of the chromatographic signals. The WR method was advantageous over the use of the other two models and resulted in an enhancement of the accuracy and precision of the 10-HDA analysis. Recovery was 99.9 % with WR and 99.6 and 98.6 % with the other statistical methods. Further, the royal jelly standard was subjected to forced degradation studies including the effect of hydrolysis, oxidation, photolysis and dry heat.

J. of Chromatogr. Sci. 58 (5), 427 - 432 (2020). HPTLC of ulipristal acetate (UPA) in presence of its degradation products on silica gel with ethyl acetate - toluene - glacial acetic acid 40:70:3. UPA was subjected to acid and alkali hydrolysis, oxidation, photo and thermal degradation. The hRF of UPA was 38. Quantitative determination by densitometry. The linearity range was between 400-3600 ng/band. LOD was 72 ng/band and LOQ 220 ng/band. The recovery was 100.1-100.7 %. The method is accurate, precise, robust, and specific to measure UPA in presence of degradants.

Quim. Nova. 43, 878-883 (2020). HPTLC of caryophyllene (1) and the diterpenic acids copalic (2), hydroxy-copalic (3), acetoxycopalic (4), agathic (5), and hardwickiic (6) in oilresin of Copaifera on silica gel with hexane - ethyl acetate 7:3. Detection by spraying with ethanol in 10 % sulfuric acid, followed by heating for 5 min. Qualitative analysis at 366 nm. The hRF values for (1) to (6) were 80, 50, 8, 28, 16 and 40, respectively.

Biochem. Biophys. Res. Commun. 534, 1069-1075 (2021). HPTLC of gangliosides in human and mouse siglecs on silica gel with chloroform - methanol - 0.2 % calcium chloride 60:25:4. Immunostaining by dipping into cyclohexane containing 0.1 % poly (isobutyl methacrylate) for 1 min, blocked by incubation in PBS containing 1 % BSA at room temperature for 1 h, incubated with premixture of Sig7EcFc WT or R124A and anti-hIgG + M + A-HRP in PBS containing 0.1 % BSA or S2-566 (anti-diSia antibody) in PBS containing 1 % BSA at room temperature for 2 h, and washed 5 times with PBS. Horseradish peroxidase activity was detected by chemiluminescence. Sig7EcFc corresponds to extracellular domain of Siglec-7 fused to the human IgG1 Fc region.

Biochem. Biophys. Res. Commun. 536, 73-79 (2021). HPTLC of ceramide dihexosides (lactosylceramide and its structural isomer, galabiosylceramide) in human cerebrospinal fluid on silica gel with chloroform - methanol - water 65:25:3. Detection by spraying with orcinol reagent, followed by heating at 120 ºC for 10 min.