J. Planar Chromatogr. 34, 197-202 (2021). HPTLC of L‑proline (1) and L‑lysine (2) derivatives on silica gel with ethanol - toluene 2:3 in a horizontal chamber. Amino acids pre-chromatographic derivatization with 2-propanol - phenyl isothiocyanate - phosphate buffer pH 12 7:1:1. Detection by spraying with a solution of 4 % sodium azide, 0.5 % starch, pH 5.5, followed by exposure to iodine vapor for 20 s. Plates were scanned with an office scanner and the zones were converted to peaks by software. The hRF values for (1) and (2) were 32 and 67, respectively. Intermediate precisions were below 9 % (n=6). The LOD was 0.05 nmol/zone for (1) and 0.05 nmol/zone for (2). Recovery was between 94 and 104 % for (1) and 82 and 104 % for (2).

J. Planar Chromatogr. 34, 229-242 (2021). HPTLC of chlorthalidone (1) and metoprolol succinate (2) on silica gel with toluene - methanol - triethylamine 16:4:1. Quantitative determination by absorbance measurement at 230 nm. The hRF values for (1) and (2) were 44 and 23. Linearity was between 200 and 1000 ng/zone for (1) and 800 and 4000 ng/zone for (2). Intermediate precisions were below 2 %. The LOD and LOQ were 29 and 88 ng/zone for (1) and 151 and 459 ng/zone for (2), respectively. Recovery was between 99.9 and 100.9 % for (1) and 100.4 and 101.6 % for (2).

J. Planar Chromatogr. 34, 279-283 (2021). HPTLC of linagliptin on silica gel with toluene - methanol 7:3. Quantitative determination by absorbance measurement at 294 nm. The hRF value for linagliptin was 91. Linearity was between 100 and 500 ng/zone. Intermediate precisions were below 2 % (n=3). The LOD and LOQ were 0.26 and 0.78 ng/zone, respectively. Recovery was between 99.1 % and 101.2 %.

J. Planar Chromatogr. 34, 243-252 (2021). HPTLC of dapagliflozin (1) and metformin (2) on silica gel with methanol - ethyl acetate - ammonium acetate 60:40:1. Quantitative determination by absorbance measurement at 220 nm. The hRF values for (1) and (2) were 79 and 31, respectively. Linearity was between 20 and 100 ng/zone for (1) and 500 and 2500 ng/zone for (2), respectively. Intermediate precisions were below 2 % (n=5). The LOD and LOQ were 3 and 10 ng/zone for (1) and 11 and 34 ng/zone for (2), respectively. Recovery was between 100.0 % and 101.6 % for (1) and 99.7 % and 101.1 % for (2).

Revista Bio Ciencias. 6, 670 (2019). HPTLC of the leaves of Turnera diffusa on silica gel with ethyl acetate - acetic acid - formic acid - water 100:11:11:27. Detection by spraying with 1 % 2-aminoethyl diphenyl borate in methanol (NP) and with 5 % polyethylene glycol 4000 in ethanol (PEG). Qualitative analysis under UV light at 254 and 366 nm.

Phytochem. Anal. 33, 83-93 (2022). HPTLC of table olives (Olea europaea) on silica gel with dichloromethane - methanol - acetic acid 45:5:1. Detection by spraying with sulfuric vanillin reagent (5 % vanillin in methanol - 5 % sulfuric acid in methanol 1:1) and under UV light at 254 and 366 nm. Further analysis by nuclear magnetic resonance. 

Phytochem. Anal. 33, 115-126 (2022). HPTLC bioautography of 14 Egyptian plants on silica gel with methylene chloride - methanol 9:1 (system I) or ethyl acetate - methanol - water - glacial acetic acid 120:20:16:1 (system II). Detection by spraying with anisaldehyde/sulfuric acid reagent. Aromatase inhibitory assay was performed by dipping into 112.5 mL cofactor solution (containing 4.5 mL of 0.5 % sodium phosphate buffer, 4.5 mL NADPH regenerating system solution A and 0.9 mL NADPH regenerating system solution B and then completed to volume with distilled water), followed by incubation at 37 °C for half an hour, then re-immersed in 75 mL aromatase E/S mix (containing 120 μL aromatase enzyme, 0.03 mL DBF and 3 mL albumin dissolved in 0.075 M potassium phosphate buffer) and re-incubated for another half an hour. Enzymatic reaction was terminated by immersing plates into 2N sodium hydroxide stop solution. Active zones were observed under UV 366 nm. Calculation of the inhibition zones was performed by reciprocal iso-inhibition volume (RIV) that is based on measuring the zone pixel intensity. The hRF values for chrysin were 63 and 91 in systems I and II, respectivley. The intermediate precision was below 3 % (n=3). Linearity was between 0.1 and 0.3 μg/zone. LOD and LOQ were 80 and 206 ng/zone, respectively. Recovery was between 92.5 and 106.5 %. Two quantification methods, the peak area and RIV method were compared and the RIV method showed superiority over the peak area method with %RSD values of 0.98 and 1.49 compared with 2.86 and 3.58, respectively.

J. of Chromatogr. Sci., 59 (10) 909-922 (2021). Development of a green stability indicating method for the quantitative determination of tenofovir alafenamide and its by-products produced under stress conditions. HPTLC on silica gel with n-butanol - acetic acid 7:3 and detection at 260 nm. Beer’ law was obeyed over the concentration range of 0.1- 4 μg/zone. Also micellar UPLC method. Both methods are validated according to ICH guidelines and successfully applied to the analysis of the drug in its tablets. In addition, their greenness was assessed using three different tools indicating their least hazardous effect on the environment.