J. Planar Chromatogr. 29, 330-335 (2016). HPTLC of wedelactone in Eclipta alba, Wedelia calendulacea and Wedelia trilobata on silica gel with toluene – chloroform – ethanol – formic acid 10:8:2:1. Quantitative determination by absorbance measurement at 351 nm. The hRF value for wedelactone was 29. Linearity was between 80 and 280 ng/zone. The intermediate precision was below 2.5 % (n=3). The LOD and LOQ was 0.36 and 1.09 ng/zone, respectively. Recoveries were between 99.4 and 100.3 %.

J. Planar Chromatogr. 29, 388-390 (2016). HPTLC of dimethoate from post mortem viscera on silica gel with hexane - acetone 4:1. Detection by spraying with freshly prepared sodium nitroprusside solution (1 % sodium nitroprusside in 2 N sodium hydroxide solution prepared with especially sulfide-free distilled water). The hRF value for dimethoate was 88.

J. Planar Chromatogr. 30, 154-163 (2017). HPTLC of chlorpyrifos (1), quinalphos_x000D_ (2), and triazophos (3) on silica gel with n-hexane ‒ acetone 9:1 and on RP-18 with acetonitrile ‒ water 4:1. The results indicated that the hRf values of all three pesticides increased with the polarity of the solvent.

J. Chromatogr. Sci. 54 (7), 1090-1095 (2016). Comparison of the dynamics of peptidization of L-serine (L-Ser), an important proteinogenic amino acid which undergoes spontaneous oscillatory processes of chiral inversion and peptidization with D-Ser and DL-Ser (racemate). The main analytical techniques used in the experiment were TLC-densitometry, HPLC–evaporative light scattering detector and LC–MS. The results showed the differences in peptidization dynamics of the two Ser enantiomers (L and D) and of the racemic mixture thereof (DL) and showed that DL-Ser characterizes with the higher, and L- and D-Ser with the lower peptidization yields.

J. Chromatogr. Sci. 54 (9), 1661-1669 (2016). Development of two sensitive and accurate stability-indicating chromatographic methods for the determination of rafoxanide (RFX): 1) by TLC on silica gel with chloroform – ethyl acetate – toluene – ammonia 50:40:3:1, determination by densitometry at 280 nm; 2) by UPLC. Identification of the degradation products by mass spectrometry and IR spectroscopy. Both proposed methods proved to be accurate, robust, specific and suitable for application as stability-indicating methods for routine analysis of RFX in quality control laboratories.

J. Planar Chromatogr. 30, 405-410 (2017). HPTLC of 200 hydrocarbons containing condensed aromatic rings on silica gel with n-hexane and n-heptane. A magnetic field at constant inductivity (0.44 T), generated by a pair of permanent magnets perpendicular to the direction of chromatogram development was used to investigate its influence in the retention of substances.

CBS 118, 1-4 (2017). Screening of steroids and selective androgen receptor modulators (SARMs) in bodybuilding supplements by HPTLC of methanedienone, ibutamoren, and ostarine on silica gel with n-heptane – ethyl acetate 1:1 (steroids) and dichloromethane – methanol 9:1 (SARMs) to the migration distance of 70 mm. Detection by immersion into (1) toluene sulfonic acid reagent (10 % in ethanol) followed by heating at 150 °C for 3 min, or (2) Seebach reagent (5 g phosphomolybdic acid, 2 g cerium sulfate and 12 mL sulfuric acid made up to a volume of 200 mL with water) followed by heating at 110 °C for 5 min. Detection under UV 254 nm, 366 nm and under white light. Densitometric evaluation by multi-wavelength scan at the respective absorption maxima. For example for the steroid testosterone the LOD was 8 ng/zone (absorbance measurement at 250 nm). Direct elution of target zones into the MS and analysis in positive ionization mode.

J. Chromatogr. Sci. 55, 961-968 (2017). Presentation of two accurate, precise and highly selective stability-indicating methods for simultaneous determination of benztropine mesylate (BNZ) in presence of its hepatotoxic and carcinogenic degradation product, benzophenone (BPH) either in pure form or in the pharmaceutical formulation without any preliminary separation steps. TLC of BNZ and its degradation product on silica gel with hexane – methylene chloride – triethylamine 25:25:3. Quantitative determination by densitometry at 235 nm. The linearity was between 1.5-10 μg/band and 1-10 μg/band for BNZ and BPH, respectively. UPLC of the mixture on a RP C8 analytical column, quantification using a diode array detector at 210 nm. The linearity with UPLC was 20-200 μg/mL and 5-50 μg/mL for BNZ and BPH, respectively. Comparison of the results showed no significant differences between the TLC and UPLC method regarding both accuracy and precision.