J. of Chromatogr. A 1441, 126-133 (2016). Presentation of a method for the analysis of ergot alkaloids including an ammonium acetate buffered extraction step, followed by a fast liquid-liquid partitioning pre-cleaning and then planar solid phase extraction (pSPE). HPTLC on amino phase with methanol for separation of the ergot alkaloids from the remaining matrix and for focusing them in a single zone. Quantification after dipping the plate in n-hexane – paraffin solution for fluorescence enhancement. The LOD and LOQ was 0.07 and 0.24 mg/kg rye, respectively, expressed as ergocristine, which was well below the currently applied quality criteria limit for rye. The recovery was almost 100 % at relevant spiking levels for different rye flour samples. The pSPE–FLD method was fast, efficient and reliable for screening the total ergot alkaloid content in rye and it was a rapid alternative to the HPLC determination with summing up the individual alkaloids. Furthermore, HPTLC-MS additionally enables the identification of the ergot alkaloid composition by a single mass spectrum, when utilized as a fingerprint, offering an easy differentiation of Secale cornutum from different origins.

J. Liq. Chromatogr. Relat. Technol. 40, 287-291 (2017). HPTLC of hypericin on silica gel with ethyl acetate – water – formic acid – t-butyl methyl ether – cyclohexane 90:7:7:40:15. Chemiluminescence was used for detection by dipping into bis(2,4,6-trichlorophenyl)oxalate (TCPO) reagent for 1 s, prepared by dissolving 250 mg TCPO in 36 mL of n-butyl acetate, plus added 0.4 mL of 35 % hydrogen peroxide vigorously shaken for 20 min. A sensitive CCD camera was used to measure the chemiluminescence. The hRF value for hypercin was 27. LOD and LOQ were 440 and 690 pg/zone, respectively.

J. Planar Chromatogr. 30, 193-198 (2017). HPTLC of 20-hydroxyecdysone in Sesuvium portulacastrum on silica gel with chloroform – methanol – benzene 25:5:3. Quantitative determination by absorbance measurement at 254 nm. The hRF value for 20-hydroxyecdysone was 30. Linearity was between 50 and 500 ng/zone. LOD and LOQ were 4 and 14 ng/zone. The intermediate precision was below 2 % (n=6). The recovery rate ranged from 98.6 to 102.4 %.

J. Planar Chromatogr. 30, 285-290 (2017). HPTLC of cefazolin sodium on silica gel with water – ethanol 3:7. Detection by exposure to iodine vapor in an iodine saturated chamber for 15 min. Quantitative determination after scanning the plate and using the free and open-source image editor GIMP 2.8. The hRF value for cefazolin was 83. Linearity was between 1 and 5 mg/mL. The intermediate precision (n=6) was <2 %. Average recovery rate was 100 %.

J. Ethnopharmacol. 213, 230-255 (2018). Review of the botany, ethnopharmacology, phytochemistry, biological activities, nutritional value, possible molecular mechanisms, safety and clinical applications of Morinda officinalis with a special focus on its bioactivities, including the application of HPTLC for the analysis of oligosaccharides from different habitats.

Food Chem. 243, 258-268 (2018). HPTLC of [6]-gingerol (1) and [6]-shogaol (2) in 17 ginger rhizomes and ginger-containing food products on silica gel with n-hexane – ethyl acetate 13:7. Detection by dipping into anisaldehyde sulfuric acid reagent (5 mL concentrated sulfuric acid was added to a mixture of 500 μL anisaldehyde, 10 mL acetic acid and 100 mL methanol), followed by heating at 110 °C for 5 min. Quantitative determination by absorbance measurement at 580 nm. The hRF values for (1) and (2) were 32 and 41, respectively. LOD and LOQ were 25 and 45 ng/zone for (1) and 20 and 40 ng/zone for (2), respectively. The primuline reagent (100 mg primuline in 200 mL acetone – water 4:1) was also investigated for detection, but it was not as sensitive. Polynomial calibrations ranged between 0.9982 and 0.9999. Their contents ranged 0.2–7.4 mg/g (1) and 0.2–3.0 mg/g (2) in the different products. Intermediate precisions were mostly ≤8 % for (1) and ≤10 % for (2) in the different food matrices. Effect-directed detection was performed via A. fischeri and B. subtilis bioassays, tyrosinase and AChE inhibition assays and DPPH* radical scavenging assay. Active unknown zones were further characterized by HPTLC-ESI-HRMS and assigned as [8]-gingerol and [10]-gingerol. Among others, further multi-detected zones were assigned to be [4]-gingerol, dehydro-[6]-gingerdione, dehydro-[6]-gingerol, dehydro-[8]-gingerol, dehydro-[10]-gingerol etc.

J. Planar Chromatogr. 31, 72-78 (2018). HPTLC of equol in ethanolic cattle manure extract on RP-18 with n-hexane – ethyl – acetate – acetone 9:3:2. Detection by planar yeast estrogen screening (pYES) by dipping into a yeast suspension, followed by incubation at 30 °C for 4 h. After incubation, the plate was dried in a 37 °C incubator for 15 min and dipped into the combined reaction buffer followed by incubation at 37 °C for 60 min and 90 % relative humidity. The combined reaction buffer was prepared by mixing 20 mL of buffer C (5.3 g of sodium phosphate dibasic and 0.4 g of potassium chloride were dissolved in about 490 mL water, the solution was adjusted with sodium hydroxide to pH 13, 0.5 g of benzalkonium chloride were added and the mixture was filled up to 500 mL) and 0.2 mL of a freshly prepared X-Gal solution (0.05 g/mL X-Gal in DMSO). Fluorescence evaluation under UV 366 nm. The hRF value for equol was 47.

J. Planar Chromatogr. 31, 213-219 (2018). HPTLC of β-sitosterol in the leaves of five Ficus species (F. carica, F. nitida, F. ingens, F. palmata, and F. vasta) on silica gel with ethyl – acetate 4:1. Detection by spraying with p-anisaldehyde reagent followed by drying. Quantitative determination by absorbance measurement at 550 nm. The hRf value for β-sitosterol was 17. Linearity was in the range of 100-1400 ng/zone. The intermediate precision was below 2 % (n=6). The LOD and LOQ were 32 and 98 ng/zone, respectively. Recovery was between 98.5 and 99.7 %.