J. Liq. Chromatogr. Relat. Technol. https://doi.org/10.1080/10826076.2021.1932521 (2021). HPTLC of gallic acid in the stem bark of Schinus terebinthifolius on silica gel with toluene - ethyl acetate - formic acid - methanol 15:15:4:1. The plates were scanned at 254 nm and 366 nm. The hRF value for gallic acid was 43. Image features were acquired using a combination of two approaches: Haralick texture features and Zernike moments. The GNU OctaveVR software was used to set the architectures of the Artificial Neural Network. The mathematical data provided by the image analysis was correlated with the gallic acid content determined by HPLC. The method allowed the prediction of phenolic content through TLC plate images.

J. Liq. Chromatogr. Relat. Technol. https://doi.org/10.1080/10826076.2021.1930556 (2021). HPTLC of patulin in apple juice on silica gel with methyl tert-butylether - n-pentane 9:5. Detection by spraying with 0.25 % methyl-benzothiazolinone hydrazone hydrochloride monohydrate in methanol, followed by heating at 105 °C. Quantification was performed using a 48-bit flatbed scanner for color measurements (in red, green, and blue). Quantification in fluorescence mode by use of a 16-bit CCD-camera and UV-366 nm illumination as well as a HPTLC DAD-scanner. The hRF value for patulin was 58. Linearity was between 5 and 800 ng/zone. The LOD and LOQ were 33 and 67 ng/zone, respectively.

J. Liq. Chromatogr. Relat. Technol. https://doi.org/10.1080/10826076.2021.1930555 (2021). HPTLC of ofloxacin (1), tinidazole (2), terbinafine hydrochloride (3), and clobetasol propionate (4) on silica gel with toluene - ethyl acetate - methanol - triethylamine - formic acid 50:40:10:3:3. Quantitative determination by absorbance measurement at 238 nm. Linearity was between 300 and 1500 ng/zone for (1) to (4). The intermediate precision was below 2 % (n=6). Recovery was between 98.9 and 99.1 % for (1), 98.9 and 99.3 % for (2), 99.0 and 99.5 % for (3) and 98.9 and 99.3 % for (4).

J. Liq. Chromatogr. Relat. Technol. https://doi.org/10.1080/10826076.2021.1939046 (2021). HPTLC of picroside-I (1), andrographolide (2) and silybin (3) in Picrorhiza kurroa (roots), Andrographis paniculata (aerial parts) and Silybum marianum (seeds), respectively, on silica gel with n-butanol - glacial acetic acid - water 6:1:3. Quantitative determination by absorbance measurement at 254 nm. The hRF values for (1) to (3) were 49, 68 and 89, respectively. Linearity was between 60 and 600 ng/zone for (1) to (3). The intermediate precision was below 2 %. The LOD and LOQ were 15 and 45 ng/zone for (1), 22 and 67 ng/zone for (2) and 26 and 78 ng/zone for (3), respectively. Recovery was between 99.7 and 103.7 % for (1), 99.7 and 101.1 % for (2) and 99.0 and 101.7 % for (3).

Sci. Agropecu. 12, 161-168 (2021). HPTLC of annonacin in the leaves of soursop (Annona muricata) and microencapsulated extract on silica gel with chloroform - cyclohexane - diethylamine 2:1:1. Quantitative determination by absorbance measurement at 210 nm. 

Anal. Bioanal. Chem. 410, 5641-5661 (2018). HPTLC of eight Sudan dyes, i.e., Sudan I (1), Sudan II (2), Sudan (3), Sudan IV (4), Sudan Red B (5), Sudan Red 7B (6), Sudan Orange G (7), and Para Red (8) in chili powder, paprika powder, curcuma powder, chili sauce, curry paste, palm oil on caffeine-impregnated silica gel with isohexane - ethyl methyl ketone 5:1. Densitometric evaluation in absorption mode at 390, 415, 500, 525, and 550 nm. Zones of interest were eluted with the oval elution head of the TLC-MS interface for further mass spectrometry analysis. The hRF values for (1) to (8) were 44, 48, 29, 33, 33, 38, 22 and 20, respectively. The LOD and LOQ were 2 and 9 ng/zone for (1) to (8), respectively. Recovery was between 73 and 120 %.

Anal. Bioanal. Chem. 412, 6431-6448 (2020). Hydrophilic interaction high-performance
thin-layer chromatography (HI-HPTLC) of Stevia leaf extracts and 20 different food products on silica gel with acetonitrile - water 4:1. Detection by spraying with 2-naphthol sulfuric acid reagent (2 g in 180 mL ethanol plus dropwise 8 mL 50 % sulfuric acid) followed by heating at 160 ºC for 2 min, primuline reagent (0.1 g in 40 mL water plus 160 mL acetone), followed by documentation at 366 nm or anisaldehyde sulfuric acid reagent (1 mL 4-methoxybenzaldehyde, 8 mL sulfuric acid, 16 mL glacial acetic acid and 140 mL methanol), followed by heating at 110 ºC for 5 min. Quantitative determination by absorbance measurement at 500 nm after derivatization with the 2-naphthol sulfuric acid reagent and at 366/> 400 nm after derivatization with primuline reagent. Full scan mass spectra (m/z 100–1500) were recorded via heated electrospray ionization (HESI) in the positive and negative ionization mode. Bioprofiling and effect-directed detections were performed using a Gram-negative A. fischeri bioassay, Gram-positive B. subtilis bioassay, β-glucuronidase assay, tyrosinase assay, α-glucosidase assay, AChE assay and DPPH assay. 

Anal. Bioanal. Chem. 411, 6655-6665 (2019). HPTLC of lovastatin present in lactone (1) and hydroxy acid forms (2) and mycotoxin citrinin (3) in red yeast rice on silica gel with n-hexane - acetone - 10 % acetic acid 60:40:1. Quantitative determination by absorbance measurement at 238 nm for (1) and (2) and fluorescence measurement at 313/> 400 nm for (3). The hRF values for (1) to (3) were 35, 23 and 7, respectively. Linearity was between 50 and 500 ng/zone for (1) and (2) and 5 and 50 ng/zone for (3). Intermediate precision was below 2 % (n=5). The LOD and LOQ were 10 and 50 ng/zone for (1) and (2) and 1 and 4 ng/zone for (3). Average recovery was 109.9 % for (1) to (3).