J Chrom Sci, bmad042 (2023). Standards (separated and mixed) were antazoline (ANT) and tetryzoline (TET) hydrochlorides. Samples were one commercial ophthalmic solution containing both molecules (unspiked and spiked), and aqueous humour of untreated rabbits as biological fluid, spiked with various concentrations of ANT and TET. TLC on silica gel with ethyl acetate – ethanol 1:1. Visualization under UV 254 nm. Densitometric absorbance measurement at 220 nm (20mm/s scanning speed). The hRF was 47 for TET and 71 for ANT. System suitability was verified by resolution, selectivity, capacity and absence of tailing. The method was validated for linearity range (0.2 – 18 µg/band), for precision, for reproducibility, for robustness, and for accuracy expressed as average recovery values (100 % overall mean) at different concentrations. The method was also found statistically equivalent (Student’s t-test and F-test) to the official corresponding titrimetric methods of the European Pharmacopoeia. Finally, environmental and health impacts of the methods were qualitatively and quantitatively assessed better as the other described methods, using analytical greenness (AGREE), green analytical procedure index (GAPI), national environmental method index (NEMI), and analytical eco-scale (scores based on solvents/reagents, energy consumption, occupational hazard and waste generation).

Marine Drugs 20(4), 270 (2022). Samples were ether glycerols (EG) purified: (A) from Chimaera monstrosa liver oil (Chimaeridae); (B) from mixed liver oil of sharks Centrophorus squamosus (Centrophoridae) and Somniosus microcephalus (Somniosidae); (C) from Macaca fascicularis hearts (Cercopithecidae); (D) from tumors obtained by grafting in mice the human melanoma cell line MDA-MB-435s, and (E) from periprostatic adipose tissue of men with prostate cancer. Reduction of (phospho)ester glycerolipids into EG and fatty alcohols was part of the purification process. Octadecyl-glycerol and octadecenyl-glycerol were used as standards of alkyl- and alkenyl-glycerols, respectively. HPTLC on silica gel previously developed with chloroform – methanol 1:1, air-dried and activated for 30 min at 110° C. Application under nitrogen stream (6 bar). Development with petroleum ether – diethyl ether – acetic acid 60:140:1. After 2 h drying at room temperature under ventilation hood, visualization by 50 s immersing into sulfuric acid (7 % in ethanol), followed by 2 h drying under air-stream, and 14 min heating at 140° C. Plates were documented under white light illumination and densitometry was performed by computered scanning of the pictures. Alkyl-glycerols (mean hRF 34, LOQ 1235 ng/band) and alkenyl-glycerols (mean hRF 44, LOQ 2352 ng/band), present in all samples (except alkenyl-glycerols in shark oil), were quantified after method validation for specificity, sensitivity, accuracy, precision and repeatability. Linearity range was 1000 ng – 7000 ng for both EG types. To confirm the band identification, samples and standards were also submitted to acidic hydrolysis before HPTLC application. In this case, the bands of alkenyl glycerols did not appear, because chlorhydric acid reacted with the vinyl ether bonds to form glycerol and aldehydes.

J Chromatogr A 1638, 461895 (2021). Samples were sphingolipid-rich fractions of unproteinated blood plasma from healthy humans or from Fabry’s disease patients, as well as standards of sphingomyelin (SM) and of globotriaosylceramides (Gb3 = ceramide trihexosides), and related compounds (lyso-ceramide trihexosides, lactosyl ceramide, glucosyl ceramide). HPTLC on silica gel (Lichrosphere with spherical particles) by automated multiple development with a 9-step gradient, starting with pure methanol and ending with dichloromethane – methanol 9:1. Visualization and densitometry under UV 190 nm. Derivatization for Gb3 and derivatives (but not for SM) by immersion into orcinol solution (0.2 %, with sulfuric acid 10 %), followed by 15 min heating at 100 °C and by densitometry under visible light 550 nm. Bands of interest were directly eluted with methanol from underivatized plates into an ion-trap MS, through the oval head of a TLC-MS interface (with stainless steel frit to remove silica gel particles). Two different ionization processes were used: (A) electrospray ionization (ESI, capillary voltage 4 kV, endplate offset voltage -0.5 kV, nebulizer pressure 40 psi, drying gas 9 mL/min at 350 °C); (B) atmospheric pressure chemical ionization (APCI, capillary voltage 2–3 kV, current intensity 4.5 µA, nebulizer pressure 45 psi, drying gas 5 mL/min at 350 °C; vaporization at 450 °C). Full MS spectra were recorded up to m/z 1500 in positive ion mode. The relative ion intensities were used to quantify the detected species. Previous to this study, the precision of the elution head positioning was tested on Gb3 standard zones, comparing 3 positions for analyte elution: from the centre and from each higher or lower side of the band. The same main m/z peaks were observed in the 3 positions, but in different proportions. This was explained by the presence of coeluting Gb3 subclasses (the ceramide moiety CM being either saturated, mono-unsaturated fatty acyl with a slightly higher migration distance, or polar hydroxyl fatty acyl with the opposite effect on migration) and of coeluting Gb3 isoforms (the hexoside moiety consisting of glucose and/or galactose units). This resulted in the broadening and partial splitting of the standard band. In the plasma samples, 19 molecular species of Gb3 were identified (depending on the CM, the sugar isoforms being undistinguishable by MS): 5 with a saturated CM, 7 with two additional double bonds on the CM, 7 with a methylated CM. In case of Fabry’s disease, most Gb3 species with saturated CM were highly increased, whereas other species were decreased.

J. Sep. Sci. 45, 3800-3810 (2022). HPTLC of favipiravir (1) and meropenem (2) in human plasma on silica gel with ethyl acetate - methanol - water - formic acid 50:40:15:3. Quantitative determination by absorbance measurement at 300 nm for (1) and (2). The hRF values for (1) and (2) were 34 and 10, respectively. Linearity was between 0.1 and 20 µg/mL for (1) and 10 and 60 µg/mL for (2). Inter-day and intra-day precisions were below 5 % (n=3). The LOQ were 0.1 and 10 µg/mL for (1) and (2), respectively. Mean recovery was 99.7 % for (1) and 98.0 % for (2).

J. Planar Chromatogr. 33, 419-425 (2020). Immunochromatography of cannabinoids (1) and opiates (2) in human urine using a test cassette device consisting of five parts, including a plastic backing, sample pad, conjugate pad, absorbent pad, and nitrocellulose (NC) membrane. Visual LOD was 50 ng/mL for (1) and 300 mg/mL for (2). Recovery was between 98 and 111 % for (1) and 101 and 110 % for (2).

J Herpetol 51(4), 538-551 (2017). HPTLC of retinyl palmitate (1), retinal (2), and of retinal oxime with all trans, syn (3) and anti (4) isomers, on silica gel with cyclohexane – toluene – ethyl acetate 5:3:2 in a twin-trough chamber. Evaluation under white light and at UV 254 nm and after spraying with Carr–Price reagent (saturated solution of SbCl3 in chloroform). The hRF values of (1), (2), (3), and (4) were 84, 55, 44, and 24, respectively.

Quantification by scanning fluorometry at 350 nm, excitation and 450 nm emission after exposure to formic acid vapor. Recovery 94.7-107.2 %. The method is suitable for clinical assay and pharmacokinetic study.

J. Chromatogr. 436, 73-79 (1988). Two-dimensional TLC on silica with dichloromethane - acetone - 25% NH3 100:100:5 for the first dimension and butanol - acetic acid - water 8:2:10 for the 2nd. Identification under UV 254 nm and 366 nm.