Search Results (24)

This paper provides an overview of thin-layer chromatography (TLC) and high-performance thin-layer chromatography (HPTLC) methods for analyzing plant materials and herbal formulations, as described in scientific publications from January 2022 to July 2025. It describes the use of TLC in the qualitative and quantitative examination of plant materials and pharmaceutical preparations containing herbs, including profiling plant materials using TLC and applying it to HPTLC plates. It also describes other modern methods that improve component separations, such as applying TLC to profile plant formulations and detect adulterations and contaminants in them. Additionally, it discusses TLC coupled with other methods, such as principal component analysis (PCA), hierarchical cluster analysis (HCA), orthogonal partial least squares discriminant analysis (OPLS-DA), mass spectrometry (MS), nuclear magnetic resonance (NMR), surface-enhanced Raman spectroscopy (SERS), and image analysis (IA). The quantitative determination of biologically active compounds in herbs and herbal formulations is presented based on methods that combine TLC with densitometry. The paper also discusses TLC with effect-oriented analysis, including the detection of antimicrobial, antioxidant, enzyme-inhibiting, endocrine-disrupting, genotoxic, and cytotoxic substances. The advantages, disadvantages, and prospects of analyzing plant material using the TLC technique are indicated. TLC/HPTLC has great prospects for use by regulatory authorities due to the low cost of analysis and high throughput. Full article

A new TLC method combined with densitometry was developed for the determination of donepezil hydrochloride in Cogiton Biofarm and Donecept Actavis tablets. The analyses were performed on TLC silica gel 60F₂₅₄ plates with mobile phase of n-butanol + n-propanol + acetone + water + glacial acetic acid at ratio of 2:2:1:1:1, v/v. The proposed mobile phase is miscible and after development the chromatographic plate has a homogeneous background in visible light. Densitometric analysis at λ = 319 nm was used for quantitative studies. The method was linear from 1.0 to 5.0 µg/spot and from 0.2 to 1.0 µg/spot and it was validated for both concentration ranges. The presented method is rapid, selective, linear, accurate, precise, robust, and economical. The results of the donepezil content in drugs calculated from both calibration curves were that no statistically significant differences were observed. The obtained content of donepezil in Cogiton (99.2%) and Donecept (99.0%) tablets is within the deviations permitted by the European Pharmacopoeia in relation to the amount declared by the manufacturer. The novelty of the study consists of the development of chromatographic conditions allowing the separation of as many as six donepezil degradation products with the simultaneous use of TLC chromatographic plates. As a result, the proposed method is economical, since it is several times cheaper than using HPTLC plates. While Ali et al. separated a maximum of three degradation products from donepezil, Pandey et al. successfully separated only two donepezil-related substances from donepezil. The proposed new TLC method combined with densitometry can be used for the routine control of donepezil in pharmaceutical preparations (tablets). Since TLC is less sensitive and precise compared to HPLC, it can be used as a complementary technique. Full article

TLC (thin-layer chromatography) and HPTLC (high-performance thin-layer chromatography) in normal (NP) and reversed (RP) phase systems were combined with densitometry to analyze caffeine, propyphenazone, and paracetamol. This work aims to check whether comparable limit of detection (LOD) values can be obtained on TLC and HPTLC plates. Analyses were performed on five (NP) or four (RP) different stationary phases (chromatographic plates), testing, in both cases, three mobile phases. It is shown that by using both TLC and HPTLC plates, it is possible to develop chromatographic conditions that enable the detection of compounds analyzed in amounts ranging from a dozen to several dozen µg/spot. In the RP system, lower LOD values for all tested compounds were obtained using TLC than HPTLC. However, performing analyses in the NP, similar (of the same order) LOD values were obtained for caffeine, propyphenazone, and paracetamol when using both TLC and HPTLC plates. For example, during the NP-HPTLC analysis using silica gel 60F₂₅₄ plates (#1.05548) and mobile phase B (n-hexane—acetone—ammonia, 25:25:0.5, v/v/v), LOD values for caffeine, propyphenazone, and paracetamol were 0.010, 0.046, and 0.030 μg/spot, respectively. During NP-TLC analysis using silica gel 60F₂₅₄ (#1.05554 plates) and the mobile phase C (chloroform—toluene—ethyl acetate—methanol—80% acetic acid, 18:18:7.5:6:0.3, v/v), the values of LOD were 0.054, 0.029, and 0.016 μg/spot, respectively. During RP-TLC analysis using TLC RP-18F₂₅₄ plates (#1.05559) and mobile phase F (methanol-water, 40:10, v/v), the LOD values were 0.019, 0.024, and 0.053 μg/spot, respectively. Therefore, for economical reasons, TLC plates should be recommended for analyses of caffeine, propyphenazone, and paracetamol, which are several times cheaper than HPTLC plates. Full article

The food supplement market is growing as many consumers wish to complement their nutrient intake. Despite all the regulations in place to ensure food supplements safety, there are still many cases of irregularities reported especially connected to internet sales. Twenty resveratrol food supplement products sold on the Slovenian market were evaluated on their compliance of declared vs. determined resveratrol content, as well as the compliance of labels with the European Union (EU) and Slovenian regulatory requirements. Both the ingredient contents and food information are important parts of food safety. Analyses of 20 food supplements performed using high-performance thin-layer chromatography (HPTLC) coupled with densitometry showed that 95% of products had contents different from what was declared and 55% of products contained higher contents than declared. In 25% of the products the determined content per unit exceeded the maximum level (150 mg/day) specified in EU novel food conditions for food supplement with trans-resveratrol. Evaluation of the 20 food supplement labels included mandatory and voluntary food information, food supplement information, novel food information, health claims and nutrition claims. Most labels contained the necessary information, but multiple errors were observed ranging from typos to misleading practices. From a food safety perspective there is still a lot of improvement needed in the field of food supplements. Full article

The literature on ecofriendly/greener high-performance thin-layer chromatographic (HPTLC) methods for quantifying flufenamic acid (FFA) is scant. In order to develop and validate a stability-indicating greener HPTLC densitometry assay for FFA determination in marketed products, this research was conducted. The ecofriendly eluent system was composed of ethanol–water (70:30 v/v). FFA was measured at 290 nm of wavelength. The greenness scale of suggested analytical assay was derived using “Analytical GREENness (AGREE)” methodology. The suggested stability-indicating HPTLC assay was linear for FFA determination in 25–1400 ng/band range with a determination coefficient of 0.9974. The suggested analytical assay for FFA analysis was simple, rapid, accurate, precise, robust, selective, stability-indicating, and greener. The AGREE scale for the developed stability-indicating HPTLC assay was derived to be 0.77 utilizing AGREE methodology, indicating an outstanding greenness characteristic of the suggested densitometry technique. The ecofriendly HPTLC technique was able to detect FFA degradation product under forced degradation studies, indicating its stability-indication characteristics and selectivity. The amount of FFA in marketed tablets brand A and B was determined to be 101.28 and 99.17%, respectively, indicating the suitability of the suggested analytical technique in the assay of FFA in marketed products. These results indicated that FFA in marketed products may be routinely measured using the stability-indicating greener HPTLC technique. Full article

The question of whether exosome lipids can be considered as potential cancer biomarkers faces our current limited knowledge of their composition. This is due to the difficulty in isolating pure exosomes, the variability of the biological sources from which they are extracted, and the uncertainty of the methods for lipid characterization. Here, we present a procedure to isolate exosomes and obtain a deep, repeatable, and rapid phospholipid (PL) composition of their lipid extracts, from embryonic murine fibroblasts (NIH-3T3 cell line) and none (B16-F1) and high (B16-F10) metastatic murine skin melanoma cells. The analytical method is based on High Performance Thin-Layer Chromatography with Ultraviolet and fluorescence densitometry and coupled to Electrospray (ESI)-tandem Mass Spectrometry (MS). Under the conditions described in this work, separation and determination of PL classes, (sphingomyelins, SM; phosphatidylcholines, PC; phosphatidylserines, PS; and phosphatidylethanolamines, PE) were achieved, expressed as µg PL/100 µg exosome protein, obtained by bicinchoninic acid assay (BCA). A detailed structural characterization of molecular species of each PL class was performed by simultaneous positive and negative ESI-MS and MS/MS directly from the chromatographic plate, thanks to an elution-based interface. Full article

Ciprofloxacin is one of the most prescribed antibiotics in treating bacterial infections, becoming an important pollutant of the wastewaters. Moreover, ciprofloxacin is hard to be destroyed by conventional water treatment processes; therefore, efficient treatments to destroy it are needed in water decontamination. This study offers insights into the performance of 266 nm laser beams on the photodegradation of ciprofloxacin. An Nd:YAG laser was used that emitted 266 nm at an energy of 6.5 mJ (power of 65 mW) and ciprofloxacin water solutions were irradiated up to 240 min. The irradiated solutions were investigated by UV-Vis and FTIR absorption spectroscopy, pH assay, and laser-induced fluorescence. An HPTLC densitometer was used to characterize the laser-induced fluorescence and fluorescence lifetime of photodegradation products. The UV-Vis absorption, FTIR, and laser-induced fluorescence spectra showed the degradation of ciprofloxacin. Moreover, HPTLC densitometry offered the fluorescence and fluorescence lifetime of ciprofloxacin and its three photoproducts as well as their relative quantification. From the FTIR spectra, the molecular structure of two out of three photoproducts was proposed. In conclusion, the laser irradiation method provided the efficient photodegradation of ciprofloxacin, whereas the analytical techniques offered the proper means to monitor the process and detect the obtained photoproducts. Full article

Flavan-3-ols and proanthocyanidins of invasive alien plants Japanese knotweed (Fallopia japonica Houtt.), giant knotweed (Fallopia sachalinensis F. Schmidt) and Bohemian knotweed (Fallopia × bohemica (Chrtek & Chrtkova) J.P. Bailey) were investigated using high performance thin-layer chromatography (HPTLC) coupled to densitometry, image analysis and mass spectrometry (HPTLC–MS/MS). (+)-Catechin, (−)-epicatechin, (−)-epicatechin gallate and procyanidin B2 were found in rhizomes of these three species, and for the first time in Bohemian knotweed. (−)-Epicatechin gallate, procyanidin B1, procyanidin B2 and procyanidin C1 were found in giant knotweed rhizomes for the first time. Rhizomes of Bohemian and giant knotweed have the same chemical profiles of proanthocyanidins with respect to the degree of polymerization and with respect to gallates. Japanese and Bohemian knotweed have equal chromatographic fingerprint profiles with the additional peak not present in giant knotweed. Within the individual species giant knotweed rhizomes and leaves have the most similar fingerprints, while the fingerprints of Japanese and Bohemian knotweed rhizomes have additional peaks not found in leaves. Rhizomes of all three species proved to be a rich source of proanthocyanidins, with the highest content in Japanese and the lowest in Bohemian knotweed (based on the total peak areas). The contents of monomers in Japanese, Bohemian and giant knotweed rhizomes were 2.99 kg/t of dry mass (DM), 1.52 kg/t DM, 2.36 kg/t DM, respectively, while the contents of dimers were 2.81 kg/t DM, 1.09 kg/t DM, 2.17 kg/t DM, respectively. All B-type proanthocyanidins from monomers to decamers (monomers—flavan-3-ols, dimers, trimers, tetramers, pentamers, hexamers, heptamers, octamers, nonamers and decamers) and some of their gallates (monomer gallates, dimer gallates, dimer digallates, trimer gallates, tetramer gallates, pentamer gallates and hexamer gallates) were identified in rhizomes of Bohemian knotweed and giant knotweed. Pentamer gallates, hexamers, hexamer gallates, nonamers and decamers were identified for the first time in this study in Bohemian and giant knotweed rhizomes. Full article

Due to unavailability of sustainable analytical techniques for the quantitation of piperine (PPN) in food and pharmaceutical samples, there was a need to develop a rapid and sensitive sustainable analytical technique for the quantitation of PPN. Therefore, the current research presents a fast and highly sensitive normal/reversed-phase high-performance thin-layer chromatography (HPTLC) technique with classical univariate calibration for the quantitation of PPN in various food spices of black pepper with traditional (TE) and ultrasound-assisted extracts (UBE) of various food spices of Piper nigrum L. under green analytical chemistry viewpoint. The amount of PPN in TE of four different spices of black pepper—namely BPMH, BPLU, BPSH, and BPPA—was found to be 309.53, 304.97, 282.82, and 232.73 mg g⁻¹, respectively using a sustainable normal-phase HPTLC technique. However, the amount of PPN in UBE of BPMH, BPLU, BPSH, and BPPA was recorded as 318.52, 314.60, 292.41, and 241.82 mg g⁻¹, respectively using a sustainable normal phase HPTLC technique. The greenness of normal/reversed-phase HPTLC technique was predicted using AGREE metric approach. The eco-scale was found to be 0.90, suggested excellent greenness of normal/reversed-phase technique. UBE of PPN was also found to be superior over TE of PPN. Overall, the results of this research suggested that the proposed normal/reversed-phase densitometry technique could be effectively used for the quantitation of PPN in food and pharmaceutical samples. Full article

The antioxidant activities of Japanese knotweed rhizome bark extracts, prepared with eight different solvents or solvent mixtures (water, methanol, 80% methanol_(aq), acetone, 70% acetone_(aq), ethanol, 70% ethanol_(aq), and 90% ethyl acetate_(aq)), were determined using a 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical-scavenging assay. Low half maximal inhibitory concentration (IC₅₀) values (2.632–3.720 µg mL⁻¹) for all the extracts were in the range of the IC₅₀ value of the known antioxidant ascorbic acid at t₀ (3.115 µg mL⁻¹). Due to the highest extraction yield (~44%), 70% ethanol_(aq) was selected for the preparation of the extract for further investigations. The IC₅₀ value calculated for its antioxidant activity remained stable for at least 14 days, while the IC₅₀ of ascorbic acid increased over time. The stability study showed that the container material was of great importance for the light-protected storage of the ascorbic acid_(aq) solution in a refrigerator. Size exclusion–high-performance liquid chromatography (SEC-HPLC)–UV and reversed phase (RP)-HPLC-UV coupled with multistage mass spectrometry (MSⁿ) were developed for fractionation of the 70% ethanol_(aq) extract and for further compound identification, respectively. In the most potent antioxidant SEC fraction, determined using an on-line post-column SEC-HPLC-DPPH assay, epicatechin, resveratrol malonyl hexoside, and its in-source fragments (resveratrol and resveratrol acetyl hexoside) were tentatively identified by RP-HPLC-MSⁿ. Moreover, epicatechin was additionally confirmed by two orthogonal methods, SEC-HPLC-UV and high-performance thin-layer chromatography (HPTLC) coupled with densitometry. Finally, the latter technique enabled the identification of (−)-epicatechin. (−)-Epicatechin demonstrated potent and stable time-dependent antioxidant activity (IC₅₀ value ~1.5 µg mL⁻¹) for at least 14 days. Full article

Invasive alien plant species Canadian goldenrod (Solidago canadensis L.) and giant goldenrod (Solidago gigantea Aiton) were investigated as a source of phytochemicals and yellow dyes. Flavonoids and phenolic acids were extracted from the inflorescence of Canadian goldenrod with thirteen extraction solvents ethanol, methanol, acetone, water, and mixtures of organic solvents (70%, 80%, and 90%) with water. High performance thin-layer chromatography (HPTLC) coupled to densitometry and high-performance liquid chromatography with photo-diode array detector (HPLC-PDA) were used for analyses of the obtained sample test solutions (STSs), which showed the best and comparable extraction efficiencies for 70% acetone_(aq), 70% methanol_(aq), and 70% ethanol_(aq). HPTLC combined with image analyses in fluorescent mode resulted in different chromatographic fingerprints for Canadian goldenrod and giant goldenrod STSs (70% acetone_(aq)) after development, after post-chromatographic derivatization with NP reagent and after use of PEG reagent. The developed HPLC methods enabled analyses of phenolic acids and flavonoids (aglycones and glycosylated) in STSs and hydrolyzed STSs form inflorescence of Canadian and giant goldenrod. Different contents of chlorogenic acid, rutin, hyperoside, isoquercetin, and quercetin were observed in STSs of both goldenrod species. The analyses of hydrolyzed STSs confirmed that glycosylated flavonoids in Canadian and giant goldenrod inflorescence are mainly glycosides of quercetin, kaempferol, and isorhamnetin. Additional analyses using HPTLC and HPLC coupled to tandem mass spectrometry (MS/MS; HPTLC-MS/MS and LC-MS/MS) enabled tentative identification of phenolic acids and flavonoids (10 with HPTLC-MS/MS and 15 with LC-MS/MS), from which several were identified in Canadian (4 with HPTLC-MS/MS and 8 with LC-MS/MS) and in giant (7 with HPTLC-MS/MS and 9 with LC-MS/MS) goldenrod for the first time. Full article

Anthraquinones (yellow dyes) were extracted from Japanese knotweed rhizomes with twelve extraction solvents (water; ethanol_(aq) (20%, 40%, 60%, 70% and 80%), ethanol, 70% methanol_(aq), methanol, 70% acetone_(aq), acetone and dichloromethane). The obtained sample test solutions (STSs) were analyzed using high-performance thin-layer chromatography (HPTLC) coupled to densitometry and mass spectrometry (HPTLC–MS/MS) on HPTLC silica gel plates. Identical qualitative densitometric profiles (with anthraquinone aglycones and glycosylated anthraquinones) were obtained for STSs in all the solvents except for the STS in dichloromethane, which enabled the most selective extractions of anthraquinone aglycones emodin and physcion. The highest extraction efficiency, evaluated by comparison of the total peak areas in the densitograms of all STSs scanned at 442 nm, was achieved for 70% acetone_(aq). In STS prepared with 70% acetone_(aq), the separation of non-glycosylated and glycosylated anthraquinones was achieved with developing solvents toluene–acetone–formic acid (6:6:1, 3:6:1 and 3:3:1 v/v) and dichloromethane–acetone–formic acid (1:1:0.1, v/v). Non-glycosylated anthraquinones were separated only with toluene–acetone–formic acid, among which the best resolution between emodin and physcion gave the ratio 6:6:1 (v/v). This solvent and dichloromethane–acetone–formic acid (1:1:0.1, v/v) enabled the best separation of glycosylated anthraquinones. Four HPTLC-MS/MS methods enabled the identification of emodin and tentative identification of its three glycosylated analogs (emodin-8-O-hexoside, emodin-O-acetyl-hexoside and emodin-O-malonyl-hexoside), while only the HPTLC-MS/MS method with toluene-acetone-formic acid (6:6:1, v/v) enabled the identification of physcion. Changes of the shapes and the absorption maxima (bathochromic shifts) in the absorption spectra after post-chromatographic derivatization provided additional proof for the detection of physcion and rejection of the presence of chrysophanol in STS. Full article

Due to the lack of ecofriendly/green reversed-phase high-performance thin-layer chromatography (RP-HPTLC) methods for trans-anethole (TAL) and its simplicity over routine analytical techniques, there was a necessity to establish a suitable HPTLC methodology for the quantitative analysis of TAL. Therefore, the first objective of this research was to develop an accurate, rapid and green RP-HPTLC densitometry methodology for the quantitative analysis of TAL in essential oil, traditional and ultrasound-assisted extracts of Foeniculum vulgare Mill and commercial formulations. The second objective was to compare the traditional method of extraction of TAL with its ultrasound-assisted method of extraction. The chromatogram of TAL from essential oil and traditional and ultrasound-assisted extracts of fennel and commercial formulations was verified by recoding its single spectra at R_f = 0.31 ± 0.01 in comparison to standard TAL. The proposed analytical methodology has been found to be superior in terms of linearity, accuracy and precision compared to most of the reported analytical methods for TAL analysis. The amount of TAL in the essential oil of fennel was recorded as 8.82 mg per g of oil. The content of TAL in traditional extracts of fennel, formulation 1 (dietary supplement 1) and formulation 2 (dietary supplement 2), was recorded as 6.44, 4.88 and 4.48 mg per g, respectively. The amount of TAL in ultrasound-assisted extracts of fennel, formulation 1 and formulation 2, was recorded as 8.34, 6.46 and 5.81 mg per g, respectively. The ultrasound method of extraction of TAL was found to be better than the traditional method of extraction. The results of validation studies and phytochemical analysis showed that the proposed methodology could be efficiently utilized for the quantification of TAL in the wide range of products having TAL as a component. Full article

Various analytical methodologies have been reported for the determination of 6-shogaol (6-SHO) and 6-gingerol (6-GIN) in ginger extracts and commercial formulations. However, green analytical methods for the determination of 6-SHO and 6-GIN, either alone or in combination, have not yet been reported in literature. Hence, the present study was aimed to develop a rapid, simple, and cheaper green reversed phase high-performance thin-layer chromatography (RP-HPTLC) densitometry method for the simultaneous determination of 6-SHO and 6-GIN in the traditional and ultrasonication-assisted extracts of ginger rhizome, commercial ginger powder, commercial capsules, and commercial ginger teas. The simultaneous analysis of 6-SHO and 6-GIN was carried out via RP-18 silica gel 60 F254S HPTLC plates. The mixture of green solvents, i.e., ethanol:water (6.5:3.5 v/v) was utilized as a mobile phase for the simultaneous analysis of 6-SHO and 6-GIN. The analysis of 6-SHO and 6-GIN was performed at λ_max = 200 nm for 6-SHO and 6-GIN. The densitograms of 6-SHO and 6-GIN from traditional and ultrasonication-assisted extracts of ginger rhizome, commercial ginger powder, commercial capsules, and commercial ginger teas were verified by obtaining their single band at R_f = 0.36 ± 0.01 for 6-SHO and R_f = 0.53 ± 0.01 for 6-GIN, compared to standard 6-SHO and 6-GIN. The green RP-HPTLC method was found to be linear, in the range of 100–700 ng/band with R² = 0.9988 for 6-SHO and 50–600 ng/band with R² = 0.9995 for 6-GIN. In addition, the method was recorded as “accurate, precise, robust and sensitive” for the simultaneous quantification of 6-SHO and 6-GIN in traditional and ultrasonication-assisted extracts of ginger rhizome, commercial ginger powder, commercial capsules, and commercial ginger teas. The amount of 6-SHO in traditional extracts of ginger rhizome, commercial ginger powder, commercial capsules, and commercial ginger teas was obtained as 12.1, 17.9, 10.5, and 9.6 mg/g of extract, respectively. However, the amount of 6-SHO in ultrasonication-assisted extracts of ginger rhizome, commercial ginger powder, commercial capsules, and commercial ginger teas were obtained as 14.6, 19.7, 11.6, and 10.7 mg/g of extract, respectively. The amount of 6-GIN in traditional extracts of ginger rhizome, commercial ginger powder, commercial capsules, and commercial ginger teas were found as 10.2, 15.1, 7.3, and 6.9 mg/g of extract, respectively. However, the amount of 6-GIN in ultrasonication-assisted extracts of ginger rhizome, commercial ginger powder, commercial capsules, and commercial ginger teas were obtained as 12.7, 17.8, 8.8, and 7.9 mg/g of extract, respectively. Overall, the results of this study indicated that the proposed analytical technique could be effectively used for the simultaneous quantification of 6-SHO and 6-GIN in a wide range of plant extracts and commercial formulations. Full article

The purpose of the work was to develop such chromatographic conditions that allowed to separate as many naproxen degradation products as possible. In order to follow this process, thin-layer chromatography (TLC) coupled with densitometry and spectrodensitometry was used. A forced degradation study was performed using an ethanolic solution of naproxen spotted on silica gel plates, existing in the form of an aqueous solution at various pH values, and as solution prepared in saline and in hydrogen peroxide. Degradative effect of UV light on naproxen was watched in the context of naproxen spotted on plates precoated with silica gel and exposed to UV light, and also for its solution treated with UV light. However, the solution of naproxen prepared in water at pH ≈ 2.60 undergoes the largest changes as the results of its exposure to UV light during 10 h. Stressed samples of naproxen were analyzed by using a new and well validated TLC procedure including toluene (TOL)—acetone (ACE)—chloroform (CHL) (2:5:12, v/v/v) as mobile phase A and glacial acetic acid (AcOH)—n-hexane (Hex)—acetone (ACE)-(0.10:10:10, v/v/v) as mobile phase B. As the newly developed TLC-densitometric method can effectively separate the substances about pharmaceutical significance from products of its degradation, which are formed as a result of stress studies, is considered to be a good alternative and important tool in routine quality control and stability testing of naproxen in pharmaceutical formulations. These results indicate that proposed TLC-densitometric method is cost-effective, rapid, specific, accurate, and precise. This TLC procedure is comparable to HPLC and UPLC method in terms of detection the number of degradation products of naproxen. In addition, it realizes the criterion of linearity. A major advantage and novelty of proposed method is its low cost and ability to analyze examined drug and all degradation products simultaneously, including those which can be observed under intensive UV radiation exposure of naproxen solution which are not described by previous HPTLC studies available in the literature. Full article