Showing papers on "Thin-layer chromatography published in 2005"
94 citations
TL;DR: In this paper, a suppression of silanophilic interactions by the selected ionic liquids added to the mobile phase in thin-layer chromatography and high-performance liquid chromatography (HPLC) is reported.
89 citations
TL;DR: Dry tetrahydrofuran (THF), toluene, benzene, dichloromethane, methanol, N,N-dimethylformamide (DMF), and triethylamine were obtained by passing these previously degassed solvents through activated alumina columns and calibrated using residual undeuterated solvent as an internal reference.
Abstract: General procedures. All reactions were carried out under an inert nitrogen atmosphere with dry solvents under anhydrous conditions unless otherwise stated. Dry tetrahydrofuran (THF), toluene, benzene, dichloromethane (CH2Cl2), methanol (MeOH), N,N-dimethylformamide (DMF), and triethylamine (Et3N) were obtained by passing these previously degassed solvents through activated alumina columns. Reagents were purchased at the highest commercial quality and used without further purification, unless otherwise stated. Copper(I) iodide was freshly purified from refluxing saturated aqueous NaI solution (aqueous). Yields refer to chromatographically and spectroscopically (H NMR) homogeneous materials, unless otherwise stated. Reactions were monitored by thin layer chromatography (TLC) carried out on 0.25 mm E. Merck silica gel plates (60F-254) using UV light as the visualizing agent and an acidic mixture of anisaldehyde or phosphomolybdic acid or basic aqueous potassium permangante (KMnO4) and heat as developing agents. E. Merck silica gel (60, particle size 0.043–0.063 mm) was used for flash column chromatography. Preparative thin layer chromatography (PTLC) separations were carried out on 0.25 or 0.5 mm E. Merck silica gel plates (60F-254). NMR spectra were recorded on Bruker DRX-600, DRX-500, and AMX-400 or Varian Inova-400 instruments and calibrated using residual undeuterated solvent as an internal reference. The following abbreviations were used to explain the multiplicities: s = singlet, d = doublet, t = triplet, q = quartet, m = multiplet, b = broad. High-resolution mass spectra (HRMS) were recorded on Agilent LC/MSD TOF time-of-flight mass spectrometer by electrospray ionization time of flight reflectron experiments. IR spectra were recorded on a Perkin Elmer Spectrum BX FTIR spectrometer. Melting points were recorded on a Fisher-Johns 12-144 melting point apparatus.
58 citations
27 Jan 2005
50 citations
TL;DR: Methods for induction of callus and cell suspension cultures have been developed for the medicinally important herb Centella asiatica (L.) Urban and thin layer chromatography and high performance liquid chromatography analysis showed the presence ofAsiaticoside in the in vitro grown leaves, callus or cell suspension cultured cells.
Abstract: Methods for induction of callus and cell suspension cultures have been developed for the medicinally important herb Centella asiatica (L.) Urban. Thin layer chromatography (TLC) and high performance liquid chromatography (HPLC) analysis showed the presence of asiaticoside in the in vitro grown leaves, callus and cell suspension cultured cells.
43 citations
TL;DR: A method using a thin layer chromatography for compound-specific stable carbon isotope analysis of polycyclic aromatic hydrocarbons with four to seven rings with silica gel is superior to aluminum oxide and thesilica gel precoated plate developed with hexane:chloroform can give the best separation effect.
32 citations
TL;DR: Silica gel thin-layer chromatography plates impregnated with macrocyclic antibiotic, vancomycin, as chiral selector were used for the resolution of (+/-)-verapamil and the detection limit was found to be 0.074 microg of each enantiomers.
Abstract: Silica gel thin-layer chromatography plates impregnated with macrocyclic antibiotic, vancomycin, as chiral selector were prepared and used for the resolution of (±)-verapamil. A mobile phase system of acetonitrile–methanol–water (15:2.5:2.5, v/v) was worked out systematically. The effects of chiral selector, temperature and pH on resolution were also studied. The spots were detected with iodine vapors and the detection limit was found to be 0.074 µg of each enantiomers. Copyright © 2005 John Wiley & Sons, Ltd.
29 citations
TL;DR: In this article, the authors used thin-layer chromatography (TLC) and high-performance liquid chromatography to detect sulfonylurea-type oral antidiabetic agents (OADs), tolbutamide (TOL), acetohexamide (ACE), chlorpropamide (CHL), gliclazide (GLC), glibenclamide (GLB), and glimepiride (GLM), in adulterated health food.
Abstract: Screening and quantitative analysis for six sulfonylurea-type oral antidiabetic agents (SU-OADs), tolbutamide (TOL), acetohexamide (ACE), chlorpropamide (CHL), gliclazide (GLC), glibenclamide (GLB), and glimepiride (GLM), in adulterated health food has been developed. The SU-OADs were extracted with acetone and then the extract was subjected to thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC). In the TLC analysis, good separation was achieved with a mixture of n-butyl acetate containing 0.4% formic acid as a solvent. Ultraviolet irradiation at 254 nm was used to detect the SU-OADs. Specificity was obtained with Dragendorff's test solution, 10% phosphomolybdic acid methanol solution, and 30% sulfuric acid methanol solution. On the other hand, with a gradient reverse-phase HPLC system equipped with a photodiode array detector, we were able to detect the SU-OADs within 15 min using an ODS column and acetonitrile-ammonium acetate buffer as a mobile phase. Quantitative analysis based on HPLC was also performed with the absolute calibration curve method. Recoveries were 90.7-105.2% for the drugs tested. The intra- and interassay relative standard deviations were 0.2-8.1 and 0.6-7.2%, respectively. When the methods were applied to prescription glibenclamide tablets, health food, and spiked samples, good selectivity, separation, recovery, and precision were obtained.
28 citations
TL;DR: In this paper, an intact TLC silica-coated rod (15 cm) was coupled to a GC/MS instrument to obtain the neutral and polar fraction of a lipid extract previously separated by TLC.
26 citations
TL;DR: The proposed HPLC method was utilized to investigate the kinetics of the acidic, alkaline, and oxidative degradation processes at different temperatures and the apparent pseudo-first-order rate constant, half-life, and activation energy were calculated.
Abstract: Two sensitive and reproducible methods are described for the quantitative determination of itopride hydrochloride (IH) in the presence of its degradation products. The first method is based on HPLC separation on a reversed phase Kromasil column [C 18 (5-μm, 25 cm x 4.6 mm, ID)] at ambient temperature using a mobile phase consisting of methanol and water (70:30, v/v) adjusted to pH 4.0 with orthophosphoric acid with UV detection at 258 nm. The flow rate was 1.0 mL per min with an average operating pressure of 180 kg/cm 2 . The second method is based on HPTLC separation on silica gel 60 F 254 using toluene:methanol:chloroform:10% ammonia (5.0:3.0:6.0:0.1, v/v/v/v) as mobile phase at 270 nm. The analysis of variance (ANOVA) and Student's t-test were applied to correlate the results of IH determination in dosage form by means of HPLC and HPTLC methods. The drug was subjected to acid and alkali hydrolysis, oxidation, dry heat, wet heat treatment, UV, and photodegradation. The proposed HPLC method was utilized to investigate the kinetics of the acidic, alkaline, and oxidative degradation processes at different temperatures and the apparent pseudo-first-order rate constant, half-life, and activation energy were calculated. In addition the pH-rate profile of degradation of IH in constant ionic strength buffer solutions in the pH range 2-11 was studied.
22 citations
TL;DR: The behavior of ACE inhibitors and their active degradation products in salting-out thin-layer chromatography (SO TLC) has been examined on silica gel, cellulose, and polyacrylonitrile (PAN) with aqueous ammonium sulfate solutions of different concentration as mobile phases.
Abstract: The behavior of five ACE inhibitors and their active degradation products in salting-out thin-layer chromatography (SO TLC) has been examined on silica gel, cellulose, and polyacrylonitrile (PAN) with aqueous ammonium sulfate solutions of different concentration as mobile phases. It was found that increasing the concentration of the salt in the mobile phase led to increased R M values for all the substances. Linear relationships were established between salt concentration and R M values and regression data of the plots obtained were used to determine the lipophilicity R M 0 and C 0 . Lipophilicity determined in this way was correlated with calculated log P values. For comparison of these results with chromatographic behavior in conventional RP TLC, the examined substances were subjected to thin-layer chromatography on RP-18 silica gel with methanol-water mobile phases.
TL;DR: In this paper, the chromatographic behavior of roxithromycin, midecamycin, erythromycin (midecamcin), azithromycin, azithrombin, and erythyromycin ethylsuccinate has been studied by salting-out thin-layer chromatography (SOTLC) with cellulose as a adsorbent and aqueous ammonium sulfate solutions of different concentration as mobile phases.
Abstract: The chromatographic behavior of roxithromycin, midecamycin, erythromycin, azithromycin, and erythromycin ethylsuccinate has been studied by salting-out thin-layer chromatography (SOTLC) with cellulose as a adsorbent and aqueous ammonium sulfate solutions of different concentration as mobile phases. Hydrophobicity was determined from the linear relationships between solute R M values and the ammonium sulfate content of the mobile phase. Hydrophobicity values R M 0 and C 0 were calculated on the basis of the results obtained. Lipophilicity determined in this way was correlated with calculated log P values.
Journal Article•
TL;DR: The purified antibiotic KL39 was very effective for the biocontrol of in vivo Phytophthora-blight disease of pepper and strongly inhibits the DNA biosynthesis of the fungal cell.
Abstract: Bacillus megaterium KL39, an antibiotic-producing plant growth promoting rhizobacterium (PGPR), was selected from soil The antifungal antibiotic, denoted KL39, was purified from culture filtrate by column chromatography using Dion HP-20, Silica gel, Sephadex LH-20, and prep-HPLC Thin layer chromatography, employing the solvent system of ethanol:ammonia:water=8:1:1, showed the R f value of 032 The antibiotic KL39 showed a negative reaction with ninhydrin solution, positive with iodine vapor, and also positive with Ehrlich reagent It was soluble in methanol, ethanol, butanol, and acetonitrile, but insoluble in chloroform, toluene, hexane, ethyl ether, or acetone Its UV spectrum had the maximum absorption at 208 nm Amino acid composition, FAB-mass, 1 H-NMR, 13 C-NMR, and atomic analyses showed that the antibiotic KL39 (MW=1,071) has a structure very similar to iturin E The antibiotic KL39 has a broad antifungal spectrum against a variety of plant pathogenic fungi including Rhizoctonia solani, Pyricularia oryzae, Monilinia froeticola, Botrytis cinenea, Altenaria kikuchiuna, Fusarium oxysporum, and F solani An MIC value of 10 μg/ml was determined for Phytophthora capsici Macromolecular incorporation studies with P capsici using radioactive [ 3 H-adenine] as the precursor, indicated that the antibiotic KL39 strongly inhibits the DNA biosynthesis of the fungal cell Microscopic observation of the antifungal action showed abnormal hyphal swelling of P capsici The purified antibiotic KL39 was very effective for the biocontrol of in vivo Phytophthora-blight disease of pepper
TL;DR: The history of 60 years of planar chromatography is described in this paper, following the evolution of the technique and focusing on the detection modes, as well as commercially available equipment.
Abstract: The chromatographic techniques using a flat stationary phase and capillary forces to move the mobile phase appeared centuries ago. The paper stationary phase evolved in silica layers on flat surface. The history of 60 years of planar chromatography is told following the evolution of the technique and focusing on the detection modes. The research prototypes are described as well as commercially available equipment. The author concludes by revealing his view of the future of the technique.
TL;DR: The analysis performed in the time interval of 6 to 48 hours after the end of 2-deoxy-2-[18F]FDG synthesis indicated that the activity of the autoradiolysis products separated by HPLC did not exceed 1.3%.
Abstract: To control virtually the toxic compounds and to improve quality control of the solution of 2-deoxy-2-[18F]fluoro-d-glucose (2-[18F]FDG), the products of its autoradiolysis were analyzed by high-performance liquid chromatography with electrospray mass spectrometric and radiometric detectors (HPLC/MS/RAD), thin layer chromatography on TLC silica plate and HPTLC on amino modified silica plate. Except Kryptofix™ 2.2.2, glucose and fluoride anion, no by-products and impurities were observed by LC/MS analysis of fresh 2-[18F]FDG samples. The analysis performed in the time interval of 6 to 48 hours after the end of 2-[18F]FDG synthesis indicated that the activity of the autoradiolysis products separated by HPLC did not exceed 1.3%. As the main autoradiolysis products of 3.3 . 10-5 to 4.4 . 10-5M 2-[18F]FDG solution of original specific activity 0.5-1.5 GBq . cm-3 were established: arabinose - 2.8 μM (G= 0.07/100 eV), gluconic and glucuronic acids 1.8-0.5 μM (G =0.01-0.05/100 eV), arabinose and araburonic acids occurred under 0.5 μM concentration at residual glucose contents about 0.14 mM. Radiation chemical yields of active products were calculated from molar activity of 2-[18F]FDG and the percentage of their activity: 0.5% radiochemical yield of 2-[18F]fluoroglucuronic acid corresponds to the G = 0.004/100 eV and 0.3% yield of 2-[18F]fluorogluconic acid issues G = 0.003/100 eV.
TL;DR: A novel and convenient method based on native polyacrylamide gel electrophoresis (PAGE) and homogenization extraction was used for the purification of xylanase from crude enzymes, indicating that these two xylanases were endo-acting enzymes, designated xyl I and xyl II.
TL;DR: The best efficiency, peak symmetry, and separation selectivity of the investigated compounds is obtained through the addition of amine (especially diethylamine) to the mobile phases.
Abstract: Selected alkaloid standards were chromatographed on C18 W layers using various aqueous eluents containing an organic modifier and pH 3 buffer to suppress silanol ionization or an organic modifier and pH 8 buffer to suppress alkaloid ionization. Anionic ion pairs such as sodium dodecyl sulfate, octane-1-sulfonic acid sodium salt, pentane-1-sulfonic acid sodium salt, and bis(2-ethylhexyl)ortho-phosphoric acid are used to improve peak shape, efficiency, and selectivity. Amines (e.g., diethylamine, triethylamine, and tetrabutylamonium chloride) are incorporated into mobile phases to block surface silanols. The effect of chromatographic conditions on the separation of the investigated alkaloids is analyzed by the comparison of particular densitograms, asymmetry factor, or theoretical plate number. The best efficiency, peak symmetry, and separation selectivity of the investigated compounds is obtained through the addition of amine (especially diethylamine) to the mobile phases.
TL;DR: The utility of the proposed NP HPLC approach was demonstrated by assessment of intra- and inter-batch content uniformity, and by the determination of pac litaxel content after 7 and 60 days exposure of the paclitaxel-loaded polymer matrix to in vitro and in vivo degradation.
TL;DR: In this article, the combined effects of hydrogen and air flow rates on the peak response of selected neutral lipid classes were studied to optimize and calibrate the Iatroscan Mk-6s Chromarod system for qualitative and quantitative analysis of lipid classes by thin-layer chromatography (TLC) with flame ionization detection in fish oil during the transesterification process.
Abstract: Combined effects of hydrogen and air flow rates on the peak response of selected neutral lipid classes (triacylglycerol, diacylglycerol, monoacylglycerol, free fatty acids, and ethyl esters) were studied to optimize and calibrate the Iatroscan Mk-6s Chromarod system for the qualitative and quantitative analysis of lipid classes by thin-layer chromatography (TLC) with flame ionization detection in fish oil during the transesterification process. Air flow rate of 2 L/min, hydrogen flow rate of 150-160 mL/min, and scan rate of 30 s/rod were found to be the optimum conditions. All samples were also analyzed by high performance liquid chromatography (HPLC) with evaporative light scattering detection. Quantitative results obtained by TLC with the flame ionization detection method were comparable to those obtained from HPLC with evaporative light scattering detection.
TL;DR: The common adulterants are diazepam, phenobarbitone, saccharin, and chloral hydrate, used to make people addicted to toddy.
Abstract: Toddy is the fermented juice from a coconut, brab, date, or any kind of palm tree containing not more than 5% alcohol by volume [1]. It is regarded as a poor man’s drink and is consumed by many people in southern India. According to the Prevention of Food Adulteration Act [2] and the Bombay Prohibition Act [3] toddy should be free from harmful ingredients injurious to health. Despite this, adulterated toddy is very often reported by food and drug authorities, law enforcement agencies, and the state excise department. The common adulterants are diazepam, phenobarbitone, saccharin, and chloral hydrate, used to make people addicted to toddy. Such toddy samples are very often submitted to the State Public Health and Forensic Science Laboratories for measurement of their alcohol content and detection of illicitly added adulterants.
TL;DR: The presence of polycyclic or polynuclear aromatic hydrocarbons (PAHs) were investigated in sugar-beet from a local sugar factory in the district of Vojvodina as discussed by the authors.
Abstract: The presence of polycyclic or polynuclear aromatic hydrocarbons (PAHs) were investigated in sugar-beet from a local sugar factory in the district of Vojvodina. The sugar-beet was cultivated on areas near roads with intensive traffic. The procedure for the preparation and determination of these compounds included saponification of the sample, several liquid-liquid extraction systems and a silica gel column clean-up. The purified sam- ple solution was analysed by thin layer chromatography (TLC) on silica gel with cyclohex- ane as the developing solvent. Benzo(b)fluoranthene and benzo(a)anthracene and/or ben- zo(a)pyrene were detected at concentrations greater than the allowed limits in food.
TL;DR: The properties of the stationary phase can be optimized by adding FCDE-I to Si-60GF254, and this study may be useful in understanding both the systematic effects of stationary phase properties and those of the mobile phase on Rf values and the separability of components.
Abstract: Modified natural diatomaceous earth (DE) is a principal component of the stationary phase in normal thin-layer chromatography (TLC) applications and is mixed with commercial silica gel 60GF 254 (si-60GF 254 ). Modification is carried out by flux calcination and refluxing with acid. Natural DE, modified DEs [flux calcinated (FC)DE and FCDE-I), and Si-60GF 254 are characterized by scanning electron microscopy and Fourier-transform-IR spectroscopy. Particle size, specific surface area, pore distribution, pore volume, and surface hydroxyl group density parameters of materials are determined by various techniques. FCDE-I and Si-60GF 254 are investigated for their usefulness in the stationary phase of TLC both individually and in composition. Commercially available red and blue ink samples are run on layers of Si-60GF 254 and FCDE-I individually, and on various FCDE-I and Si-60GF 254 mixtures. Butanol-ethanol-2M ammonia (3:1:1, v/v) and butanol-acetic acid-water (12:3:5, v/v) mixtures are used as mobile phases. The polarities of stationary phases decrease, and the retention factor (R f ) values of ink components increase when the FCDE-I content of the stationary phase increases. The properties of the stationary phase can be optimized by adding FCDE-I to Si-60GF 254 . This study may be useful in understanding both the systematic effects of stationary phase properties [e.g., specific surface area and surface hydroxyl group density, α OH(s) ] and those of the mobile phase (e.g., polarity and acidity) on R f values and the separability of components.
TL;DR: In this paper, a process of derivatization involving formation of phenyl thiocarbamyl derivatives was used to separate groups of amino acids, which can be applied to sulfur compounds because their properties induce this reaction.
Abstract: To separate groups of amino acids we have used a process of derivatization involving formation of phenyl thiocarbamyl derivatives. Phenyl isothiocyanate was used as derivatization reagent. This particular reagent was chosen because the proposed method of detection entailed use of the iodine-azide reaction, which can be applied to sulfur compounds because their properties induce this reaction. Because amino acids do not belong to this group, it was necessary to perform a suitable transformation. The derivatization process was performed directly on the plate or in a tube, depending on the stationary phase chosen. After normal-phase (NP) TLC development with appropriate mobile phases, the plate was sprayed with a freshly prepared mixture of sodium azide and starch solution and exposed to iodine vapor. In reversed-phase TLC the plates were developed with mobile phase containing sodium azide and starch solution and then exposed to iodine vapor without being dried. In both NP and RP-TLC the catalytic effect of ...
TL;DR: In this article, a mixture of new pesticides admitted for marketing in Poland has been separated by use of two-dimensional thin-layer chromatography (2D-TLC) and the largest differences are obtained by combination of a normal phase (NP) system and a reversed phase (RP) system on a dual-adsorbent layer containing a narrow zone of silica and adjacent to a wide zone of octadecyl silica (or vice versa).
Abstract: A mixture of new pesticides admitted for marketing in Poland has been separated by use of two‐dimensional thin‐layer chromatography (2D‐TLC). The largest differences are obtained by combination of a normal‐phase (NP) system and a reversed‐phase (RP) system on a dual‐adsorbent layer containing a narrow zone of silica and adjacent to a wide zone of octadecyl silica (or vice versa). The greatest spread of points was obtained for the combination of nonaqueous NP phases with ethyl acetate–diisopropyl ether (2.5:97.5, v/v) on silica and RP phases, comprising a polar solvent (methanol or acetonitrile) in water on octadecyl silica adsorbent, which is wettable with water (RP‐18W). The correlations of R F values in NP/RP systems were utilized in the practical separation of a mixture of pesticides using 2D‐TLC on Multi‐K SC5 plate. The plates were scanned and videoscanned, showing the real pictures of TLC chromatograms.
Journal Article•
TL;DR: In this paper, the authors provide the latest information on new stationary phases for modern TLC and high performance TLC (HPTLC) and also provide practical and helpful hints on how to get the most out of this flexible form of chromatography.
Abstract: Thin-layer chromatography (TLC) is a planar chromatographic technique that is used in many laboratories throughout the world. Here, the authors provide the latest information on new stationary phases for modern TLC and high performance TLC (HPTLC). They also provide practical and helpful hints on how to get the most out of this flexible form of chromatography. Examples of separations showing the versatility of TLC and HPTLC are provided.
TL;DR: In this paper, the authors studied the oxidation behavior of 4H-1,4-benzothiazines and phenothiazine by 30% hydrogen peroxide in acetic acid.
Abstract: The study of the oxidation behavior of 4H-1,4-benzothiazines and phenothiazines by 30% hydrogen peroxide in acetic acid results in the formation of 4H-1,4-benzothiazine-1,1-dioxides (sulfones) and 10H-phenothiazine-5,5-dioxides (sulfones) respectively. The purity of all the synthesized compounds has been checked by thin layer chromatography using silica “G” as an adsorbent in various nonaqueous solvent systems. Infra-red and proton-magnetic resonance spectral studies are also included.
TL;DR: In this article, the salting-out performance of 15 mixed aminocarboxylato Co(III) complexes using eight ammonium sulphate solutions as mobile phases was investigated.
Abstract: Silica gel impregnated with poly(ethylene glycol) of different molecular mass (400, 1000, 1540, 4000, and 5500) was investigated for salting-out thin-layer chromatography of 15 mixed aminocarboxylato Co(III) complexes using eight ammonium sulphate solutions as mobile phases. Regularities established earlier for non-impregnated adsorbents are also valid in this work. Poly(ethylene glycol) of high molecular mass increases the hydrophobicity of the adsorbent. Positive linear dependence of RM values and of salting-out efficiency on average poly(ethylene glycol) molecular mass was usually observed. In contrast with non-impregnated silica gel, separation was achieved between complexes with the smallest hydrocarbon groups.
TL;DR: In this article, the authors examined the properties of bile acids: cholic acid, glycocholic acid (GC), glycolithocholic acid(GLC), deoxycholic acyclic acid (DC), glycodeoxy cholic acids (GDC), and lithocholic amino acid (LC) using thin layer chromatography at 18°C.
Abstract: The aim of our study was to examine the following bile acids: cholic acid (C), glycocholic acid (GC), glycolithocholic acid (GLC), deoxycholic acid (DC), chenodeoxycholic acid (CDC), glycodeoxycholic acid (GDC), and lithocholic acid (LC). In the present study, to separate a/m bile acids using adsorption thin layer chromatography at 18°C, the glass plates precoated with silica gel 60F254 (#1.05715), were impregnated with 1%, 2.5%, and 5% aqueous solutions of the following salts: CuSO4, MnSO4, NiSO4, and FeSO4. The mixtures of n‐hexane–ethyl acetate–acetic acid in the volume compositions: 22:20:5; 25:20:2; 25:20:5, and 25:20:8 were used as mobile phases. These mobile phases were not effective for the separation of bile acids on non impregnated silica gel 60F254 plates at 18°C. The plates impregnated with the salts whose application resulted in ΔRF≥0.05 and RS>1 for all neighboring pairs of examined bile acids were considered the most effective for bile acids separation. It was observed that impregn...
Journal Article•
TL;DR: HPLC is the most reliable and applicable method in this regard for determining the amount of sildenafil in pharmaceutical preparations, soft drinks, and biological liquids.
Abstract: Determination of sildenafil by various methods and in various media is reviewed in this paper. The methods used consist of ultraviolet (UV) spectroscopy, thin layer chromatography (TLC), and highperformance liquid chromatography (HPLC). These methods were used to determine the amount of sildenafil in pharmaceutical preparations, soft drinks, and biological liquids. HPLC was used for evaluation of pharmacokinetic parameters of sildenafil. It is concluded that HPLC is the most reliable and applicable method in this regard.