Quantitative Auswertung von Dünnschicht-Chromatogrammen: On line-Kopplung mit programmierbaren elektronischen Tischrechnern

A TLC method for the determination of phenacetin and caffeine in pharmaceutical preparations using a densitometer in line with an integrator and electronic desk calculator is described. The calibration curves of each compound were prepared where the higher and lower tolerance concentration levels were defined. The accuracy of the method is 1.51% (phenacetin) and 2.56% (caffeine) for two experiments carried out on each plate; 1.50% (phenacetin) and 2.64% (caffeine) for four experiments for each plate (relative standard deviation, n=18 and n=36, respectively).     

Simultaneous Determination of Caffeine and Antipyrine in Plasma and Saliva using High-Performance Liquid Chromatography

Abstract

A rapid and sensitive method of quantitation of caffeine and antipyrine in plasma and saliva is described. Caffeine, antipyrine and phenacetin, the internal standard, are readily extracted from alkalinized plasma and saliva into dichloromethane. After evaporation of the organic solvent, the residue is analyzed by HPLC using a mobile phase of 25% acetonitrile in 0.02 M phosphate buffer at a flow rate of 1.5 ml/min. and a C18 reverse phase column. Baseline separation of all peaks is achieved with retention times for all compounds of less than 10 minutes. There is no interference from endogenous compounds or metabolites of caffeine or antipyrine.     

Simultaneous High-Performance Liquid Chromatographic Assay of Acetaminophen,Acetylsalicylic Acid,Caffeine, and D-Propoxyphene Hydrochloride

Abstract

A reversed phase high-performance liquid chromatography (HPLC) method for simultaneous measurement of acetaminophen (I), acetylsalicylic acid (II), caffeine (III) and d-propoxyphene (IV), using phenacetin (V) as an internal standard was developed. Using a 6.5 μ C-8 reversed phase column (RPP) with a mobile phase consisting of 0.01M sodium acetate solution: methanol (85:15%) at pH 4.1 enabled the Chromatographic separation of the four components in about 12 min. Quantitation was achieved by measuring the peak height ratio of each component relative to the internal standard. the validity of the developed method was tested by analyzing laboratory-prepared mixtures containing the four components in various proportions. Assay precision and sensitivity have been established for each component. the developed method proved to be stability-indicating as it can be applied to monitor salicylic acid as a degradation product in acetylsalicylic acid samples.     

三重-比导数分光光度法同时测定氨基比林、非那西丁和咖啡因含量的研究

阐述了三重-比导数分光光度法同时测定氨基比林、非那西丁和咖啡因的基本原理,并研究了实验条件。试验结果表明,氨基比林的平均回收率为103.3%,相对标准偏差(RSD)为2.3%(n=13);非那西丁的平均回收率为99.44%,RSD为1.2%(n=13);咖啡因的平均回收率为98.41%,RSD为1.1%(n=13)。     

微乳液毛细管电动色谱快速分析解热镇痛药中的有效成分

建立了微乳液毛细管电动色谱快速测定解热镇痛药中非那西丁、氨基比林和咖啡因的新方法。采用由乙酸乙酯-十二烷基硫酸钠(SDS)-正丁醇-硼砂缓冲液组成的微乳液体系,以氯霉素为内标,3种有效成分在2.5 min内完成分离,峰面积相对标准偏差(RSD)在1.2%～1.6%之间,回收率在95.6%～104.0%之间。实验考察了缓冲溶液的浓度、pH值、SDS浓度以及助表面活性剂的种类、含量对分离测定的影响。该法可用于实际样品分析。     

Modeling of chromatographic retention of the selected antiarrhythmics and structurally related compounds in the hydrophilic interactions under the TLC and HPLC conditions

Abstract

High-performance liquid chromatography (HPLC) plays an important role in testing the pharmaceutically active compounds. In despite of the advantages of HPLC, thin-layer chromatography (TLC) retains its applicability to the different experimental tasks. The experimental conditions which allow hydrophilic interactions in the chromatographic system were tested in the HPLC and TLC systems for ivabradine, its related compounds, diltiazem and verapamil. Under the TLC conditions, retention behavior of the investigated compounds was tested on silica gel modified with cyanopropyl ligands as stationary phase and acetonitrile?+?methanol containing 25% v/v formic acid. Under the HPLC conditions, we used silica gel modified with cyanopropyl ligands as a column packing and the acetonitrile + 0.25% aqueous solution of formic acid as mobile phase. Retention behavior of the investigated analytes depending on the changing volume fractions of the mobile phase modifier was characterized both for TLC and HPLC data sets by the Soczewiński–Wachtmeister equation. Linear relationships were established between the retention coefficients characterizing the retention mechanism (R_M⁰/m, logk₀/m) and molecular properties of the investigated compounds. The Quantitative Structure Retention Relationship (QSRR) modeling was performed with the use of the stepwise multiple linear regression, in order to select molecular properties which influence retention.     

Separations in Thin Layer and High Performance Liquid Chromatography Using Alkyl Silica Gel Bonded Phases

Abstract

Separations in thin layer (TLC) and high performance liquid chromatography (HPLC) using alkyl bonded phases were carried out under optimum solvent conditions for each of three phases, RP-2, RP-8 and RP-18. The phases were tested for their efficiency and resolving power using three groups of compounds in three binary organic-water mobile phases. The organic solvents were acetonitrile, methanol and tetrahydrofuran, which are widely used as solvent modifiers in reversed phase liquid chromatography.

The results showed that, unlike HPLC, TLC using RP-18 plates was the most, and RP-2 plates the least, efficient. A naphthalene and biphenyl mixture which was resolved by HPLC using any of the three solvents and columns was not resolved by TLC using any plate or solvent combination, unless the plate was prewashed with an organic modifier. The addition of NaCl (1–2% wt/vol) to the solvent for TLC speeded development unless an alcohol was used, but did not greatly affect the separation.     

Molecular Ionization-Desorption Analysis Source (MIDAS) for Mass Spectrometry: Thin-Layer Chromatography

Molecular ionization-desorption analysis source (MIDAS), which is a desorption atmospheric pressure chemical ionization (DAPCI) type source, for mass spectrometry has been developed as a multi-functional platform for the direct sampling of surfaces. In this article, its utility for the analysis of thin-layer chromatography (TLC) plates is highlighted. Amino acids, which are difficult to visualize without staining reagents or charring, were detected and identified directly from a TLC plate. To demonstrate the full potential of MIDAS, all active ingredients from an analgesic tablet, separated on a TLC plate, were successfully detected using both positive and negative ion modes. The identity of each of the compounds was confirmed from their mass spectra and compared against standards. Post separation, the chemical signal (blue permanent marker) as reference marks placed at the origin and solvent front were used to calculate retention factor (R_f) values from the resulting ion chromatogram. The quantitative capabilities of the device were exhibited by scanning caffeine spots on a TLC plate of increasing sample amount. A linear curve based on peak are, R² = 0.994, was generated for seven spots ranging from 50 to 1000 ng of caffeine per spot.

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Simultaneous Determination of Acetaminophen, Caffeine, and Chlorphenamine Maleate in Paracetamol and Chlorphenamine Maleate Granules

A simple and rapid HPLC method using phenacetin (PHN) as internal standard has been developed for simultaneous determination of acetaminophen, caffeine, and chlorphenamine maleate in the product compound paracetamol and chlorphenamine maleate granules. Separation and quantitation were achieved on a 250 mm × 4.6 mm, 5 μm particle, C₁₈ column. The mobile phase was methanol 0.05 mol L^?1 aqueous KH₂PO₄ solution, 45:55 (v/v), containing 0.1% triethylamine and adjusted to pH 3.6 by addition of phosphoric acid; the flow rate was 1.0 mL min^?1. Detection of all compounds was by UV absorbance at 260 nm and elution of the analytes was achieved in less than 12 min. The linearity, accuracy, and precision of the method were acceptable to good over the concentration ranges 6.4–153.6 μg mL^?1 for acetaminophen, 5.0–120.0 μg mL^?1 for caffeine, and 9.6–230.4 μg mL^?1 for chlorphenamine maleate.     

Determination of Aminacrine Hydro-Chloride in Drug Preparations by TLC with Fluorescence Densitometry

Abstract

A densitometric TLC method was developed for quantification of aminacrine hydrochloride in creams, jellies, and suppositories. Aminacrine was extracted into acidic ethanol, diluted to a known volume, and separated by high performance silica gel TLC. The fluorescence of aminacrine zones in samples and standards was compared by in situ scanning. Recoveries of aminacrine from authentic samples ranged from 95.4 to 103.4%.     

Determination of Pentachlorophenol Residues in Tallow by Quantitative TLC

Abstract

A TLC method is described for screening and quantification of PCP in tallow. PCP is extracted and cleaned up by alumina column chromatography, and is determined by preadsorbent silica gel TLC with silver nitrate detection and densitometric scanning. The detection limit of the analysis was 0.50 ppm in tallow. Recoveries varied from 97.9 to 103% over the fortification range of 1 to 20 ppm. The CV of the analysis was 6.2% .     

Determination of Triazine and Chlorophenoxy Acid Herbicides in Natural Water Samples By Solid Phase Extraction and Quantitative Thin Layer Chromatography

Abstract

Atrazine, simazine, 2, 4-D, silvex, and 2, 4, 5-T, were determined in natural water samples at 10 ppb levels by solid phase extraction on disposable C₁₈ columns and TLC on preadsorbent silica gel layers impregnated with AgNO₃, exposure to UV light, and densitometric scanning. Recoveries ranged from 70 to 88% for the triazines and 93 to 100% for chlorphenoxy acid herbicides, with average CV values of 7 to 8%. Solid phase extraction proved to be an advantageous alternative to classical liquid-liquid partition for the analysis of water for these compounds by quantitative TLC.     

多波长线性回归紫外分光光度法同时测定复方阿斯匹林片中的三组分

用改进的多波长线性回归分光光度法同时测定了复方阿期匹林片中三组分的含量,模拟样品中阿斯匹林、非那西丁、咖啡因的平均回收率分别为１００．３１％、９９．８７％、１００．７７％,相对标准偏差分别为０．３５％、０．２５％、１．３７％（ｎ＝１０）。对四个批号实际样品的测定结果与标准方法一致,适物复方阿斯匹林片的常规分析。     

Quantitative Analysis of a Chloroquinolin-Ethenyl Phenyl Derivative Using Thin Layers Impregnated With Di-P-Toluyl Tartaricacid

Abstract

Thin Layer Chromatography (TLC) is an established method for the evaluation of final product drug and intermediate impurity profiles. Quantitative TLC has gained credibility within the Pharmaceutical industry as a result of the latest developments in an availability of scanning technology. In the present paper we wish to report a quantitative TLC method for the determination of some potential impurities which may exist in a final bulk drug MK0679. In order to improve the selectivity of the chromatographic method, di-p-toluyl tartaric acid was impregnated on the stationary phase. Utilizing the modified layer, complete separation of the known impurity was obtained. The calibration curves for all components studied were linear and the detection limits obtained were less than 5ng.     

Application of Thin-Layer Chromatography to High-Performance Liquid Chromatographic Separation of Steroidal Hormones and Cephalosporin Antibiotics

Abstract

High-performance liquid chromatographic (HPLC) separation of steroidal hormones and cephalosporin antibiotics was investigated by adsorption chromatography and reversed-phase chromatography, respectively.

Prior to the HPLC separation of these pharmaceuticals, silica gel thin-layer adsorption chromatography of steroidal hormones and reversed-phase thin-layer partition chromatography of cephalosporin antibiotics with chemically bonded dimethylsilyl silica gel were performed in order to obtain suitable HPLC separation systems.

In the separation of steroidal hormones, the same binary mobile phase ratios of TLC did not give satisfactory results in HPLC. For the sharp separation in HPLC, solvent strength in the binary solvent mixture used for TLC had to be decreased.

The difference in solvent strength for efficient separation between TLC and HPLC might be attributed to the fact that in HPLC the solvent elution power acts in an isocratic manner while in TLC it acts in a gradient manner.

On the other hand, a correlation of mobility between TLC and HPLC separation for cephalosporin antibiotics was obtained, and the possibility of direct transfer of chromatographic systems from TLC to HPLC for separation of these antibiotics was confirmed.     

Extraction Rapide de la Cafeine Urinaire Sur Cartouche C18 Et Dosage Par Chromatographie Gazeuse

Abstract

A rapid method for urinary caffeine extraction on C₁₈ cartridge before GC determination is proposed in view of doping controls in sport. The choice of the standard and of the analytical procedure has been directed by the necessity of rapid determination.

Caffeine extraction on C₁₈ reverse-phase is achieved with a good efficiency (recovery : 98 %, CV = 3 %), so that use of an internal standard was not found necessary. Amobarbital was chosen as internal standard in GC because of several advantages : retention time, thermal stability, interesting properties in mass fragmentometry.     

Simultaneous Determination of Caffeine and Meclizine Dihydrochloride in Sugar-Coated Tablets

Abstract

In this study, simultaneous determination of caffeine and meclizine dihydrochloride in their binary mixture was conducted by two spectrophotometric methods. In the first method, derivative spectrophotometry, the quantification of caffeine and meclizine dihydrochloride was performed by reading the dA/dλ values at 286.2 nm and 243.4 nm respectively in the first derivative spectra of their mixture in methanol. The relative standard deviation of the method was 0.54% for caffeine and 0.67% for meclizine dihydrochloride. In the second, selective precipitation + derivative spectrophotometry, determination of meclizine dihydrochloride was carried out by precipitation with potassium ferricyanide at pH 2 selectively, then measuring the absorbance of its solution in methanol at 420.8 nm, and determination of caffeine was succeeded by reading the dA/dλ values at 260.6 nm in the first derivative spectra of the remaining solution after precipitation. Relative standard deviation of the method was found to be 0.56% for caffeine and 1.85% for meclizine dihydrochloride. These two methods were applied successfully to a sugar-coated tablet containing these drugs.     

Determination of Allantoin in Drug Preparations by Quantitative High Performance TLC

Abstract

A densitometric TLC method was developed for the quantification of allantoin in creams and suppositories used to treat vaginal infections. Allantoin was extracted with water at elevated temperature, diluted to a known volume, and separated by HP silica gel TLC. Allantoin was detected by spraying with p-dimethylamine-benzaldehyde reagent. The absorption of standards and samples was compared by in situ scanning. Recoveries of allantoin from authentic samples ranged from 96–102%, except for one sample that assayed high. The accuracy of the method was demonstrated by standard addition analysis of this sample.     

An efficient and simultaneous analysis of caffeine and paracetamol in pharmaceutical formulations using TLC with a fluorescence plate reader

A simple, rapid, and efficient method using TLC with a fluorescence plate reader has been described for simultaneous determination of caffeine and paracetamol. Determination was carried out using the fluorescence-quenching action of caffeine and paracetamol on a TLC plate with a fluorescent indicator at lambda ex = 254 nm in the linear ranges of 0.2-1.9 and 0.03-1.5 microg/L, respectively. Separation of caffeine and paracetamol were performed on the TLC plate, and the best results were obtained using the optimized mobile phase n-hexane-ethyl acetate-ethanol (2.5 + 1.5 + 0.4, v/v). Some important parameters, such as solvent type and ratio of the mobile phase, the presence of other components, and instrumental parameters, were studied. Caffeine and paracetamol detection limits were 0.025 and 0.032 microg/L, and RSD values for 0.6 microg/L caffeine and 0.06 microg/L paracetamol (n = 5) were 1.93 and 2.06%, respectively. Using this technique, some pharmaceuticals containing caffeine and paracetamol were analyzed with satisfactory results.     

Determination of Biphenyl in Citrus Fruits by Quantitative Thin-Layer Chromatography

Abstract

Residues of the fungicide biphenyl in citrus fruits have been determined by direct scanning of spots on phosphor-impregnated high performance silica gel TLC plates under UV light. Biphenyl was separated from fruit tissue by steam liquid-liquid extraction. Recoveries from spiked samples ranged from 92–99% at 100, 50, and 10 ppm levels. The precision of the TLC determination and overall procedure are shown to be adequate for residue analysis.