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%.     

Synthetic Inorganic Ion Exchangers. XIV Thin-Layer Chromatography of Metal Ions on Thorium Phosphate: Quantitative Separation of Au (III) from Several Metal Ions

Abstract

The analytical potential of thorium phosphate as an ion exchanger has been explored by thin layer chromatographic (TLC) technique. Binder-free thin layers of thorium phos -phate have been explored for several important binary and ternary separations. A TLC method has been developed for quantitative separation of microgram-quantities of Au(III) from several metal ions in pure butanol system.     

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.     

Mechanistic Study of Microwave-Assisted Acid Hydrolysis of Peptides on TLC Plates

Abstract

Microwave-induced acid hydrolysis was performed with isolated peptides on TLC layers. This vapor phase method was compared to solution phase techniques. A mechanistic study of peptide bond clevage was carried out by varying exposure conditions and reaction time. Acid hydrolysis products were identified by ninhydrin visualization. Also, TLC and TLC/MS were used to elucidate hydrolysis mechanisms.     

Liquid Chromatography Analysis of Hippuric Acid

Abstract

Hippuric acid analysis by TLC is demonstrated. Both normal silica and reverse phase C¹⁸ TLC plates are used with fluorescent quenching to visualize the hippuric acid. Urine samples may be spotted directly or extracted with CHCl₃ to concentrate the hippurate. Tissues may be analyzed in this same manner. Aluminum backed Merck TLC plates give best normal phase separation of tissue extracts and Whatman C¹⁸ give best reverse phase separation of tissue extracts. A Kontes scanner may be used to directly analyze TLC plates or the bands may be removed and analyzed by ultraviolet spectroscopy. Confirmation may be done by mass spectrometry.     

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 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.     

Chromatography of Trichothecene Mycotoxins

Abstract

Trichothecene mycotoxins occur in agricultural commodities and can cause problems from feed refusal to death in animals. This paper describes chromatographic methods for selective analysis for trichothecene mycotoxins. These methods include gas chromatography (GC), thin layer chromatography (TLC), and high pressure liquid chromatography (HPLC). The trichothecene analysis methods by GC and TLC are shown to have a greater sensitivity than in HPLC for the underivatized mycotoxins.     

Analysis of Analgesic Tablets by Quantitative High-Performance Reversed Phase TLC

Abstract

Aspirin, phenacetin, and caffeine in two commercial analgesic tablets were determined by scanning of fluorescence-quenched zones after separation on high performance TLC plates. Assays for the components ranged from 100 to 88% of label values, and agreement between duplicate samples was better than 5%. Use of phenacetin as an internal standard for determination of aspirin and caffeine was not advantageous. The analysis serves well as an introduction to quantitative TLC in undergraduate laboratory courses.     

Imaging and Quantitation of One and Two Dimensional TLC With a New Radioanalytic Imaging System

Abstract

A new method for the imaging and quantitation of radiolabeled substrates fractionated on one or two dimensional (2D) TLC plates has been developed. The TLC sample is read by a microcomputer-controlled beta- and gamma-sensitive gas proportional counter. The TLC plate is scanned by a 20 × 20 cm array of 952 individual detector elements, and the resulting quantitative image is displayed on a high resolution monitor for analysis. Individual radioactive spots may be quantitated on-screen.     

Determination of Lead and Cadmium by Stripping Voltammetry After Separation from Humic Acid by Thin-Layer Chromatography

Abstract

Interferences resulting from the presence of humic acid (HA) and other surface-active substances in a sample matrix decrease the reliability of Pb and Cd determinations obtained by square-wave anodic stripping voltammetry (SWASV). The implementation of thin-layer chromatography (TLC) prior to SWASV minimizes the effect of these interferents by physically separating Pb and Cd from the sample matrix prior to analysis. The determination of both Pb and Cd was shown to be feasible after TLC separation from laboratory standards spiked with 100 ppm humic acid and from a lake water sample spiked with 1 ppm of Pb and Cd.     

Analysis of PCB's by Thin-Layer Chromatography

Abstract

A screening thin layer chromatography (TLC) technique has been developed that can be done in the field. Quantitative analysis by TLC densitometry can be done in a laboratory (or field van). A densitometer is needed for quantitative work by TLC. An Apple computer may be added to use as a computational device. Semi-quantitative results may be obtained by visual comparisons. Confirmations may be made by silver halide visualization on TLC. Dehalogenation with sodium biphenyl, chlorination with antimony pentachloride, or mass spectral confirmation may be used. Quantitative analysis is possible of the derivatized positive samples.     

The Importance of Effective Predevelopment Plate Washing Techniques in Thin-Layer Chromatography

Abstract

Comparative studies were made of the two methods commonly used for predevelopment TLC plate cleaning. In separate studies TLC plates were washed by the two methods: ascending development and dip washing using several solvent and solvent combinations. Residues remaining on the surface of plates after washing were visualized by fluorescence techniques and scanned by densitometry. Evaluation of the two washing methods showed that plate dipping gave superior results in every case over ascending development. The most effective solvent for predevelopment TLC plate washing was found to be methanol.     

Identification of Some Closely Related Potential Antidiabetic 4-Arylhydrazono-1-Guanylnitrate-3-Methyl-2-Pyrazolin-5-Ones

Abstract

As an extension of our studies on thin-layer chromatographic (TLC) analysis of antineoplastics¹ and antidiabetics², we investigated the TLC separation of some closely related potential antidiabetic 4-arylhydrazono-1-guanylnitrates-3-methyl-2-pyrazolin-5-ones(A).     

The Application of Cross-Scanning to Conventional Thin-Layer Chromatography

Abstract

The technique of cross-scanning, the scanning of thin-layer chromatographic (TLC) plates perpendicular to the direction of development, is applicable to conventional quantitative TLC where significant advantages over normal scanning are realized by its use. Several factors are discussed which influence the ability to cross-scan, such as application of the sample, solvent development and instrumentation.     

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.     

Thin Layer Chromatography-Laser Mass Spectrometry (TLC-LMS) of Triphenylmethane Dyes: Initial Results

Abstract

Laser mass spectra (LMS) of triphenylmethane dyes were obtained directly from a thin layer chromatographic (TLC) plate using the LAMMA-1000 laser microprobe. Spectra obtained from TLC plates were very similar to those obtained from standard substrates, the only difference being that at threshold power densities spectra from the TLC plates show greater fragmentation. The region below m/z 100 is mostly obscured by peaks due to the chromatographic support; above this range, peaks can be identified corresponding to the molecular cation and simple neutral losses. The inherent lateral rèsolution of the Instrument (～5 μm) was used to resolve multiple components in broad chromatographic spots. The TLC-LMS combination has the advantage that components can be identified even if they are not completely resolved chromatographically.     

Fluorogenic Labelling of Carbonylcompounds with 7-Hydrazine-4-nitrobenzo-2-oxa-1,3-diazole (NBD-H)

Abstract

A method for the prechromatographic fluorescence derivatization of carbonyl compounds with 7-hydrazino-4-nitrobenzo-2-oxa-1,3-diazole (NBD-H) is presented. The separation and quantitation of the hydrazones is carried out by TLC and HPLC on silica gel and RP-ma-terials. Detection limits obtained for benzaldehyde by TLC with fluorodensitometric evaluation are 5 ng/spot and by HPLC with fluorescence detection 200 pg.     

SYNTHESIS OF SOME NEW 3-BENZYL-2-ARYLIMINO-4-THIAZOLIDINONE-1,1-DIOXIDES

Abstract

Twenty new 3-benzyl-2-arylimino-4-thiazolidinone-1,1-dioxides (2) were synthesized by oxidising 3-benzyl-2-arylimino-4-thiazolidinones (1) with potassium permanganate in glacial acetic acid. The homogeneity and purity was confirmed by TLC and some of the dioxides were screened for their insecticidal, acaricidal and herbicidal activities.     

Impregnated silica-based layers in thin layer chromatography

Abstract

Impregnated thin-layer chromatography (TLC) layers based on silica gel are presented. Impregnating agents such as metal cations, inorganic ions, chelating agents, chiral selectors, surfactants, ion-pairing reagents, and ionic liquids are discussed. The role of impregnated TLC layers in medicinal chemistry is highlighted. The historical overview of TLC separations on physically coated layers is given and some future prospects ahead of this technique are discussed.