Simultaneous determination of a mixture of organophosphorus and carbamate pesticides by high performance liquid chromatography.

A simple HPLC procedure has been developed for the simultaneous determination of a mixture of standard carbaryl, carbofuran, carbendazim, dimethoate, malathion and methyl parathion from a spiked agricultural soil sample. The pesticide mixture has been extracted using methanol-water. A concave gradient elution with acetonitrile-phosphate buffer for 15 min followed by linear elution for 5 min, using a wavelength of 224 nm for detection, has been found to resolve the mixture efficiently.

Improved thin layer chromatographic resolution of PTH amino acids with some new solvent systems.

Three new solvent systems, pyridine: benzene (2.5:20, v/v), methanol:carbon tetrachloride (1:20, v/v) and acetone:dichloromethane (0.3:8, v/v), for the resolution of a mixture of 18 PTH amino acids have been reported.

Resolution of enantiomers of amino acids by HPLC.

Application of HPLC as a prime tool in the area of enantiomeric resolution has opened doors of success and varied interest. Use of chiral reagents either indirectly (as derivatization reagent) or directly (added to stationary or mobile phase) has led to achieve resolution of a wide range of compounds. Amino acids, being important molecules with simple structure and easy availability, have been extensively studied.

Family types and communication with parents: A comparison of youth at different identity levels.

Recent theory views adolescent behavior as nested in an ongoing system of family relationships. In keeping with this focus, differences in family functioning of high vs. low identity achievement youth were examined and variables to account for differing identity levels were explored.

TLC separation of certain tetracycline and amino glycopeptide antibiotics.

The separation of tetracycline and amino glycopeptide antibiotics was achieved on silica gel thin layers. Tetracycline antibiotics were resolved on a Co+2 (1.0%) impregnated silica gel layer using ethanol:acetic acid:water (10:6:6, v/v/v) as the mobile phase.

Pituitary response to growth hormone-releasing hormone in IDDM. Abnormal responses to insulin and hyperglycemia.

In poorly controlled insulin-dependent diabetes mellitus (IDDM), hyperglycemia fails to inhibit the pituitary response to growth hormone-releasing factor (GRF). To evaluate whether this derangement is reversed by a simultaneous elevation of circulating insulin, 0.3 micrograms/kg i.

Complete amino acid sequence of a subunit from rapeseed high molecular weight protein.

A subunit (Mr 15,600) from the high molecular weight protein from rapeseed was separated and isolated; its purity and homogeneity were ascertained. The subunit was cleaved with cyanogen bromide, trypsin, chymotrypsin, and Staphylococcus aureus V8 protease. The fragments were separated and isolated by polyacrylamide gel electrophoresis, gel filtration, column chromatography on Dowex 1 x 2, and paper electrophoresis.

Complete amino acid sequence of arachin subunit of molecular weight 21,000.

A subunit of molecular weight 21,000 from arachin, the major peanut protein, was isolated in pure form and primary structure was determined. The subunit was fragmented with CNBr, trypsin, and NBS; the fragments were separated and isolated by PAGE, gel filtration, Dowex treatment, and paper electrophoresis, and Edman degradation on each fragment, including the intact subunit, was performed. The PTH-amino acids thus obtained were identified by UV spectroscopy and TLC.

Reconstitution of rapeseed high molecular weight protein from isolated subunits.

The high molecular weight protein was isolated from rapeseed and characterised. Six subunits were isolated in SDS (0.01%) solution on polyacrylamide-gel electrophoresis and by gel filtration on Sephadex G-100.

Importance of enantiomeric purity and its control by thin-layer chromatography.

Methods for the direct resolution of enantiomers are important and are necessary for pharmaceutical and biomedical analysis, synthetic and mechanistic studies and various other fields. The present paper deals with the results of recent approaches, such as ligand exchange, ion exchange and steric interactions, providing direct resolution of enantiomers of a variety of compounds by thin-layer chromatography. General aspects of various methods for analysis of enantiomeric purity and resolution have been compared.

T.l.c. enantiomeric separation of amino acids.

Resolution of enantiomers is very important particularly in the fields of asymmetric synthesis, mechanistic studies, geochronology, studies of structure-function relationship of proteins, pharmacology, and medicine. Various chromatographic methods have replaced the classical fractional crystallization, seeding and enzymatic procedures. Of these, t.

Thin layer chromatography of dansyl and dinitrophenyl derivatives of amino acids. A review.

The dinitrophenyl (DNP) derivatives of amino acids have found continual application in protein sequencing since Sanger used them for the first time for the sequencing of insulin. Dansyl derivatives of amino acids have been widely used in protein sequencing because of their fluorescent nature. The success of protein sequencing largely depends upon correct identification of such derivatives.

Hydrogen ion titration of 12 S rape seed protein and partial N-terminal sequence of one of it's subunits.

The high molecular weight 12 S protein from rape seed was isolated in a homogeneous form and characterized. Six subunits were isolated by PAGE in the presence of SDS and 0.2 M 2-mercaptoethanol.

Separation of some antihistamines on impregnated TLC silica plates.

Different metal salts have been tried as impregnating reagents for developing TLC separation schemes for some antihistamines on silica gel 'G' plates, using a new solvent system benzene + dimethyl formamide + acetic acid (30:10:7). Spots were visualized by spraying with a solution of Dragendroff's reagent.

Improved TLC systems for rapid resolution of phenyl thiohydantoin amino acids.

Two new solvent systems, n-hexane + propionic acid (26:5, v/v) and chloroform + acetone (29:3, v/v), for the rapid resolution and identification of an 18-component mixture of phenylthiohydantoin amino acids are reported. Using these systems certain difficult combinations of phenylthiohydantoin amino acids are resolved. Two more solvent systems, viz chloroform + acetic acid (27:3, v/v) and chloroform + methanol (30:4, v/v), are developed to resolve phenylthiodantoin derivatives of aspartic and glutamic acids.

Rapid resolution of phenylthiohydantoin amino acids by thin-layer chromatography on silica gel plates impregnated with transition metal ions.

The resolution of a 15-component mixture of phenylthiohydantoin (PTH) amino acids using metal ion impregnated silica gel plates is reported. The spots are located by exposing the chromatograms to an iodine chamber. The method provides a rapid, simple, and less expensive chromatographic system, provides resolution for certain difficult combinations, and leaves the PTH amino acids unaltered chemically.

[Prevalence of antibodies against HTLV-III in various regions in Switzerland].

Acquired immune deficiency syndrome (AIDS) has been etiologically linked with the human T-cell lymphotropic virus HTLV-III. In a study on the prevalence of antibodies to this virus in Switzerland, sera from 941 individuals were collected in 5 major urban areas (Basel, Berne, Geneva, Lausanne and Zurich) in 1983 and 1984. All sera were tested by ELISA and the majority also by Western blot.

Metabolism of Monoterpenes : Early Steps in the Metabolism of d-Neomenthyl-beta-d-Glucoside in Peppermint (Mentha piperita) Rhizomes.

Previous studies have shown that the monoterpene ketone l-[G-(3)H] menthone is reduced to the epimeric alcohols l-menthol and d-neomenthol in leaves of flowering peppermint (Mentha piperita L.), and that a portion of the menthol is converted to menthyl acetate while the bulk of the neomenthol is transformed to neomenthyl-beta-d-glucoside which is then transported to the rhizome (Croteau, Martinkus 1979 Plant Physiol 64: 169-175). Analysis of the disposition of l-[G-(3)H]menthone applied to midstem leaves of intact flowering plants allowed the kinetics of synthesis and transport of the monoterpenyl glucoside to be determined, and gave strong indication that the glucoside was subsequently metabolized in the rhizome.

Structure of cadabalone.

From the pods of Cadaba fructicosa L., a new dilactone designated as cadabalone, has been isolated. Based on reactions and spectral data, structure I has been assigned for cadabalone.

Metabolism and probable active metabolite of alpha-l-acetylmethadol in rat.

alpha-l-Acetylmethadol is being currently evaluated as a substitute for methadone in the treatment of heroin addicts. The metabolites, isolated from urine, liver, and serum, were identified by gas-liquid chromatography. Methadone and its metabolites were found to be present in urine, liver and serum of rats treated with alpha-l-acetylmethadol.

Thin-layer and gas chromatographic determination of ketamine and its biotransformed products in biological fluids.

Ketamine, (2-(o-chlorophenyl)-2-methylamine cyclohexanone) and its in vivo metabolite I (2-(o-chlorophenyl)-2-aminocyclohexanone) and metabolite II (2-(o-chlorophenyl)-2-amino-5-cyclohexene-1-one) were determined by thin-layer (TLC) and gas chromatography (GC). In vivo studies include intraperitoneal injection of ketamine in rats. Urine and blood samples were collected at regular intervals.