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Biomedical subjects

K E Rasmussen

Publications and source records attributed to K E Rasmussen.

At least 55 records · Page 3Linked to original sources
PubMed1985

Use of bonded-phase silica sorbents for rapid sampling of impurities in illicit amphetamine for high-performance liquid chromatographic analyses.

A simple and rapid method has been developed for the extraction of impurities from illicit amphetamine samples using bonded-phase silica sorbents. The drug is dissolved in phosphate buffer (pH 7) and added to a C8 Bond Elut extraction column. The column is washed with water, and the impurities are then eluted with acetonitrile. The eluate is directly injected into the liquid chromatograph. This sample preparation technique has been compared with the traditional liquid-liquid extraction method. High-performance liquid chromatographic analysis of the impurities is carried out on a reversed-phase C18 column with an acetonitrile-water gradient as mobile phase. Peaks are monitored by UV detection at 220 and 254 nm. A series of seized amphetamine samples has been analysed, and the procedure gives detailed impurity patterns suitable for the comparison of samples. Compounds are identified by absorbance ratios (A220/A254).

Amphetamine↗
PubMed1983

Screening of hallucinogenic mushrooms with high-performance liquid chromatography and multiple detection.

A rapid, sensitive and specific method for the screening of hallucinogenic mushrooms has been developed. High-performance liquid chromatography with simultaneous use of ultraviolet, fluorescence and electrochemical detection was employed. Separation of the mushroom components was achieved on a silica column using an alkaline aqueous methanolic eluent. The use of detector response ratios for identification of hallucinogenic indole alkaloids has been evaluated.

Basidiomycota↗
PubMed1980

Glass capillary column gas chromatography of barbiturates after flash-heater derivatization with dimethylformamide dimethylacetal.

Glass capillary column gas chromatography has been used for quantitative and qualitative analyses of barbiturates. The barbiturates are first converted into the corresponding acetal derivates by flash-heater derivatization, using dimethylformamide dimethylacetal as the derivatization reagent. The influence of the injection port temperature, the column temperature, the solvent used to dissolve the substances and the reagent dilution were studied in order to obtain the optimal response with good reproducibility. Calibration graphs in the concentration range 5--50 micrograms/ml were evaluated and the relative standard deviations for the quantitative analyses were calculated. High sensitivity was obtained when extracts from plasma containing phenobarbital in the low therapeutic concentration range were analysed using the described derivatization technique.

Barbiturates↗
PubMed1977

Determination of hydrochlorothiazide in serum by high-pressure liquid chromatography.

A quantitative high-pressure liquid chromatographic method has been developed for the analysis of hydrochlorothiazide in serum in therapeutical concentrations. The method is based on gel filtration of the sera on Sephadex G-15, extraction of the protein-free fraction of the effluent with ethyl acetate and injection of a methanol solution of the drug extract on a reversed-phase column packed with Spherisorb ODS (particle size, 10 mum). The mobile phase is 15% methanol in water. The detection limit is 50 ng/ml of serum. Serum samples from patients receiving hydrochlorothiazide have been analysed by the described method at different hours postdose.

Chromatography, Gel↗
PubMed1977

Aphakic glaucoma.

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Aphakia, Postcataract↗
PubMed1976

Diagnostic value of the water-drinking test in early detection of simple glaucoma.

A series of 64 patients (119 eyes) subjected 10 years previously to water provocative tests on a suspicion of simple glaucoma were followed up. At that time the intraocular tension exceeded 20 mmHg, but there were no optic disc changes and no visual field defects. The follow-up examination comprised ophthalmoscopy, visual acuity, gonioscopy, intraocular tension, and perimetry. Setting a rise of 8 mmHg as the lower limit, the water provocative test ten years previously had been positive in 31 eyes. Nine of these developed glaucomatous visual field defects despite treatment (29 per cent). The test had been negative in 88 eyes. Of these, 21 (24 per cent) developed glaucomatous visual field defects. The water-drinking test was negative in 70 per cent of the eyes which subsequently developed visual field defects and negative in 75 per cent of those in which no defects developed. Thus the test was neither of diagnostic nor of prognostic value. All the eyes with a positive test which later developed visual field defects had been treated, whereas 57 per cent of the eyes with a negative test which subsequently developed visual field defects had received no treatment. This indicated that a negative water-drinking test gave a false security. It is shown that an alteration of the lower limit of a tension rise does not render the water provocative test any more useful.

Drinking↗