PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Spectrophotometry, Infrared”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed1975

[Infrared spectrophotometry of culture broth and toxins of enteropathogenic strains of Escherichia coli].

Lyophilized preparations of sterile broth, broth used for cultivation of enteropathogenic E. coli strains from which endotoxin and enterotoxin had been removed, were prepared for spectrophotometry by mixture with potassium bromide, and examined in heavy water. Despite basic biochemical differences, all the preparations showed similar or identical curves, with the same absorption maximum and wave length. The substances present in broth (proteins, lipids, sugars, etc.) were so dominant that that completely masked substances specific for E. coli and its toxins. Spectrophotometry revealed only the pattern belonging to broth, so that toxins can be only examined by this method after they have been separated from the broth. It is hoped to do this in the future.

Carbohydrates↗
PubMed1978

[Analysis of gallstones by infrared spectrophotometry. Advantages and limits of the method (author's transl)].

Numerous clinicians criticise the insufficiency and imprecision, and the incoherency of the analyses of biological calculations by the usual clinical methods and thus frequently avoid prescribing such an examination. The authors propose the application of a physical method, infrared spectrophotometry for the qualitative and semi-quantitative determination of the composition of stones of all origins. They recall the often heterogeneous structure of the stones and emphasise the importance which they attribute of differential analysis by separate zones during careful dissection, the results of which may orient the therapeutic attitude of the clinician. The differentiation of a few crystalline structures and the study of complex mixtures are dealt with in the form of characteristic infrared spectra. The advantages and limits of the method compared with other technics of analysis are discussed.

Bilirubin↗
PubMed1975

Interaction of water with egg lecithin in benzene solution.

Benzene solutions of purified egg lecithin, with small amounts of water added, have been examined by 60 MGz and 100 MHz NMR spectroscopy, infrared spectrophotometry and phase contrast microscopy. The transverse relaxation times of the water, N-methyl and O--H protons are dependent on water concentration. This dependence changes sharply for the water proton at a level of one water molecule per lecithin monohydrate molecule. These results do not fully agree with those reported by other workers. Four mathematical models are examined which could account for the behaviour of the water protons. Models which assume a constant transverse relaxation time for water protons above a level of one water molecule per lecithin molecule cannot predict the behaviour observed. It is sufficient to assume that water protons above this concentration have a single relaxation time which is a linear function of water concentration. The added water associates primarily with the phosphate in the lecithin head group. Above nine water molecules per lecithin monohydrate molecule free water is present in the system.

Benzene↗
PubMed1975

The analysis of pharmaceuticals by combined gas chromatography-mass spectrometry. I. The analysis of a medicated aerosol spray.

A medicated aerosol product was qualitatively analyzed by combined gas chromatography-mass spectrometry. The data were processed by a minicomputer. Ten of the 11 peaks in the gas chromatogram were identified with the assistance of the National Institutes of Health/Division of Computer Research and Technology/Chemical Information System mass spectral search system. The unidentified peak is probably a member of the terpene class. The aerosol propellants were also partially analyzed by infrared spectrophotometry.

Aerosol Propellants↗
PubMed1979

25-Hydroxyvitamin D3 26,23-lactone: a new in vivo metabolite of vitamin D.

A major vitamin D metabolite was isolated in pure form from the blood plasma of chicks either maintenance levels or large doses of vitamin D3. The isolation involved methanol-chloroform extraction and five column chromatographic procedures. The metabolite purification and elution position on these columns were followed by a competitive protein binding assay. The metabolite was identified, using high- and low-resolution mass spectrometry, 270-MHz proton nuclear magnetic resonance spectrometry, ultraviolet absorption spectrophotometry, Fourier transform infrared spectrophotometry, and specific chemical reactions, as 3 beta,-25-dihydroxy-9,10-seco-5,7,10(19)-cholestatrieno-26,23-lactone. The trivial names 25-hydroxyvitamin D3 26,23-lactone or calcidiol 26,23-lactone are suggested for this compound.

Animals↗
PubMed1975

Thiopental suicide -- case report.

Thiopental was indicated in the suicide death of a hospital employee. The blood thiopental level was determined to be 27.9 mg% by ultraviolet spectrophotometry, and positive identification was accomplished using gas chromatography, thin-layer chromatography, and infrared spectrophotometry.

Adult↗
PubMed1979

Field evaluation of selected monitoring methods for phosgene in air.

Four selected methods have been evaluated and field tested as candidates for a specific, continuous procedure for monitoring phosgene in air at or below concentrations of 0.05 ppm. The methods evaluated were automated colorimetry, gas chromatography, infrared spectrophotometry and a recently developed paper tape monitor. A standard manual colorimetric procedure was used as a reference method. The paper tape, infrared and automated gas chromatographic techniques most closely fulfilled the criteria set forth for an "ideal", selective, continuous procedure for phosgene.

Air Pollutants↗
PubMed1976

The effect of grinding of human dentine examined by X-ray diffraction, infrared spectroscopy, and electron microscopy.

Analysis of human dentine by infrared spectrophotometry suggests that ball-grinding may result in damage of the apatite crystallites. The present study includes further assessments of this effect by X-ray diffraction, infrared spectroscopy, and electron microscopy. Each of three coarse-ground dentine samples (Group I) was divided into three portions of 30 mg. One of these portions was ball-ground for approximately 1 min (Group II), the second portion for 6 min (Group III), and the third portion for 23 min (Group IV). The 002 reflection showed line broadening, most marked from Group II to III. Electron microscopy showed a gradual change in crystallite appearance with increased grinding, most pronounced from Group II to III. These observations indicate that by prolonged grinding a limit is approached where no further changes in the crystallites occur. Electron microscopy also indicated that fracture of the crystallites might have occurred. This was probably accompanied by strains in the lattice. The infrared spectra indicated that no breakdown of the apatite structure had occurred during the entire grinding.

Apatites↗
PubMed1979

Identification of some benzodiazepines of forensic interest.

Ten benzodiazepines--clorazepate, nitrazepam, clonazepam, oxazepam, lorazepam, chlordiazepoxide, N-desmethyldiazepam, diazepam, prazepam, and flurazepam--in solid dosage form are identified by ultraviolet (UV) and infrared (IR) spectrophotometry and by high pressure liquid chromatography (HPLC). UV absorption data and IR spectra of the 10 benzodiazepines are provided and HPLC separation methods are described.

Benzodiazepines↗
PubMed1977

Benzene toxicity: a critical evaluation: analytical techniques.

The choice of any procedure for analysis involves consideration of a number of factors and is best resolved by professional judgment. In general, techniques that require the fewest steps for sample preparation give the best results and instrumentation should be selected with this in mind. In recent times, the most successful determinations of benzene have used nonvisible spectrophotometry and gas chromatography. These techniques provide good sensitivity and require minimal sample preparation. Spectrophotometric methods are best used where there are few interfering compounds and therefore they are adequate for determinations of benzene in air, water, some industrial gases, and simple solvent mixtures. The development of Fourier transform interfacing has greatly improved the sensitivity of spectrophotometers and allows for improved accuracy using small samples. This has been especially realized in the direct analysis of gases by infrared spectrophotometry. The usefulness of gas chromatography lies in its ability to separate components in a mixture before analysis. For this reason, gas chromatography is the technique of choice for determining benzene in complex gaseous or liquid mixtures and biological systems. The development of microcircuitry has improved detector response as well as reduced the costs of most instruments. This, combined with the availability of prepacked columns, has made the gas chromatograph a standard instrument in even small laboratories.

Air Pollutants↗