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At least 109 records · Page 6Linked to original sources
PubMed1981

[Identification of drugs in toxic doses in biological fluids using infrared Spectrophotometry].

A method permitting rapid analysis of biological samples from patients suspected of being intoxicated is reported. The method is based on: a) extraction of the active principles of biological samples with chloroform; b) drying and preparation of a disc of KBr; c) spectrophotometric analysis; d) integration of data from laboratory analyses with the clinical data from the patient. A number of clinical cases are also reported in which adoption of the method permitted rapid diagnosis of the possible aetiology of the toxic pictures observed.

Body Fluids↗
PubMedDate not supplied

Determination of trans unsaturation by infrared spectrophotometry and determination of fatty acid composition of partially hydrogenated vegetable oils and animal fats by gas chromatography/infrared spectrophotometry: collaborative study.

An infrared spectrophotometric (IR) method for the determination of total trans unsaturated fatty acid (trans) content and a combined gas-liquid chromatographic/infrared spectrophotometric (GC/IR) method for determination of fatty acid composition of partially hydrogenated vegetable oils (PHVO) were studied collaboratively in 12 laboratories using 7 PHVO samples, including 1 pair of blind duplicates. The test samples were methylated and analyzed for total trans content by IR and for fatty acid composition by GC/IR using a capillary column coated with SP-2560 or another suitable cyanoalkylsiloxane stationary phase. From the measured IR absorption, the isolated trans content was calculated using a calibration curve of absorption versus trans content developed with 2-component calibration standard mixtures of methyl elaidate and oleate. The GC provided the levels of mono-trans-octadecadienoates (18:2t), di-trans-octadecadienoates (18:2tt) and mono-trans-octadecatrienoates (18:3t). The trans-octadecenoate (18:1t) content was calculated with the formula: 18:1t = IR trans-0.84 x (18:2t + 18:3t) - 1.74 x 18:2tt. The cis-octadecenoate (18:1c) content was obtained as the difference between total octadecenoates (18:1) and 18:1t. Reproducibility relative standard deviations (RSDR) for 15 to 35% trans content determined by IR were in the range of 8.8-11.7%, whereas RSDR for the test sample with 5% trans content was 34.6%. RSDR values for 18:1t by the GC/IR followed the same pattern as that of IR trans values: 36.4% for the test sample with 4.9% 18:1t versus 7.8-12.5% for test samples with 14.9 to 32.6% 18:1t. The content of 18:1c in the test samples varied from 24.7 to 34.5% and their RSDR values ranged from 3.8 to 10.5%. The mean values for 18:1t and 18:1c compared favorably with the absolute levels determined by a silver nitrate-thin layer chromatography/GC procedure. The IR and GC/IR methods are recommended for determination of trans content and fatty acid composition, respectively, of partially hydrogenated fats derived from vegetable oils, terrestrial animal fats or such oils and fats isolated from food products containing > 5% trans fatty acids. For samples containing < or = 5% trans fatty acids, a direct GC method (American Oil Chemists' Society Official Method Ce 1c-89) is available for determination of both trans content and fatty acid composition, because at lower trans levels, overlap of 18:1 cis and trans isomers on GC with very polar capillary columns is negligible.(ABSTRACT TRUNCATED AT 400 WORDS)

Chromatography, Gas↗
PubMed1999

The influence of a clear layer on near-infrared spectrophotometry measurements using a liquid neonatal head phantom.

It is difficult to test near-infrared spectrophotometry instruments in vivo. Therefore we constructed a liquid phantom which mimics the neonatal head. It consists of a spherical 3.5 mm thick layer of silicone rubber simulating skin and bone and a 0.5 mm thick clear layer of polypropylene imitating cerebrospinal fluid. It acts as container for a liquid solution with Intralipid, 60 micromol l(-1) haemoglobin and yeast. The solution was oxygenated using oxygen and then deoxygenated by the yeast. From the instrumental (Critikon 2020) algorithm, we found that with increasing scattering (0.5%, 1%, 1.5% and 2% Intralipid concentration) the reading was increasingly offset from the expected value of 0 micromol l(-1) by 55.7, 68.6, 76.5 and 80.4 micromol l(-1) (oxyhaemoglobin) and 16.0, 24.4, 29.6 and 31.7 micromol l(-1) (deoxyhaemoglobin). This reduced the range of the oxygen saturation reading from the expected 100% to 31.5, 21.1, 14.3 and 11.5%. Haemoglobin concentration changes were increasingly underestimated by a factor of two to four. For a second algorithm based on the diffusion approximation the offsets were smaller: oxyhaemoglobin 11.4, 17.8, 22.5 and 25.1 micromol l(-1) and deoxyhaemoglobin 1.3, 3.4, 5.2 and 6.0 micromol l(-1). The range of the oxygen saturation reading was higher: 41.3, 29.2, 23.4 and 16.6%. Concentration changes were underestimated by a factor of six to ten. This study demonstrates the need to develop algorithms which take into consideration anatomical structures.

Algorithms↗
PubMed1976

Detection of volatile solvents in gastric contents by gas phase infrared spectrophotometry.

A standard procedure for the identification of volatile solvents in the gas phase by infrared spectrophotometry has been modified and applied to the analysis of gastric contents. A 10 ml sample of the vapor from the gastric aspirate is removed with a hypodermic syringe, injected on a spectrophotometer from 2.5 to 15 nm. The sample is then identified by comparison with known reference spectra. Solvent concentrations cen be estimated by comparing the ratios of the major peaks.

Biopsy, Needle↗
PubMed1996

Analysis of breath alcohol via infrared spectrophotometry: predicting false ethanol results by application of the base-line method to vapor phase infrared spectra.

Toluene and a mixture of the isomeric xylenes are common organic solvents that have been implicated in false ethanol results produced by older models of the Intoxilyzer 5000, a breath alcohol analyzer that uses infrared spectrophotometry to quantitate ethanol in breath samples. A straightforward method is described which predicts this type of interference in analyses conducted on such models. The methodology relies on a comparison of the vapor phase infrared spectra of toluene and xylene with the corresponding spectrum of ethanol, using the base-line method to estimate relative absorbances at the two analytical wavelengths employed by the Intoxilyzer 5000. The point is also made that, given the potential for such interference, a model of the Intoxilyzer 5000 has been developed that has the capability to compensate for this problem.

Breath Tests↗