PubMed · 14248652
The source did not provide an abstract. Follow the original record for more information.
Explore connections, maps & timelines
J B DAWSON. 1965-01-23. MODERN URINE TESTING.. https://doi.org/10.5694/j.1326-5377.1965.tb71446.x
Cite the original work for its findings. Save a collection to share your selection of sources.
KEEP EXPLORING
Circular dichroism (CD) is an important spectroscopic technique for monitoring chirality and biological macromolecule conformation. However, during a CD measurement, absorbance, light scattering/turbidity, and fluorescence can also be detected. The simultaneous measurement of these different spectral features for a single sample is the basis of a multi-mode optical spectrometer. This allows time-efficient gathering of complementary information and provides a scheme to ensure that CD measurements are reliable. Aspects of circular polarization differential light scattering, pH, and temperature variation of a protein (antibody) solution are described. A procedure to help ensure that CD measurements are reliable is described.
This paper reviews procedures for quantification of drugs in the biosamples blood, plasma, serum, or oral fluid (saliva, etc.) using liquid chromatography coupled with single-stage or tandem mass spectrometry (LC-MS, LC-MS-MS). Such procedures are important prerequisites for competent toxicological judgment and consultation in clinical and forensic toxicology. They cover blood (plasma, serum) analysis of amphetamines and related designer drugs, anesthetics, anticonvulsants, benzodiazepines, opioids, serotonergic drugs, tricyclic antidepressants, neuroleptics, antihistamines, beta-blockers, muscle relaxants, and sulfonylurea-type antidiabetics, and oral fluid analysis of amphetamines and related designer drugs, cocaine, benzoylecgonine, codeine, morphine, enantiomers of methadone and its main metabolite 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP), the nicotine metabolites cotinine and hydroxycotinine, and finally risperidone and its metabolite 9-hydroxyrisperidone. Basic information on the procedures is given in two tables and an example of quantification is illustrated in two figures. The pros and cons of such LC-MS procedures including sample work-up and ion suppression effects are critically discussed.
The technique of DGT (Diffusive Gradients in Thin Films) was further developed to allow simultaneous measurement of sulfide and trace metals at the same location in sediment. The new combined DGT probe consisted of a layer of gel impregnated with AgI, overlain by (1) a layer of gel containing Chelex, (2) a layer of gel and (3) a filter membrane. Diffusion of sulfide was controlled by layers (1) to (3), while diffusion of metals was controlled by layers (2) and (3). The Chelex gel trapped metals that were measured after elution with acid. The AgI gel trapped sulfide through the formation of Ag2S. This was then measured densitometrically as the colour changed from pale yellow to grey. Experiments demonstrated that concentrations of metal or sulfide measured by the combined device were no different to the concentrations measured by more conventional devices. The presence of Chelex in the gel did not impede the diffusion of sulfide. Deployment of a combined probe in marine sediment revealed simultaneous remobilisation of metals and sulfide at the same location. Solubility calculations indicated that some precipitation of amorphous FeS was probably occurring at the maxima in sulfide concentrations. There was general undersaturation with respect to NiS, but ZnS was supersaturated at all locations. There appeared to be localised active zones of organic matter decomposition, where reduction of manganese oxides, iron oxides and sulfate occurred simultaneously. Mass balance calculations indicated that Ni could not be supplied by release from decomposing organic matter. Manganese oxides were the most likely source, but supply from reductive dissolution of iron oxides could not be entirely discounted. Supply from either Fe or Mn oxides could account for the Zn maxima. Application of the newly developed combined probe provides new information that helps understanding of the complex nature of trace metal and sulfur chemistry in sediments.