PubMed Health⌕ Search
Home/Archive/PubMed

PubMed · 524044

Techniques for quantitative organic analysis in microdroplets.

R Beeuwkes
View original source ↗Export metadata ↓

Abstract

Techniques are described for the chemical analysis of urea by means of X-ray microanalysis. A selective labelling reagent, thioxanthen-9-ol, is used to precipitate urea together with a sulfur label. Reagents are added to and removed from microdroplets of 50 picoliter volume by means of oil-water partition. The sensitivity of the method is less than 1 picomole. The possibility of extension of these techniques to other analyses is discussed.

Explore related subjects

Chemical PhenomenaChemistryCrystallizationElectron Probe MicroanalysisMicrochemistryOilsUreaXanthenesJournal ArticleResearch Support, U.S. Gov't, P.H.S.

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

R Beeuwkes. 1979. Techniques for quantitative organic analysis in microdroplets.. https://pubmed.ncbi.nlm.nih.gov/524044/

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed1992

1H NMR investigation of manganese peroxidase from Phanerochaete chrysosporium. A comparison with other peroxidases.

1H NMR spectra at 200- and 600-MHz of manganese peroxidase from Phanerochaete chrysosporium and of its cyanide derivative are reported. The spectrum of the native protein is very similar to that of other peroxidases. The assignment of the spectrum of the cyanide derivative has been performed through 1D NOE, 2D NOESY, and COSY experiments. This protein is very similar to lignin peroxidase, the only meaningful difference being the shift of H delta 2 of the proximal histidine. The spectra of the cyanide derivative of these two proteins are compared with those of horseradish peroxidase and cytochrome c peroxidase. The shift pattern of the protons of the proximal histidine is discussed relative to the structural properties which affect the Fe3+/Fe2+ redox potential.

Chemical Phenomena↗
PubMed1992

Interaction of oxidized low density lipoproteins with both apo B,E and scavenger receptors. A model for its production in vitro.

Oxidation of low density lipoprotein (LDL) has been demonstrated in vivo and directly implicated in the process of foam cell formation. Consequently, a considerable research effort has been devoted to the assessment of the metabolic behaviour of oxidized LDL. We have developed a simple and reproducible model to obtain oxidized LDL consisting of the dialysis of LDL (4 g/l) contained in a cellulose bag against 5 litres of 0.15 M NaCl, 5 microM CuSO4, 0.6 mM FeCl3, pH 7.4, 37 degrees C with constant oxygen bubbling. While the resulting particles have a number of physicochemical properties suggesting lipid oxidation, neither apo B fragmentation nor modification in the size and shape were observed. This oxidized LDL showed internalization into cells through both the apo B,E and the scavenger receptors and the rate of removal from the plasma in injected rats was faster than that observed for normal LDL. We suggest that these particles may represent an equivalent to the circulating oxidized LDL postulated in humans.

Chemical Phenomena↗
PubMed1992

Partitional and motional properties of a spin-labeled daunomycin in lipid bilayers. An ESR study.

The partition coefficient of a spin-labeled daunomycin (DAU-SL) in dimyristoylphosphatidylcholine membrane has been determined using the electron spin resonance (ESR) method. The experiment was carried out as a function of temperature between 5 degrees C and 35 degrees C, giving partition coefficients between 2 and 6 without abrupt change at the phase transition. The thermodynamic parameters on transferring the DAU-SL from the aqueous phase to the lipid bilayer were also calculated. The calculated values are: delta H = 6.11 kcal/mol and delta S = 23 cal/K mol. The partitioning of the DAU-SL and its motion in the membrane were investigated in a wide range of pH (4-10.3). The data show that pH has no effect on partitioning of the DAU-SL which suggest that the drug exists in the uncharged form in the bilayer.

Chemical Phenomena↗