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PubMed2004

Determination of trace amounts of phosphate by flow-injection photometry.

This paper describes a simple and rapid procedure for determination of traces of phosphate by means of molybdenum blue chemistry. The use of a cost-effective home-made flow cell with a long path length in combination with a light emitting diode (LED) and a photodiode (PD) is demonstrated as a simple absorbance detector for flow-injection analysis. In this method, a sample is injected into the carrier stream through an injection valve and mixed online with mixed reagent (a mixture of molybdate, bismuth, and ascorbic acid in sulfuric acid). The color intensity of the resulting association complex, molybdenum blue, is measured photometrically ( lambda(max) 875 nm). The proposed method can be used to detect phosphate in the range 0.02-4.0 mg x L(-1) and the precision of the proposed procedure is less than 5% at 0.1 mg x L(-1) phosphorus as phosphate. The method has been successfully applied to a variety of natural water samples.

Journal Article↗
PubMed1995

Comparison of the carbohydrate biological response modifiers Krestin, schizophyllan and glucan phosphate by aqueous size exclusion chromatography with in-line argon-ion multi-angle laser light scattering photometry and differential viscometry detectors.

A major barrier to the development, preclinical and clinical application of natural carbohydrate biological response modifiers has been the difficulty involved in accurately characterizing carbohydrate polymers with molecular masses ranging from 10(4) to 10(7) g/mol. Herein, we employed size exclusion chromatography with multi-angle laser light scattering and differential viscometry to compare and contrast structural properties of the biological response modifiers Krestin, schizophyllan and glucan phosphate. Krestin, schizophyllan and glucan phosphate exhibit significant differences in molecular mass moments, molecular mass distribution, polymer sizes, intrinsic viscosity and perhaps their solution behaviour. This knowledge of precise physicochemical data is required for a better understanding of the properties and higher structure of complex carbohydrate biological response modifiers.

Chromatography, Gel↗
PubMed2004

Aggregation and other intermolecular interactions of biological buffers observed by capillary electrophoresis and UV photometry.

Electrophoretic and photometric experiments strongly indicate that monovalent anions, which arise by deprotonation of the nitrogen atom in zwitterionic Good's buffers 3-(cyclohexylamino)-2-hydroxy-1-propanesulfonic acid (CAPSO) and 3-morpholinopropanesulfonic acid (MOPS), spontaneously aggregate. Cationic migration of sanguinarine (SA) and chelerythrine (CHE) in highly alkaline 1,3-bis[tris(hydroxymethyl)methylamino]propane (Bis-Tris-propane), in which the concentration of cations of both alkaloids is negligible, may be explained by the existence of an aggregate, which contains uncharged sanguinarine or chelerythrine and one monovalent cation of Bis-Tris-propane at least. Tendency of tris(hydroxymethyl)aminomethane (Tris), bis (2-hydroxyethyl)iminotris(hydroxymethyl)methane (Bis-Tris) and Bis-Tris-propane cations to ion pairing with synthetic cluster borane anions and with fused silica markedly rises up with the size and charge of these cations. The drop in mobility of cluster borane compounds sometimes exceeds 50% of their mobility found at identical pH and ionic strength in buffers with sodium cation. The electroosmosis drop approached 70% if background electrolyte contained Bis-Tris-propane cations instead of sodium cations. Nitrate, taken as a model inorganic ion, and four randomly chosen organic anions interacted markedly less with Tris, Bis-Tris and Bis-Tris-propane cations than cluster borane anions. 2-(N-morpholino)ethanesulfonic (MES) acid anions present in background electrolyte affect the ion pairing of Tris, Bis-Tris and Bis-Tris-propane cations with anionic analytes and, in this way influence also mobilites of these anionic analytes. Limited hydrophilicity at least one of interacting species appears to be the most probable cause of observed intermolecular interactions of biological buffers.

Alkaloids↗
PubMed2004

Single particle light-scattering photometry--some fields of application.

Present developments in the field of bioscience will profit from the fabrication of multilayer films of polyelectrolytes on colloids as well as of nano- and microsized capsules. The single particle light-scattering technique is suitable for process control. This paper describes the mode of operation and efficiency of a laboratory-built single particle light-scattering photometer, which opens up new possibilities in applications, especially in the field of bioscience. This has been achieved by improving the measurement capabilities of organic particle sizes near 100 nm and precision of thickness changes of about 0.5 nm. Besides the classic applications, such as particle size distribution measurements at high resolution and the coagulation kinetics of colloids, the measurement of the layer-by-layer polyelectrolyte adsorption at colloid particle surfaces and the fabrication of colloidal carriers is introduced. The described method is also a precise method for controlling the removal of the latex core to obtain multilayer microcapsules.

Journal Article↗
PubMed1997

Characterization of antigen-antibody complexes by size-exclusion chromatography coupled with low-angle light-scattering photometry and viscometry.

In this paper, the molecular masses (M(r)s) of the complexes of monoclonal anti-BSA (antibody to bovine serum albumin) (clone: 33) and monomer BSA were determined on-line by using size-exclusion chromatography (SEC) coupled with a low-angle laser light-scattering (LALLS) detector and two concentration detectors, ultraviolet (UV) and refractive index (RI) (SEC-LALLS/UV/RI system). Also, the size and M(r)s of the complexes were evaluated by the SEC-LALLS/UV/viscometer (VISC) system. This study demonstrated that, for small size macromolecules, the combination of light scattering and viscosity detection was a suitable choice for determining their M(r)s and sizes.

Antibodies, Monoclonal↗
PubMed2004

Evaluating the efficiency of coagulation in the removal of dissolved organic carbon from reservoir water using fluorescence and ultraviolet photometry.

The present study used ultraviolet absorption (UVa) and the florescence intensity (FI) to evaluate the coagulation efficiency for removing dissolved organic carbon (DOC) in the raw water from Min-Ter, Li-Yu-Ten and Yun-Ho-Shen reservoirs in Taiwan. The results indicated that the ratio of DOC removal rate and FI removal rate was maintained at about 1 at various coagulant dosages. However, the ratio of DOC removal rate and UVa removal rate decreased as the coagulant dosage increased. In addition, after coagulation, the use of florescence intensity instead of total organic carbon (TOC) is better than UVa for measuring the DOC removal rate of the raw waters gathered in different months from the three reservoirs. Furthermore, a good linear relationship between florescence intensity and DOC removal rate was observed, and the DOC/FI ratio of raw water from each reservoir can be used to predict the DOC residual concentration after enhanced coagulation. This result shows that fluorescence analysis can be used for on-line and continuous monitoring the effectiveness of organic matter removal in water treatment.

Alum Compounds↗
PubMed2004

No stellar p-mode oscillations in space-based photometry of Procyon.

Pressure-driven (p-mode) oscillations at the surface of the Sun, resulting from sound waves travelling through the solar interior, are a powerful probe of solar structure, just as seismology can reveal details about the interior of the Earth. Astronomers have hoped to exploit p-mode asteroseismology in Sun-like stars to test detailed models of stellar structure and evolution, but the observations are extremely difficult. The bright star Procyon has been considered one of the best candidates for asteroseismology, on the basis of models and previous reports of p-modes detected in ground-based spectroscopy. Here we present a search for p-modes in 32 days of nearly continuous photometric satellite-based observations of Procyon. If there are p-modes in Procyon, they must have lifetimes less than 2-3 days and/or peak amplitudes <15 parts per million, which defy expectations from the Sun's oscillations and previous theoretical predictions. Target selection for future planned asteroseismology space missions may need to be reconsidered, as will the theory of stellar oscillations.

Journal Article↗
PubMed1989

[Fluorescence photometry study of the normal rat retina before and following fluorescein administration].

Semiquantitative fluorescein photometric studies were performed on the retinas of lyophilized rat eyes. Before injecting the fluorescein, the right, dyeless eyes were enucleated under anesthesia with ketamine hydrochloride. The left eyes were removed between 20 seconds and two hours after intravenous injection of fluorescein. Histologic sections of each of the posterior segments were measured fluorophotometrically. The photometric values of most of the fluorescein-dyed retinal sections were higher than those of the contralateral (dyeless) control eyes. With increasing duration of observation the differences between the sections which contained fluorescein and those which did not diminished, although some temporary and limited increases occurred. The higher extinction values of the specimens containing fluorescein are in agreement with the quantitative results of Grimes et al. (1982), who found fluorescein in all retinal layers. Anesthesia-induced acidoses cannot be ruled out may be considered minimal. The information value of quantitative and semiquantative results is certainly superior to qualitative results is certainly superior to qualitative findings.

Animals↗
PubMed1972

Surface photometry of celestial sources from a space vehicle: introduction and observational procedures.

Diffuse celestial sources of relatively low surface brightness such as the Milky Way, zodiacal light, and gegenschein (or contre lumière) can be studied most reliably from above the earth's atmosphere with equipment flown in artificial satellites. We review the techniques used and some of the difficulties encountered in day-time observations from satellites by the use of a special photometer and polarimeter flown in the orbiting skylab observatory, OSO-6.

Journal Article↗