Nephelometry method

Decker and Fizet have developed a novel laser nephelometry method for monitoring continuously by the kinetics of facile photopolymerizations. Figure 1... 

Increase of transparency of polymer-oligomer films was observed in the presence of surfactant at C < And the increase of absolute value in this ease was eaused not by improvement of thermodynamie affinity of mixture s components, but by the deerease size of emulsion drops, whieh took plaee in the presenee of surfaetant. This experiment was earried out by the nephelometrie method, which was able to register partieles in a size above 1000 A° only [121], All the heterogeneities and phase formations of smaller size, existing in this system, eannot be captured by this method. 

Description of Method. Adding BaC to an acidified sample precipitates S04 a BaS04. The concentration of S04 may be determined either by turbidimetry or nephelometry using an incident source of radiation of 420 nm. External standards containing known concentrations of S04 are used to standardize the method. 

Turbidimetry and Nephelometry. In contrast to classical absorbance methods, immunoassay reactions frequently involve agglutination in which the optical scatter signal of the agglutinated particles is measured by turbidimetric or nephelometric means. The principles of light scattering as it relates to analytical methods is discussed in reference 6. 

Several sulfate determinations in model solutions and urine samples were earried out. The results are of suffieiently good reprodueibility (within 10% rel.) and are in agreement with gravimetry and nephelometry data. This faet allows us to reeommend this method for express-determination of sulfate in urine. 

Seligson s group (95) has published a similar turbidimetric procedure but used nephelometry to measure continuously the effect of lipase on the light scattering of an olive oil emulsion. The instrumentation and approach is the same as that described above for the nephelometric determination of amylase. The method according to the authors is fast and precise with good specificity and sensitivity. The short time required for analysis makes it suitable for emergency use. The technical simplicity permits this method to be easily automated, and it appears to be the lipase method of choice. 

Bevan, C. D., Uoyd, R. S. A high-throughput screening method for the determination of aqueous drug solubility using laser nephelometry in microtiter plates. Anal. Chem. 2000, 72,1781-1787. 

Part—IV has been entirely devoted to various Optical Methods that find their legitimate recognition in the arsenal of pharmaceutical analytical techniques and have been spread over nine chapters. Refractometry (Chapter 18) deals with refractive index, refractivity, critical micelle concentration (CMC) of various important substances. Polarimetry (Chapter 19) describes optical rotation and specific optical rotation of important pharmaceutical substances. Nephelometry and turbidimetry (Chapter 20) have been treated with sufficient detail with typical examples of chloroetracyclin, sulphate and phosphate ions. Ultraviolet and absorption spectrophotometry (Chapter 21) have been discussed with adequate depth and with regard to various vital theoretical considerations, single-beam and double-beam spectrophotometers besides typical examples amoxycillin trihydrate, folic acid, glyceryl trinitrate tablets and stilbosterol. Infrared spectrophotometry (IR) (Chapter 22) essentially deals with a brief introduction of group-frequency... 

Chapon, L. (1993). Nephelometry as a method for studying the relations between polyphenols and proteins. ]. Inst. Brew. 99, 49-56. 

Kinetic solubility This pragmatic approach starts with a concentrated compound solution in pure DM SO further diluted in a buffer medium. The amount of compound in solution is measured after a few minutes incubation either by recording its UV absorbance (with or without a chromatographic step) or precipitate formation using an optical method (turbidimetry, nephelometry or flow cytometry). This approach mimics the typical path of the compound in biochemical, cellular assays or in vivo animal models. Kinetic solubility usually serves as a quality filter prior to cell based assays (see paragraphs on solubility, permeability and cellular assays). 

The optimum combination of all available methods, including the determination of albumin and IgG by laser nephelometry or by another suitable method (ELISA or particle-enhanced immunonephelometric determination if IgM and IgA), will help in the future to significantly increase the sensitivity of the assays in the CSF diagnostics of multiple sclerosis, thereby improving the correlations between individual examinations. 

Nephelometry, a technique that differs from colorimetry, also uses Beer Lambert s law. This method involves the formation of a precipitate and, based on the absorbed light at a given wavelength, allows the concentration of the precursor... 

Purity was confirmed by gel-filtration using a HPLC column packed with Asahipak GS-520HQ and elution with 100 mM sodium phosphate buffer containing 300 mM sodium chloride (pH 6.7). The content of total protein, total sugars, uronic acids, sulfates, nucleic acids, phosphate or fatty acids was assayed by the BCA [32] and Lowry method [33], the phenol-sulfuric acid method [34], the Blumenkrantz method [35], nephelometry [36], absorption at 260 nm, the Bartlett method [37] and the GLC method after methyl-esterification [38], respectively. 

Adsorption of surfactants "Loss from solution" method, direct measurement using radioactive tracers, ellipsometry, nephelometry... 

Schultz-Ellison, G., Charland, C., Driscoll, J., and Thayer, W., A rapid method for immune complex detection PEG insolubilization combined with laser nephelometry. /. Immunol. Methods 31, 31-40 (1979). 

The majority of assay methods for excreted low molecular weight proteins are based in immunometric methods (gel immunodiffusion, nephelometry or ELISA) and the antibodies do not cross-react with homologous proteins in animal urine (the exception is p2 -microglobulin, for which a rat-specific latex... 

Bevan CD (2000) A High-throughput Screening Method for the Determination of Aqueous Drug Solubility Using Laser Nephelometry in Microtiter Plates. Anal Chem 72 1781-1787... 

The method of Baltzer (B7) yields better results. It consists of precipitating mucin with a mixture of sulfosalicylic acid and acetone and determining the reducing power of the precipitate. The obtained value is corrected for protein content, determined nephelometrieally by sulfosalicylic acid precipitation. 

In solution, glycogens interact with certain proteins (for example, serum albumin and globulin, and myosin) to form complexes which may be examined by such physicochemical methods as ultracentrifugal analysis, nephelometry, ultraviolet spectrophotometry, and electrophoresis. Since glycogens have a higher affinity for myosin than < -dextrin (muscle... 

The quantitation of enzymes and substrates has long been of critical importance in clinical chemistry, since metabolic levels of a variety of species are known to be associated with certain disease states. Enzymatic methods may be used in complex matrices, such as serum or urine, due to the high selectivity of enzymes for their natural substrates. Because of this selectivity, enzymatic assays are also used in chemical and biochemical research. This chapter considers quantitative experimental methods, the biochemical species that is being measured, how the measurement is made, and how experimental data relate to concentration. This chapter assumes familiarity with the principles of spectroscopic (absorbance, fluorescence, chemi-and bioluminescence, nephelometry, and turbidimetry), electrochemical (poten-tiometry and amperometry), calorimetry, and radiochemical methods. For an excellent coverage of these topics, the student is referred to Daniel C. Harris, Quantitative Chemical Analysis (6th ed.). In addition, statistical terms and methods, such as detection limit, signal-to-noise ratio (S/N), sensitivity, relative standard deviation (RSD), and linear regression are assumed familiar Chapter 16 in this volume discusses statistical parameters. 

Turbidimetry and nephelometry are methods used to measure scattered light. Their measurement has proven useful for the quantitation of serum proteins (see Chapters 9 and 20). 

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