Six routine techniques for the determination of monoclonal IgM are compared: standard electrophoresis, the Technicon AIP system, Hyland laser nephelometry, Beckman Immunochemistry System, Behring laser nephelometry, and radial immunodiffusion. The data are evaluated by use of a nonparametric statistical analysis of variance by ranks (Friedman test) and Wilcoxon's test. The 27 sera containing mo...

The McFarland method allows the concentration of bacterial cells in a liquid medium to be determined by either of two instrumental techniques: turbidimetry or nephelometry. The microbes act by absorbing and scattering incident light, so the absorbance (turbidimetry) or light intensity (nephelometry) measured is directly proportional to their concentration in the medium. In this work, we develop...

By contrast with photometry (i.e., the measurement of light transmitted through a particle suspension), nephelometry is a direct method of measuring light scattered by particles in suspension. Since the scattered light intensity is directly proportional to the suspended particle concentration, nephelometry is a promising method for recording microbial growth and especially for studying filament...

Fluorescence immunoassay (FIA), a relatively new technique for measuring rheumatoid factors (RF), is automated, quantitative, and calibrated against the Centers for Disease Control reference material for RF. We studied the FIA method in relation to a panel of AF methods, both qualitative [latex (LA) and sheep cell agglutination (SSCA)], and quantitative [nephelometry and enzyme-linked immunoass...

Ideal integrating nephelometers integrate light scattered by particles over all directions. However, real nephelometers truncate light scattered in near-forward and near-backward directions below a certain truncation angle ~typically 7°!. This results in truncation errors, with the forward truncation error becoming important for large particles. Truncation errors are commonly calculated using M...

The performance of the Alfred 60/AST device, an automated bacterial culture device which uses laser nephelometry to detect and quantify bacterial growth, was evaluated. The instrument is effective at screening negative samples and is more reliable at detecting bacteria than yeasts. Microscopy can be used to reduce the false-negative numbers.