Size methods turbidimetry

Turbidimetry measurements, using monochromatic light, yields data that can be used to determine particle size distributions. It requires simple optical technology, but complex computational software to handle the Mie theory conversion. The sensitive diameter range for latex-water suspensions was found to be 0.1 to 10 pm. Different types of sensors have been conceived and applied to various experimental situations. The method is particularly useful in crystallization experiments. Other applications include agglomeration, attrition and nucleation studies. Applications of the equipment and software to studies of emulsions, fumes and aerosols are also envisaged [18]. 

Immunochemical methods are also used for clinical assays because they are rapid and easily automated. Because of the differences in molecular size and corresponding diffusion rates, gel diffusion techniques, such as radial immunodiffusion (RID) require correction for phenotype and are therefore time consuming and inconvenient. Immunoassays in solution, such as nephelometry and turbidimetry, are influenced slightly by size as well, but the differences are relatively insignificant. 

In summary, the simplicity of measurement makes turbidity spectra methods attractive for on-line monitoring of particle size distribution, particular / if the distribution is known to be monomodal. In this case average particle size, determined by turbidimetry may be sufficient for continuous monitoring and control. This has been shown by Hamielec and coworkers (10) who, by techniques of state estimation, have used turbidity data to estimate other states of an emulsion system, and applied closed-loop control accordingly. 

Standard deviations were higher when induction times were measured by microscopy. Significant differences between methods were detected (P < 0.01). Induction times determined by microscopy were not equivalent to those measured by laser turbidimetry. Crystals must reach a minimum size of 0.2 pm to be detected by microscopy, whereas the laser turbidimetric technique is able to detect smaller nuclei [5]. 

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