Method and device for determining absolute number densities of particles in suspension

A particle and number technique, applied in the field of determining the number and density of particles in a solution, which can solve the problems of low accuracy, time-consuming, difficulty in determining absolute particle number and distribution

Active Publication Date: 2005-04-27
WYATT TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0006] Unfortunately, determining absolute particle counts and distributions has been difficult and time-consuming
The ne

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  • Method and device for determining absolute number densities of particles in suspension
  • Method and device for determining absolute number densities of particles in suspension
  • Method and device for determining absolute number densities of particles in suspension

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Embodiment Construction

[0021] The invention is readily understood by reference to a monodisperse aqueous suspension of uniform spherical particles. Despite their simplicity, such samples are among the most common and important examples where absolute particle number densities need to be determined. Examples of such samples include familiar polystyrene emulsions, or PSL spheres, such as those manufactured by Duke Scientific Corporation of Palo Alto, CA, and JSR Corporation of Tokyo, Japan. Such PSL samples are noted with their average size and mass fraction. Generally, for particles whose diameter is below 1000 nm, the mass of PSL spheres per milliliter of solution is expressed in %, ie 1% means 1 gram (gm) of PSL spheres per milliliter (ml) of solution. Therefore, the calculation of the actual number density present in each milliliter of solution requires prior knowledge of the average particle size, the PSL mass density, which is about 1.05, and the percentage of PSL representing grams of PSL per ...

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PUM

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Abstract

A method for determining absolute number densities of particles in a solution is disclosed based on a light scattering method. A light scattering photometer is calibrated to produce the Rayleigh ratio at each angle measured with respect to light scattered per unit incident intensity, per unit volume illuminated within the field of view of each detector per steradian subtended by said detector. In order that the numbers calculated be accurate, the illuminated particles should be effectively monodisperse. From the excess Rayleigh ratios measured at a plurality of angles with respect to the incident light beam illuminating said sample particles, an effective size is calculated which, in turn, is used to calculate the differential scattered intensity at each angle. The number of particles per unit volume element is then determined from the measured excess Rayleigh ratio divided by the corresponding differential scattered intensity.

Description

technical field [0001] The present invention relates to methods and apparatus for determining the number of particles, and more particularly to methods and apparatus for determining the number density of particles in a solution using light scattering measurements. Background technique [0002] Determining the absolute number of particles in a liquid suspension is an important requirement for many types of particle-based applications. In the field of medicine, for example, particles such as liposomes, microcapsules, viruses and emulsions are often used for the delivery of conjugated drugs or agents. The therapeutic benefit of these particulate drugs relies on prior knowledge of the amount of drug being released, which requires accurate measurement of the number of particles per unit volume delivered to the patient. [0003] For viral vectors, such as genetically engineered parvoviral capsids and viruses designed to introduce heterologous genes into target cells, as described...

Claims

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Application Information

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IPC IPC(8): G01N15/06G01N15/02G01N21/51
CPCG01N21/51G01N2030/003
Inventor P·J·怀亚特M·J·韦达
Owner WYATT TECH
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