Coulter counter technique

The principle of this zone sensing (Coulter Counter ) technique is as follows ... 

Coulter Counter Technique A particle- or droplet-sizing technique in which the flow of dispersed species in a capillary, between charged electrodes, causes changes in conductivity that are interpreted in terms of the sizes of the species. Coulter is the brand name for the automated counter. See also Sensing Zone Technique. 

Processes in Aqueous Systems An Application of the Coulter Counter Technique, presented at IWRA meeting, Chicago, 111., June 1974. 

Gear and Bednarek (1972) have recently adapted a Coulter counter technique to the determination of mitochondrial size and number. Large differences in the size of mitochondria from rat liver, heart, and kidney exist. Cytochrome a - - as, iron content, and cytochrome oxidase activity vary when calculated on the basis of protein, but are much more imiform when considered on a per particle basis. 

The procedures for setting up a mass balance and for mass calibration of the Coulter Counter technique are identical. A weighed amount of sample of known density is suspended in a known volume of electrolyte, a known portion of which is analysed. From these data the total volume of particles in the analysed volume of electrolyte can be calculated and compared with the measured volume of particles. For a mass (or volume) balance this measured volume of particles is calculated by means of a prior calibration, generally with an appropriate latex standard. For mass calibration, on the other-hand the ratio of measured and calculated particle volume is used to correct the prior calibration constant. The following equations can be derived ... 

Various techniques and equipment are available for the measurement of particle size, shape, and volume. These include for microscopy, sieve analysis, sedimentation methods, photon correlation spectroscopy, and the Coulter counter or other electrical sensing devices. The specific surface area of original drug powders can also be assessed using gas adsorption or gas permeability techniques. It should be noted that most particle size measurements are not truly direct. Because the type of equipment used yields different equivalent spherical diameter, which are based on totally different principles, the particle size obtained from one method may or may not be compared with those obtained from other methods. 

While more commonly used to count or otherwise characterize cells for medical applications, Coulter Counters and flow cytometry technique can also be applied to the analysis of pollen grains in allelopathic studies. They are quite useful in determining the size and number of pollen grains. The technique is often used for assessing the production and size of pollen from the originating individual rather than how much was transferred to heterospecific stigma, as would be needed in a basic assessment of potential allelopathic interactions. 

Mineral standards were hand crushed to -1/4 inch, then ground to a fine powder in a ball mill (alumina elements) or Bleuler Model 526/LFS678 puck mill. The resultant powder was aerodynamically classified in a Bahco Model 6000 micro particle classifier and the finest fraction ( 18 throttle) was collected. A size criterion of 90% or more by weight of particles 5 micron and smaller in diameter was used for the mineral standards. Sizes were verified by Coulter Counter. Duplicate 13 mm KBr pellets were prepared and the spectra were weight-scaled by techniques similar to those reported by Painter (3) and Elliot (4). With one exception, all the mineral standard spectra were averages of spectra from duplicate pellets. The one exception was the iron sulfate spectrum, which was obtained as the difference spectrum by subtracting the spectrum of HCl-washed weathered pyrite from that of the weathered pyrite. A weight correction was applied to the difference spectrum. 

This may be due to the fact that the total number of particles is based on 1.2 pm and not 0 pm. The start of nucleation resulted in a large number of nuclei being formed but they were smaller than 1.2 pm. These nuclei were not detected by die current measurement technique. As time proceeded, these nuclei grew in size and more and more of them became detectable by the Coulter Counter used. 

One optical imaging technique that circumvents the problem of multiple fight scattering is to estimate the bubble size distribution from the area individual foam bubbles occupy ai a glass surface. Such experiments, and the systematic differences between bulk and surface bubble distributions, have been reviewed. Another technique that also directly measures the bubble size distribution is ihe use Of a Coulter counter, where individual bubbles are drawn through a small lube and counted. This yields a direct measure of the bubble size distribution, hut it is invasive and cannot probe the structure of the foam. 

Coulter Counter To avoid the tedium of direct microscopic counting, a Coulter counter can be employed. By using this technique, not only the cell number, but the cell size can be measured. The disadvantage of this technique is that it cannot distinguish between cells and any impure particles. The technique is also difficult to use with organisms in chains and is useless with mycelial organisms. 

The Coulter counter affords a convenient indirect technique for... 

An example is the Coulter counter. The term sensing zone technique is also used with reference to similar techniques that use light absorption or scattering instead of electrical properties, see Photozone Counter. 

In many powder additives, the presence of oversize particles results in faults in the finished product. A technique has been developed [65] for determining the number concentration of these oversize particles using the Coulter Counter Multisizer II. 

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