Electronic particle counter

P. W. HeUeman, The Coulter Electronic Particle Counter. Aspects and Views in Counting and Si ng oJErythroytes,D>Qi Bilt HoUand, the Netherlands, 1972, Chapt. 7-11. 

Fig. 1.13 Principle of electronic particle counter Coulter counter. 

A miniaturized version of the conventional flask method with S. capricomutum has been developed by Blaise et al [136]. In this assay the algae are exposed to the toxicant in 96-well microplates for a period of 96 hours, after which the cell density is determined using a hemocytometer or electronic particle counter. ATP content measurements [136] or chlorophyll fluorescence [141,142] have also been proposed as test criteria. Compared to the flask method, the main advantages of the microplate assay are (a) the small sample volumes and reduced... 

Cell concentration in suspension can be determined through an optical microscope employing a hemocytometer for manual cell counting, or in a semi-automatic way using an electronic particle counter (such as a Coulter counter), as described in detail by Freshney (2005). Through dye exclusion (such as trypan blue), it is possible to determine viable cell concentration, that is the number of cells in a known sample volume capable of proliferating in favorable culture conditions. 

Depending upon the test organism, between 2 X 104 and 5 X 104 cells are used to inoculate the test vessel and the concentration of cells is determined daily. Cell counts are made daily by using a hemocytometer or an electronic particle counter such as the Coulter Counter. Chlorophyll can be measured spectrophotometrically or fluorometrically. The fluorometric determinations are more accurate at low concentrations of test organism. Other measurements that have been used include DNA content, ATP charge, and 14C assimilation. 

Testkits ALGALTOXKIT F (MicroBioTests Inc., Nazareth, Belgium). Specific equipment device for determination of cell concentration (e.g. electronic particle counter, microscope with counting chamber, fluorimeter, spectrophotometer, colorimeter). 

The third and final particle size distribution model assumes that growth is linear as in the first but that breakup results in predominantly small particles (thorough breakage) which are too small to measure by the electronic particle counters used to characterize the suspension. Petenate and Glatz (6) have provided analytical solutions for this model. 

Particle Size Distributions Via Electronic Particle Counters... 

Although the coalescence assumption may lead to small errors in the scattering cross section, it does enable the rapid correlation of turbidity data (n) with electronic particle counter data (n and fi), provided the relative refractive index and size regime are known. Because the electronic particle counter measures the aggregate volume, and therefore determines only an equivalent spherical radius, the data from the electronic particle counter relate only to the coalesced-sphere approach. 

Application of Electronic Particle Counters, Environ. Sci. Technol. 1977,11, 707-714. 

The new classes of highly abundant particles, which had remained undetected by traditional oceanographic techniques [12] because of their small size, consistency, or transparency, were recently identified using electronic and electrochemical particle counters, electron microscopy, and histological staining techniques. These new particle classes are defined operationally in Table 1. 

Electronic particle (Coulter) counters have been used for counting bacteria and yeasts. Major users are in the wine and beer industries. The problems with this method are that it is non-specific, and there are considerable difficulties in preparing samples which are free of dust and detritus as these may cause erroneous high counts. 

Figure 3. Pints of mean particle size versus standard deviation of two prepared mixtures of standards analyzed by selected automated electronic particle size analysers (from Syvitski et al 1991a). The expected value is shown with a black box. S SediGraph C. Coulter Counter M Malvern laser panicle. sizer G Galai CIS-1, L Lumosed photosedimentometer lA Image analysis (Syvitski et al.. 1991a).

One of the earliest electronic particle sizing devices available was developed in the late-1940 s and was originally designed to count blood cells (Coulter, 1956). The Coulter Counter rapidly gained immense popularity in many industry and research applications, including the Earth sciences, and is still a very commonly used instrument in sedimento-logical laboratories. The Coulter Principle is sufficiently well established to be included in many A.S.T.M. (American Society for Testing Materials) reference method standards. 

S Chandler, L Trissel, L Wamsley, J Lajeunesse, R Anderson. Evaluation of air quality in a sterile-drug preparation area with an electronic particle counter. American Journal Hospital Pharmacy 50 2330-2334, 1993. 

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