Coulter

Figure Bl.26.7. Diagram of a BET apparatus (representing an OMNISORB 100) (Beckman Coulter 1991 OMNISORP Manual).

Cough medicines Coulomb s law Coulometry Coulter principle Coumachlor [81-82-3]... 

M. O. Coulter, Modem Chlor—Alkali Technology, Ellis Horwood, London, 1980. 

Fig. 14. Simplified schematic of an electrozone stream counter, the Coulter Counter (Coulter Counter Electronics, Hialeah, Florida).

The aperture impedance principle of blood cell counting and sizing, also called the Coulter principle (5), exploits the high electrical resistivity of blood cell membranes. Red blood cells, white blood cells, and blood platelets can all be counted. In the aperture impedance method, blood cells are first diluted and suspended ia an electrolytic medium, then drawn through a narrow orifice (aperture) separating two electrodes (Fig. 1). In the simplest form of the method, a d-c current flows between the electrodes, which are held at different electrical potentials. The resistive cells reduce the current as the cells pass through the aperture, and the current drop is sensed as a change in the aperture resistance. 

The automated method differs from the ICSH method chiefly in that oxidation and ligation of heme iron occur after the hemes have been released from globin. Therefore, ferricyanide and cyanide need not diffuse into the hemoglobin and methemoglobin, respectively. Because diffusion is rate-limiting in this reaction sequence, the overall reaction time is reduced from approximately three minutes for the manual method to 3 —15 seconds for the automated method. Reaction sequences in the Coulter S + II and the Technicon H 1 and H 2 are similar. Moreover, similar reactions are used in the other Coulter systems and in the TOA and Unipath instmments. 

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. 

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

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