Patent ID: 7214541

Claim:
A method for improving the precision in counting the number of particles or cells suspended in a given volume of a test sample wherein the number of particles or cells ranges from low particle/cell counts to high particle/cell counts, comprising: a) delivering a sheath stream of the test sample at a first volumetric flow rate to a particle counting means to count the number of particles or cells in the test sample, wherein the sheath stream has a cross-sectional diameter adapted to deliver to said particle counting means substantially one particle or cell of the test sample at a time; b) making an initial count at the first volumetric flow rate of the particles or cells of said test sample per unit time with said particle counting means; c) comparing the initial count of the number of cells or particles in the test sample to a reference value; d) adjusting the flow rate of the test sample to a second volumetric flow rate based on the comparative number of cells or particles in the test sample to the reference value, thereby improving the precision of the particle counting means in counting the number of cells or particles in the test sample.