From a hemocytometer count, if a technician makes a 1:4 dilution and counts 100 WBCs in 10 squares, what is the WBC concentration?

To determine the WBC concentration from the hemocytometer count, it is essential to understand the calculations involved.

The number of white blood cells (WBCs) counted in the hemocytometer is 100 in 10 squares, which averages to 10 WBCs per square. Given that the hemocytometer typically uses a volume of 0.1 µL for each counting area, the total volume counted is 1.0 µL (as there are 10 squares counted, each being 0.1 µL).

First, calculate the concentration of WBCs in the undiluted sample:

1. Counted WBCs: 100 WBCs in 1.0 µL.

2. This leads to a concentration of 100 WBCs/µL.

Since the sample was diluted in a 1:4 ratio, this means that the concentration in the original sample is four times greater than what has been counted.

Thus, the original WBC concentration can be calculated as follows:

• Original concentration = 100 WBCs/µL * 4 = 400 WBCs/µL.

To convert this to cells per liter (which is typically how WBC concentrations are expressed