Measuring cell populations: which instrument can measure both cell number and approximate cell size (volume) in a suspension with high throughput?

Introduction / Context:
Quantifying microbial or cell suspensions is essential for growth studies, vaccine production, and bioprocess control. Several tools exist, ranging from manual counting chambers to automated electronic systems. Knowing which tool provides both counts and size information guides instrument selection in labs and fermentation suites.

Given Data / Assumptions:

• The task is to measure both the number of cells and an estimate of cell size (volume).
• Suspension is amenable to electronic sizing/counting.
• We compare manual and automated approaches.

Concept / Approach:
A Coulter counter measures particles passing through a small aperture with an applied electric field. Each particle displaces electrolyte, causing a change in electrical resistance that is proportional to particle volume. This produces both a count and an approximate size distribution. In contrast, a hemocytometer or a Petroff-Hausser chamber enables manual counting under a microscope, providing counts but not precise, automated size distributions.

Step-by-Step Solution:

Verification / Alternative check:
Instrument specifications from Coulter devices show histograms for particle size and total counts per unit volume, confirming dual capability.

Why Other Options Are Wrong:

• Hemocytometer: manual counting grid; no direct electronic sizing output.
• Petroff-Hausser chamber: similar to hemocytometer for bacteria; provides counts only.
• None of these: incorrect because the Coulter counter satisfies the requirement.

Common Pitfalls:
Assuming microscope-based methods easily provide size; while you can estimate dimensions microscopically, it is not equivalent to automated volume histograms produced by Coulter systems.

Final Answer:
coulter counter