Cell Counter Buying Guide

Transcription

1 Cell Counter Buying Guide The 10 things to take into account when buying a cell counter. 1. Type of device The most common devices are: - Hemocytometer. The most common device since the XIX century. A crystal washable chamber that is placed under the microscope. Although very cheap, this method is timeconsuming and user-dependent. - Flow cytometer. Broadly used in the life science s industry and academia. It provides reproductive results, but it has a high acquisition and maintenance cost. - Automated cell counter. Automated Cell Counters have a lower price tag than flow cytometers, with many of its advantages: user independence, and speed. - Spectrophotometer. For certain applications, the concentration of cells existing in a recipient can be approximated using the amount of light that goes thru the recipient. The main disadvantages are the lack of detailed information about the sample, and the error generated

2 2. Washable or disposable chambers? (only for automated cell counters) Cell counters can work with washable or disposable cell counting chambers. With disposable chambers, the lab technical loads the sample, performs the cell counting and disposes the chamber afterwards. Disposable chambers cost between $0,6 to $2,5 per counting, and each chamber can be used for 1 to 10 counts, depending on the manufacturer. 3. Cell diameter counting range? Depending on the type of cell or micro-organism, a different device will be needed. Most devices work in the range of µm, that is the size of mammal cells. If we need to count micro-algae, bacteria, or other smaller we should pay special attention to this feature. However, it is highly recommended to check the lower diameter limit and upper diameter limit with the real device (especially for flow cytometer and automated cell counters). Some devices tested did not perform well when the device was working at those limits.

3 4. Cell concentration counting range? The cell concentration range it is also an important characteristic to take into account. Having a broader range allow laboratory personnel to count directly most of the samples, without having to DILUTE or CONCENTRATE the sample, if it does not fall in the range. 5. Reagents (Only for Flow Cytometers) Take into account the periodic cost of reactives when buying your cell counting device. They add up to the ownership cost, and the recurrent cost of material for your lab. Haemocytometer, Automated Cell Counters and Spectrophotometers do not have reagents cost. 6. Maintenance and Calibration Most cell counter devices require periodic maintenance and calibration. Without the proper maintenance the system will not provide accurate data. It is wise to take into account these expenses when calculating the ownership cost of the device. Additionally, flow cytometers are a complex machine with several pumps and liquid circuits. They tend to break up and need higher maintenance than other devices.

4 7. Set-up Time Set-up time is the preparation time the device needs in order to start working. Flow cytometers tend to have longer set-up and stopping time than other devices. Specific liquids circulate inside the machine in order to get it ready to count, or to clean it before stopping it. Automated cell counters, or manual counting with haemocytometer tend to be a wiser choice in case of sporadic and short cell counting sessions, due to the longer set-up time of flow cytometers. 8. Lab space or bench space The size of the device is a growing concern for users, given the cost of lab square meter. This cost is even higher for clean rooms. So the rental space should be taken into account and considered as a part of the ownership cost of the device Some flow cytometers can take up to 2 or 3 square meters from you lab, and should be taken into account.

5 9. Precision / Accuracy How close to reality are the measurements provided by the cell counting system. There is no way to know the real cell concentration of a sample. All systems introduce counting errors. Many technicians and scientific personnel ignore these errors, or assume that the measurement systems do not introduce errors at all. This is a risky approach. In some cases, the measured results do not have any validity given the error introduced by the device ( E.g. ERROR > 50% - 80% for low concentration samples ) It is wise to understand the types of error each device introduces for a methodical and diligent research. 10. Reproducibility Precise / Reproducible Reproducible Unprecise / Unreproducitble Flow cytometers are falsely believed to be very accurate. The truth, is that flow cytometers are very reproducible, but only when the sample is measure in the same moment in time (in this case, the Variation Coefficient = Std. Dev / Mean = 2-3%) However, if other measure is taken from the same sample a few hours later, results can differ from 10%-50%.