Bio-Rad TC20™ Automated Cell Counter - Manual (Page 18)

Fig. 9. Loading the counting slide.
12
Performing Cell Counts
Performing Cell Counts
Loading Slides
Handle the TC20 ™ counting slides using the
edges and avoid touching the optical surface of
the slides.
Important: When loading the sample, place
the pipet tip at a 45° angle at the bottom of the
sample loading area (half circle at outer end of
the chambers). Slide the tip along the surface
and carefully touch the apex of the half circle
(Figure 9). Once the tip is stopped, depress the
plunger to begin the capillary loading process.
Care should be taken to avoid visible bubble
formation or back splatter. Do not overfill or
underfill the chamber. Overfilling the chamber and possible resulting accidental
spillage of sample inside the instrument could lead to biological contamination of the
cell counter.
The cell counting slides cannot be reused. Dispose of used slides as biohazardous waste
according to your local environmental health and safety regulations. To avoid injury do not
break the counting slides.
Preparing Samples
Preparing Samples without Trypan Blue Dye
1. Pipet 10 μl of the cell suspension into the outer opening of either chamber of the
counting slide (Figure 9).
Preparing Samples with Trypan Blue
1. To determine cell viability, mix 1 part trypan blue dye and 1 part cell suspension: In
a micro test tube or on Parafilm combine 10 μl of the cell suspension with 10 μl of
trypan blue dye. Gently pipet up and down ten times to mix.
2. Pipet 10 μl of the mixture into the opening of either chamber on the counting slide.
3. When counting the sample in duplicate, combine 20 μl of the cell suspension with
20 μl of trypan blue dye, and then pipet 10 μl of the mixture into each chamber.
Important: The cell suspension must be loaded into the counting slides and counted
immediately (within 5 minutes of mixing with trypan blue dye). Viable cells that are
exposed to trypan blue dye for an extended period may start incorporating the dye,
affecting the accuracy of the cell count.
Make sure the stock cell suspension is thoroughly mixed by pipetting or vortexing.
Failure to do so can result in improper sample representation within the loaded
counting chamber. Pipet the sample from the middle of the tube filled with stock cell
suspension. Pipetting from the bottom or top can result in a sample with a higher or
lower concentration, respectively.
If you work with adherent cells, use trypsin to get them into suspension. Using trypsin
instead of scraping improves cell roundness and decreases the number of cell clusters.