Dilute and measure
By now the Vitroids™ disc is solubilized and a single-cell suspension is ready for BactoBox® measurements. Proper vortexing of the 15 mL vials is critical for reliable results. It isn't trivial. It requires a suitable vortex mixer attachment and a proper hold of the vial.
When vortexing is done correctly, a strong vortex forms in the vial within a few seconds. Follow the recommendations in the green information box and avoid the common mistakes demonstrated in the below slow-motion video (✔ demonstrates correct. ✘ demonstrates incorrect).
Good vortexing technique
Choose a mixer platform that is compatible with your vial. Some platforms can accommodate multiple vial types and sizes.
Use a gentle grip on the vial cap while vortexing the tube. Start with a firm 3-finger hold on the cap and switch to a gentle press with one finger once the motion starts.
The left panel demonstrates proper vortexing technique: The cap is initially held with three fingers to start the motion, after which a single finger applies light downward pressure while allowing the tube to vortex freely.
The center panel demonstrates improper technique: The vial is held too tightly using a central grip. The liquid bounces slightly, but the vortex does not form.
The right panel demonstrates improper technique: A 50 mL vortex mixer attachment is used for the 15 mL tube. The vortex does not start even though the grip is correct.

Step by step
Create a table of the results
Note down your results in a table.
In this example, the concentration is 89 000 cells/mL out of 130 000 total/mL. The first number is the bacterial concentration; the latter is the total objects detected in the measurement. Bacterial concentration is reported as a subset of the total objects and therefore 41 000 objects were something other than bacterial cells. The concentration may differ between different Vitroids™ discs.
Q17
100
89 000
130 000
Full measurement cycle is used for samples with low bacterial concentration
Because the bacterial concentration is in the low end of the BactoBox® working range, the full measurement time is used.
Summary
You have now measured the cell concentration in the liquid derived from the solubilized Vitroid™ disc. In the next page, Summary, we will give an overview of the procedure and the obtained results.
Run your measurements in Access
In this tutorial we keep things simple and demonstrate BactoBox® as a stand-alone-device.
But a manual log like the above table belongs to last century. Manual logs may get lost and it is common to make typing mistakes when you transfer data to spreadsheets.
Access is a powerful tool to keep track of dilution factors, sample IDs and results. Data are stored on the device and can be exported easily as a csv file. See an example in Track growth curve.
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