> For the complete documentation index, see [llms.txt](https://help.sbtinstruments.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://help.sbtinstruments.com/mini-course/simple-measurement.md).

# Do a simple measurement

This mini-course shows you how to run a simple measurement. It uses an *E. coli* Vitroids™ disc as a sample. If in doubt, refer to the full tutorial, [Do a simple measurement](/tutorials/measure-vitroid-tm-disc.md). To measure a bacterial culture, see [Measure a dense culture](/mini-course/dense-culture.md).

<figure><img src="/files/aIqKy6N7RRK5MnRMcMTE" alt="A soluble E. coli Vitroids disc." width="188"><figcaption><p>Where you start: a soluble <em>E. coli</em> Vitroids™ disc. Where you end: a cell count on BactoBox®.</p></figcaption></figure>

***

{% stepper %}
{% step %}

### Get things ready

You need a BactoBox® setup with a flow cell, an *E. coli* Vitroids™ disc, a ready-to-use dilution vial, a disinfection vial, a P200 pipette, and a vortex mixer.
{% endstep %}

{% step %}

### Transfer the disc to diluent

Label a small vial, add 110 µL BactoBox® diluent, tap the Vitroids™ disc into it, and cap it tightly. Measure within 15 minutes.

<figure><img src="/files/ihVJ1ZoH1wSxO0fusU6m" alt=""><figcaption><p>Tap the Vitroids™ disc into the diluent.</p></figcaption></figure>
{% endstep %}

{% step %}

### Disaggregate the bacteria

Vortex 1 minute at maximum speed until the disc is fully dissolved with no visible clumps.

<figure><img src="/files/atWCCqLwixhvTrDmBQ48" alt=""><figcaption><p>One minute of vigorous vortexing gives a single-cell suspension.</p></figcaption></figure>
{% endstep %}

{% step %}

### Dilute 1:100

Transfer 101 µL of your sample into 10 mL diluent, suspend ×10 to rinse the tip, and vortex 10 seconds.

<figure><img src="/files/doitWovk1JoQL2ajeWLS" alt=""><figcaption><p>A single 1:100 dilution hits the working range.</p></figcaption></figure>
{% endstep %}

{% step %}

### Measure

Move the tubing kit to the 1:100 vial, press <kbd>Measure</kbd>, and wait for the result. Write down the *cells/mL* and *total/mL* before you start the next action.

<figure><img src="/files/aHMhf42uPfnaeswagtbo" alt=""><figcaption><p>Press Measure and wait for the two concentrations.</p></figcaption></figure>
{% endstep %}

{% step %}

### Clean

Move the tubing kit to the disinfection vial and press <kbd>Clean</kbd>. Always clean after a measurement.

<figure><img src="/files/9GehlWsFhoLh8RnW6gQh" alt=""><figcaption><p>Finish with a Clean.</p></figcaption></figure>
{% endstep %}
{% endstepper %}

Multiply the reading by the dilution factor to get the concentration of your undiluted suspension.

***

## Do it yourself

That is the whole loop. The full tutorial walks you through the disc, the diluent, and the calculation, step by step.

{% content-ref url="/pages/yOiWxVnPgOuX7cibH9R9" %}
[Do a simple measurement](/tutorials/measure-vitroid-tm-disc.md)
{% endcontent-ref %}


---

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