> 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/more/how-to-guides/basic-sample-preparation.md).

# Basic sample preparation

Accurate dilutions need a real vortex, the right vortex time, and a rinsed pipette tip.

BactoBox® measurements require dilution. Three habits make your dilutions accurate.

## Get a vortex when you vortex

When you vortex, you must get a vortex[^1]. The right grip on the tube makes that easier.

<figure><img src="https://4216107837-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FeYTtd7c0A325muFr5lMW%2Fuploads%2F7HRc2ei66MlVemMuHrUb%2Fvortex-right-trimmed.avif?alt=media&#x26;token=dbcc8c37-47e2-4ea2-add7-803302b82a07" alt=""><figcaption><p>Slow-motion vortexing of a 15 mL vial. Left: correct grip and correct attachment, and a vortex forms. Center: too tight a grip. Right: wrong mixer attachment. For the right grip, hold the cap with three fingers to start the motion, then switch to light pressure with one finger.</p></figcaption></figure>

## Vortex for the right time

* **Your culture, 30 seconds.** Cells in a culture tend to stick to each other, and 30 seconds disperses them before your first dilution.
* **Each diluent vial, 10 seconds.** Vortex right after you dispense into it, so the vial is evenly mixed before you take from it or measure it.

## Rinse the pipette tip

After dispensing into a vial, pipette up and down once or twice in that same vial.

**A 1:100 dilution transfers about 100 µL. Whatever stays behind in the tip is a significant share of that.**

<figure><img src="https://4216107837-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FeYTtd7c0A325muFr5lMW%2Fuploads%2FSOLJxncC2ta2DrgkKqTP%2Frinse-the-tip-v4-white-1600.jpg?alt=media&amp;token=6b473d3c-ffd3-43d2-9422-1bfdfb0b805d" alt="Rinse the pipette tip in three steps. 1, dispense: sample is left in the tip. 2, draw up: diluent rinses the tip. 3, dispense again: all sample is in the vial. Repeat steps 2 and 3 once or twice."><figcaption></figcaption></figure>

[^1]: A vortex is the tornado-shaped funnel that forms in the liquid when the vial spins fast enough. If the surface only trembles or bounces, there is no vortex.


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