Delvotest® Milk Controls are essential tools for ensuring the accuracy and consistency of antibiotic residue testing. Proper storage, preparation, and handling of these controls are critical to maintaining their integrity and reliability. In this article, we'll cover:

• How to store them before and after preparation

• Step-by-step guide for ensuring proper preparation and application

Storage Before Use

You'll need to keep your Delvotest® Milk Controls in a cool, clean and stable environment (2–8°C, away from light). We advise leaving them unopened in the original packaging until ready for use.

Preparing for Use

To ensure accurate results, it is essential to prepare an entire vial at once — we do not advise partial preparation. As Delvotest® Milk Controls are lyophilised, dry comingled milk, we usually refer to the process of preparing them as 'reconstituting'. To get your controls ready for use, just follow these steps:

1. Wash your hands thoroughly and clean your workspace. Avoid using strong detergents or disinfectants, as they could interfere with their performance.

2. Tear off the aluminium seal.

3. Carefully remove the 'stopper' from the bottle and place it upside down somewhere to avoid contamination.

4. Using a clean pipette, add 15 ml (± 0.5 ml) of distilled or demineralised water.

5. Put the 'stopper' back on.

6. Hold the 'stopper' in place and gently invert the vial c. twenty times to mix the contents thoroughly — avoiding creating foam, and ensuring the solution is homogeneous.

7. Allow the contents to equilibrate at room temperature for c. 30 minutes.

8. Remix gently before use, inverting the bottle c. twenty times.

[[Visual Example: [[ Insert image of a reconstituted vial here]] // actually, we should make a really short video you know? Simple stuff. — much easier to illustrate a process like this]]

Once reconstituted, your Delvotest® Milk Controls should be used on the same day. However, if you have any leftover solution, it is possible to portion and frozen it for another time.

Freezing for Future Use

Reconstituted Delvotest® Milk Controls can be portioned into smaller volumes and frozen for later use. Be sure to portion the controls into the smallest practical volumes depending on your use case for future use to avoid unnecessary waste. To prepare and store them properly, just follow these steps:

1. Gather clean vials of an appropriate size for portioning.

2. Label each vial with at least the following information:

   • Control type including species (e.g., 'Cow Positive Pen G 4ppb').

   • Batch number.

   • Today's date.

   • Two months from the current date, as reconstituted controls can be stored for up to two months in the freezer.

   • Operator's name / ID

Altogether, your vial's label notes should look something like this:

Cow Positive Pen G 4ppb

Batch: 2312457 [[- BETTER to add real batch number]]

Prepared on: 7 July 2024

Valid until: 7 September 2024

Prepared by: Jan Kees

3. After reconstituting the control, pipette the required amount (e.g., 2 ml) into the vials, close them tightly, and place them directly into a freezer at c. -18°C.

4. Follow the 'Preparing for Use' steps in the section above — keeping in mind that on the day of re-use, you'll need first to thaw the vial by placing it in lukewarm water for a short time (c. 5 mins), mixing the contents thoroughly before using.

Once thawed, the reconstituted controls can only be used on the same day if stored between 2–8°C (or on ice). Do not refreeze the controls after thawing.

Summary

Proper storage, handling, and preparation of Delvotest® Milk Controls are essential for ensuring the accuracy and reliability of your antibiotic residue testing process. By following the guidelines for reconstitution, same-day use, and freezing, you can maintain the integrity of your controls and ensure consistent results. Whether you're using them immediately or storing them for future tests, these milk controls are designed to provide dependable performance when handled correctly.