Delvotest® Negative Control
Delvotest® · Milk control
The Delvotest® Negative Control monitors the performance of antibiotic residue test kits in dairy quality assurance programmes. A negative control should never test positive, so it confirms your test and technique are working correctly.
| Type | Negative control |
| Storage | 2–8 °C, away from light |
| Reconstitute with | 15 ml water |
| Pack size | 6 vials |
Benefits
- Checks your test kit: Monitors the performance of antibiotic residue tests.
- Catches false positives: Reveals contamination or handling problems.
- Freeze for later: Reconstituted control keeps for up to two months frozen.
Features
Storage
Keep Delvotest® Milk Controls in a cool, clean, stable environment (2–8 °C, away from light), unopened in the original packaging until you are ready to use them. Always prepare a whole vial at once; partial preparation is not advised. As the controls are lyophilised (freeze-dried) milk, preparing them is called reconstituting.
Freezing for future use
Reconstituted controls can be portioned into smaller volumes and frozen for up to two months. Use the smallest practical portions to avoid waste.
- Portion directly after reconstituting, into clean vials of a suitable size.
- Label each vial with the control type and species (e.g. 'Cow Negative'), batch number, today's date, the date two months from today, and the operator's name or ID.
- Pipette the required amount (e.g. 2 ml) into each vial, close tightly and freeze straight away at about -18 °C.
- On the day of use, thaw the vial in lukewarm water for about 5 minutes, mix thoroughly, then follow the preparation steps. Once thawed, use the same day (kept at 2–8 °C or on ice). Do not refreeze.
If the negative control tests positive
A negative control should never test positive. If it does, investigate:
- Contamination: the most common cause of a false positive. Ensure proper sterilisation and handling techniques.
- Storage issues: verify the control was stored at 2–8 °C, away from light.
- Reagent quality: make sure all reagents are in date and stored properly.
- Instrumentation: maintain your equipment and validate test performance periodically.
Once you've found the likely cause, repeat the test with fresh negative controls, validate your equipment and improve handling practices.
How it works
- 1Wash your hands and clean your workspace. Avoid strong detergents or disinfectants, which could interfere with the control.
- 2Tear off the aluminium seal.
- 3Remove the stopper carefully and place it upside down to avoid contamination.
- 4Add 15 ml (± 0.5 ml) of distilled or demineralised water with a clean pipette. The water must meet ISO 3696 Grade 3 or higher; avoid tap water or water of unknown purity.
- 5Replace the stopper and, holding it in place, gently invert the vial about twenty times until the solution is homogeneous, without foaming. Use a mechanical stirrer if needed.
- 6Let it equilibrate at room temperature for about 30 minutes.
- 7Remix gently before use by inverting about twenty times. Use the reconstituted control on the same day.
Applications
Technical Specification
| Type | Negative milk control |
|---|---|
| Storage | 2–8 °C, away from light, unopened until use |
| Reconstitution | 15 ml (± 0.5 ml) distilled or demineralised water |
| Pack size | 6 vials |
About Delvotest®
Delvotest® was launched in 1973 and has become the most widely used test for antibiotic residues in milk worldwide, valued for its reliability and low cost per test. Many countries use it as their reference test, several of Australia's largest dairy export markets use it to screen imported dairy products, and it is the official test used by the Chinese government.
The original test was developed to detect Sulphadiazine and Penicillin G in milk, and needed a nutrient tablet added before the milk. The tablet was later built into the agar, which is why SP NT stands for Sulphadiazine Penicillin No Tablet.
Delvotest® is a trademark of the dsm-firmenich group.
Exportable Data and Reports for Regulatory Compliance
See how A3 technology finds what ATP technology can’t
