Common problems in the use of serum - Database & Sql Blog Articles
1. How to store and thaw serum without compromising product quality?
Once the serum is removed from the freezer, it should first be placed in a refrigerator at 2–8°C to begin the melting process. After it is fully thawed, it can then be brought to room temperature. It’s important to gently shake the serum during the thawing process to ensure even mixing and prevent uneven temperature distribution.
When stored at 2–8°C for extended periods, proteins and lipoproteins such as cold agglutinin, fibrinogen, and vitronectin may clump together, forming visible precipitates or cloudiness. To maintain stability, it's best to store serum below -20°C and avoid repeated freeze-thaw cycles. If you're not using the entire bottle at once, consider aseptically aliquoting it into sterile containers before refreezing.
2. What are the flocculent precipitates in the serum, and how should they be handled?
The precipitate typically consists of fibrin and lipoproteins, which are natural components of serum and do not affect its quality. To remove them, you can centrifuge the serum at 400g for 1–2 minutes, or let it settle and carefully transfer the supernatant to a new sterile vial. Filtration is generally not recommended, as it may clog the filter and fail to remove the particles effectively. In most cases, shaking the serum and warming it to 37°C will help dissolve the precipitate naturally. Therefore, it's advised to gently mix and warm the serum to 37°C before use.
3. How can precipitation in serum be prevented?
To minimize the formation of precipitates, follow these guidelines:
(1) During thawing, regularly shake the serum to ensure even temperature and composition, reducing the likelihood of sedimentation.
(2) When freezing serum, shake it occasionally (without creating bubbles) to maintain uniformity in temperature and content.
(3) Avoid direct thawing from -20°C to 37°C, as rapid temperature changes can cause protein denaturation and precipitation.
(4) Do not leave the serum at 37°C for extended periods, as this can lead to cloudiness and degradation of sensitive components, affecting overall quality.
(5) Heat inactivation of serum is often unnecessary, as it can increase the risk of precipitate formation.
(6) If heat inactivation is required, follow the standard protocol: 56°C for 30 minutes, while continuously shaking the serum. Excessive heat, prolonged time, or uneven shaking may increase the amount of precipitate.
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