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Frequently Asked Questions (FAQs)

  1. Why is my serum turbid?
  2. How should my serum be stored?
  3. What is the stability of Valley Biomedical Serum?
  4. Is heat inactivation necessary to use the sera?
  5. What is the difference between Human Serum "Off-the-Clot" and Plasma Derived Serum?
  6. What is the difference between USDA Approved and U.S. Origin FBS?
  7. What alternatives does Valley Biomedical offer as lower cost options to FBS?
  8. What if I need a specially collected or processed material?
  9. Can I get a free sample?
  10. What if I have a problem?

1. Why is my serum turbid?

Serum turbidity is usually caused by the cryoprecipitation of lipid components during freezing and thawing the serum. The more times the serum is subjected to freeze/thaw cycles, the more turbidity is noticed. Shipping the serum frozen on dry ice at approx (-60) deg C and subsequently storing frozen at (-20) deg C is thermodynamically equivalent to a freeze thaw, even if the product is not allowed to liquefy.

Serum tubidity can be minimized by refraining from repeated freezing and thawing. If serum is not being used all at once, we suggest aliquotting into usable volumes, freezing at (-20) deg C and thawing the aliquots individually at the time of use.

For more information on serum turbidity, read our Technical Brochure - Turbidity of Serum.

2. How should my serum be stored?

Valley Biomedical suggests that serum should be stored frozen at (-20) deg C. If desired, the serum can be stored thawed in unopened containers at refrigeration (2 to 8 deg C) for up to two weeks. Once opened and exposed to microbial contamination, the serum should be used immediately and the balance of the material discarded, since microbial contamination can degrade the material rapidly.

3. What is the stability of Valley Biomedical Serum?

Based upon evaluation of the stability of "signal chemistries" (critical parameters of the sera from the biochemical profile) the product is stable for 24 months from date of manufacture when stored in unopened containers at temperatures of ( 20) deg C or below.

4. Is heat inactivation necessary to use the sera?

The typical purpose of heat inactivation is to eliminate protease and complement proteins which can be interfering substances when sera is used in certain cell culture systems. Usually, heat inactivation is not necessary, and may have some detrimental effect on the serum.

If deemed necessary, the typical heat inactivation protocol is to bring the temperature of the material to 56 deg C and hold it there for 30 minutes. Then cool the material to room temperature prior to use. Some precipitation may be evident, which can be removed if desired by filtration.

Heat inactivation is an optional service which can be performed by Valley Biomedical. Please inquire with Customer Service.

5. What is the difference between Human Serum "Off-the-Clot" and Plasma Derived Serum?

Off-the-Clot Serum is derived from spontaneously clotted whole blood. Plasma Derived Serum is obtained from plasma chemically treated to remove anticoagulant and fibrin. Although Off-the-Clot serum is desirable in certain specialized applications, Valley Biomedical Plasma Derived Serum will work for most cell culture applications and is more economical for the user.

6. What is the difference between USDA Approved and U.S. Origin FBS?

USDA Approved FBS is collected in countries which have been approved by the USDA for bovine serum importation into the United States. Typically, the material is quarantined, sampled, and tested by the USDA prior to release. Once approved by the USDA, the material is considered legal for sale and use. U.S. Origin FBS comes from USDA licensed abbatoirs located entirely within the continental U.S.

7. What alternatives does Valley Biomedical offer as lower cost options to FBS?

Valley Biomedical offers a variety of animal sera suitable for use in cell culture. Adult Bovine, Calf Bovine and Newborn Bovine Sera are available options.

In addition, we offer a low-cost FBS based product called FetalPlus. This all serum FBS substitute has very similar biochemical profile characteristics and cell growth promotion desired by researchers using traditional FBS.

8. What if I need a specially collected or processed material?

Since Valley Biomedical is a manufacturer selling directly to you, we can accommodate specialized requests (for example, gender, age, specialized anticoagulant, smoker vs non smoker, etc.). Please inquire with Customer Service for price and availability.

9. Can I get a free sample?

Valley Biomedical offers free samples of material and we encourage evaluation of lot specific samples. Our policy is that we will hold backup material for a minimum of 14 days during the evaluation process. Please contact Customer Service for specific details on obtaining samples for evaluation.

10. What if I have a problem?

Being a manufacturer selling direct to you, we have almost twenty years experience with the handling and use of sera. We pride ourselves in providing rapid response and support to the customer through our Technical Support Group.

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Valley Biomedical
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