FAQ: Sterol Testing
What instrumentation is used for sterol analysis?
Our sterol analysis is by gas chromatography with flame ionization detection (GC-FID).
What does the method quantitate?
This method is used to quantitate cholesterol, brasicasterol, campesterol, stigmasterol, and beta sitosterol in addition to the sum of total plant sterols and stanols.
Will it work on my matrix?
Sterol analysis by GC-FID can be used for numerous food products, animal feeds, pet products, and dietary supplements.
How does it work?
First, the sample is saponifed and the unsaponified portion is extracted with toluene. Then, an appropriate aliquot is evaporated leaving only the sterol and stanol residue. The sample is diluted with dimethyl formamide and derivatized. Finally, gas chromatography is used to analyze the sample and it is measured using external standards normalized with an internal standard.
What is the limit of quantitation?
The limit of quantitation is 1.0mg/100g per component and total sterols.
Can I submit a pure sterol sample for testing?
Yes, we have a separate procedure for high-level materials. Saponification is skipped and the sample is sonicated in dimethyl formamide until fully dissolved. Necessary dilutions are performed with dimethyl formamide and the sample is ready to be derivatized and analyzed by gas chromatography.
Do I need to worry about my something in my sample interfering?
We use 5 α-cholestane as the internal standard. If samples have peaks interfering with this, results are calculated using external standards as long as the standard curve passes criteria without the internal standard correction. If any samples with similar chemical structure to sterols or fat-soluble carotenoids and vitamins lead to poor resolution then sterols may not be able to be quantitated.
If I need Cholesterol reported also do I have to request an additional test?
No, this analysis quantitates cholesterol, so no other test is necessary.
Do you test for free sterols?
No, currently do not test for free sterols.
Are there any other sterols you are able to test for?
By request, we can add an additional standard that will also determine other components such as campestanol and beta sitostanol.
Have any other questions about sterol testing? Contact us now to get them answered.
