Certificate of Analysis Lookup
Please locate the serial number (abbreviated as "s/n") on your product and use it to reference the table below:
Vitamin K2 MK-4 Powder
| Serial Number (s/n) | Date Range Sold | Date We Received Batch | Lab Results |
|---|---|---|---|
|
Axxxx |
Aug 8, 2024 - onward | June 28, 2024 |
|
*1 How did the COA result come back at 110%? Is this a joke?
We had the same question when we saw the COA. Looking at the comments section of the COA above the "SGS Sample ID" we have a blurb from the lab:
| "The certified standard QC preparation on this batch of samples recovered at 110%. With an RSD of 6%, this falls within 91 – 115% confidence interval with a method uncertainty of 95% confidence, coverage factor of k = 2" |
A simplified layman's translation of the comment and COA: When the lab we hired ran a sample of our vitamin k2 mk-4 and a certified reference sample of the same vitamin through the same instrument on the same day using the same technique and person, both samples produced a final result of 110%. This indicates that both samples have a high degree of similarity.
If you want to geek out with us on the nitty gritty details, we appreciate your diligence. Please keep reading!
Understanding how any result above 100% is possible, we also need to understand how the lab analyzes the purity of a given sample.
Lab instruments only produce reportable results when the results fall within the instrument's calibration curve. The calibration curve is a range of sample concentrations where the instrument has been determined to produce acceptable results (more on calibration curves, pdf).
For example, if the range of the instrument's calibration curve is from 0.1 to 20 ug/mL (micrograms per milliliter), then we would have to dilute our, potentially close to 100%, sample down into that range (preferably near the middle of the range).
If we wanted to dilute our sample down to 5 ug/mL, then we could take 0.05 g of our sample and mix it with 10,000 mL of solution. This creates a 5 ug/mL dilution:
0.05 g ÷ 10,000 mL = 50,000 ug ÷ 10,000 mL = 5 ug/mL
Practically speaking, we diluted our potentially 1:1 (100%) sample down into a 1:10,000 (0.01%) sample (a large dilution).
Continuing our example, let's say we ran this diluted preparation through the analyzing instrument and received a result of 5.5 ug/mL. We would have to "un-dilute" the results in order to get back to our initial baseline and desired unit of measurement. To "un-dilute" the results we take the result multiplied by the dilution ratio of 10,000 divided by our initial input of 0.05 g:
5.5 ug/mL · 10,000 ml ÷ 0.05 g = 1,100,000 ug/g
Since there are 1,000,000 micrograms (ug) per gram (g), 1,100,000 ug/g equates to 110%:
1,100,000 ug/g ÷ 1,00,000 ug/g · 100% = 110%
Now, you might be clamoring that this elaborate explanation still doesn't explain how or why the instrument would output an above 100% reading. And you're right.
A realization we had is that any laboratory measurement has uncertainty built-in, hence the method uncertainty and confidence interval. While balances are calibrated daily with standard weights, volumetric glassware markings are standardized, and pipettes are checked and documented, there are inherent discrepancies, however minuscule, introduced via human interaction, the lab environment, instrument calibration, etc. especially when dilution (use of a pipette) is required.
Because of these inherent discrepancies labs will provide a method uncertainty in the form of a confidence interval. In essence, based upon the previous analyzations done on certified standard samples we have the following historical recovery data (mean recovery is inferred from provided data):
- Relative Standard Deviation (RSD): 6%
- 95% Confidence Interval Range (95% CI): 91 - 115%
- Mean Recovery: 103%
- Mean Recovery is calculated by taking the minimum 95% CI + 2RSD = 91% + 2 · 6% = 103%
The above data shows that 95% of the time the lab analyzes a 99.9% ±0.1% certified standard sample of vitamin k2 mk-4, the recovery result will fall between 91 - 115%.
In our opinion, the main takeaway is: as long as our sample recovers at a similar percentage to the 99.9% ±0.1% certified standard sample on a calibrated instrument and both tests were run on the same day, by the same person using the same instrument and technique (which is what we're told happened), then we can be reasonably confident that the 2 samples are highly similar.
We hope this is a sufficient explanation of how the results could turn out this way. If you think otherwise, please send us a message!