I have done AO assays on biscuits and I have the results and the moisture content. I used the following formula Cdry = Cwet (100)/(100 - %Moisture), which I found on another forum, but I wanted to check here if this was the correct way to adjust for MC? Thank you.
Dear Kim Blaides,
The MC is calculated as,
MC= 100* (W - Wdry) / Wdry.
where W is the weight at any point of time for which the moisture content has to be calculated and Wdry is weight after drying.
The equation which you have shown is same, just in another form. So, yes, MC can be adjusted using this method.
I hope these following links may help you.
http://www.environment.nsw.gov.au/resources/soils/testmethods/mc.pdf
http://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/5190/Moisture_Content_ocr.pdf
http://www.extension.uidaho.edu/forage/Proceedings/2004%20Proceedings%20pdf/Adjusting%20forage%20value%20for%20moistue.pdf
http://www.baycounty-mi.gov/Docs/CitizenCorps/CorrectingForMoistureContentOfFeeds.pdf
Hi Sabyasachi Swain,
Thank you for your help. I have used the eqn. you mention above to calculate my MC. I now want to use this MC to adjust my results for antioxidant analysis to correct for the MC.
So for example, I have a result of 19.11mg GAE per G of biscuit. The biscuit has a MC of 8.33%. So I used the above eqn as follows:
Cdry = 19.11 (100)/(100 - 8.33)
And got 20.2mg GAE per G dry weight. Would this be correct?
Dear Kim Blaides,
Its quite obvious that the dry weight of a will be lesser than that of wet weight. So, the above calculation (example problem) is not correct. I initially thought you have written correct equation in your question description. So I mentioned the formula that we used to follow for obtaining MC and said that its just another form. The equation that I have mentioned in my answer is correct. In your formula, there is an error of sign.
The formula should be, Cdry = Cwet (100)/(100 + %Moisture). The denominator should be 100+ %MC, you have mentioned 100 - %MC.
I am deriving the formula (in the form you have mentioned in description) from the equation I have mentioned in my 1st answer,
MC= 100* (W - Wdry) / Wdry
or, MC* Wdry = 100 W - 100 Wdry
or, MC* Wdry + 100 Wdry = 100 W
or, (100 + MC) Wdry = 100 W
or, Wdry = W (100) / (100 + MC).
This is the correct formula.
So, for the example above,
Cdry = 19.11 (100)/(100 + 8.33) = 17.64 units, which is quite possible.
I hope this helps.
All the best !
"The formula should be, Cdry = Cwet (100)/(100 + %Moisture)..... Cdry = 19.11 (100)/(100 + 8.33) = 17.64 units, which is quite possible."
I know I am late but this is not correct. An analyte will not become less concentrated when you dry the matrix (a biscuit in this case). If the matrix was 50% water, the analyte would double in concentration if the matrix were dried. So the original formula was correct... "Cdry = Cwet (100)/(100 - %Moisture)"
Or simply Cdry = Cwet/(1 - %water). This will correct for the %water in the matrix and adjust the wet concentration of the analyte to it's concentration as if it were in dry matrix.
Those interested at this discussion topic may find useful to check my post at: https://www.researchgate.net/post/How_to_express_total_phenolic_content_from_mg_g_wet_basis_to_mg_g_dry_basis2
There is a misplacement of variates in the above formula. It should be:
Cwet = Cdry(100)/(100 - %MC)
Cdry = Cwet(100)/(100 + %MC)
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