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Chemistry Forums for Students => Analytical Chemistry Forum => Topic started by: mehc on November 24, 2010, 05:08:32 AM

Title: GC quantification into mg/g
Post by: mehc on November 24, 2010, 05:08:32 AM

Facing some confusion in GC quantification.

Suppose we prepare a plant extract and analyze it by GC for some analytes.

Use of standard (in GC method) gives concentration of one analyte in mg/ml. How can we convert it in mg/g of plant material.

Definitely, we will use weights of material used and extracted in the course of  method, but i am searching for exact equation.

Really need some help in this regard.

Thanks

Title: Re: GC quantification into mg/g
Post by: Stepan on November 24, 2010, 02:20:11 PM

W(mg/g)=C(mg/mL)*V(mL)/Mplant(g)
W- analyte content in plant
C-concentration in extract
V-extract volume
Mplant- Mass of plant taken for extraction.

Title: Re: GC quantification into mg/g
Post by: mehc on November 25, 2010, 10:57:18 AM

Quote from: Stepan on November 24, 2010, 02:20:11 PM

W(mg/g)=C(mg/mL)*V(mL)/Mplant(g)
W- analyte content in plant
C-concentration in extract
V-extract volume
Mplant- Mass of plant taken for extraction.

Thanks a lot,
In my opinion, this equation is more suited for hplc quantification. In gc, concentration of sample injected should also taken into consideration. In one case, if we injected sample from 20 mg/ml, and in other case 30mg/ml, it will affect the quantification.

Title: Re: GC quantification into mg/g
Post by: Stepan on November 25, 2010, 11:25:04 AM

This very very basic formula  :-[ has nothing to do with analytical method you use. It assumes that you know how to measure concentration in your extract (C). How you do it - it is up to you.

PS. I did not get your example with 20 and 30 mg/ml and how GC is different from LC, sorry