Chromatography Forum

Dear All,

I am trying to determine the partitioning coefficients between PDMS and water. I used PDMS fibers and loaded them with mix of halogenated hydrocarbons. I back-extracted few of them to determine the initial loadings. Rest (from the same batch), I spiked in different volumes of water. After different time points, i back-extracted them the same way i did to determine the initial concentrations. Then, i determined the partitioning by normalizing the depleted fibers to initial loadings. I just used area counts of ECD for different peaks (i.e., subtracted the areas of peaks resulted from the depleted fibers from the corresponding peak areas resulting from the fibers back-extracted for initial loadings). I make sure that I use only non-overloaded peaks (quasi-guassian peaks) areas for the subtractions.

Now, the thing is that my boss is saying that don't use peak areas but develop a calibration curve to determine the concentrations and to verify that I am under linear range of the detector. Do I really need to do so given the facts:
1. I am normalizing the areas against the initial loadings;
2. I am not using overloaded peaks and stay under the linear limit

I asked the same questions to boss but he did not reply and said i still need to do calibration curve. Can someone answer above questions, please?

Best,
Kaka

In reverse order:

2) not using overloaded peaks:
Column loading (which gives rise to peak shape) and detector saturation (which can also affect peak shape, but in a different way) are two different things.

1) using normalized areas:
You may be normalizing, but you have not demonstrated linarity. With the level of detail you have given here, I can not guess more here.

Do you have to:
And, I learned a long time ago -give the boss the data he wants. If you interpret the data differnently, that's fine because you both have the data to work with. And you may both learn something. One thing your boss always needs to know (hopefully not learn) is that you are always willing to give his/her idea a good try.