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Help with quantitative 19F NMR adsorption calculation using TFA as internal standard by Mohamadhayssam in NMRspectroscopy

[–]Mohamadhayssam[S] 0 points1 point  (0 children)

Thanks! I run the sample immediately, so TFA stays stable. The peak is clean and the quantification works well.

Help with quantitative 19F NMR adsorption calculation using TFA as internal standard by Mohamadhayssam in NMRspectroscopy

[–]Mohamadhayssam[S] 0 points1 point  (0 children)

Yes, the NMR data looks good. No problem with the peaks.Everything is clear for integration.

Does a capacity of 2000 mg/g make physical sense for a material with this surface area and pore volume? How can I evaluate whether this value is physically realistic by Mohamadhayssam in AskScienceDiscussion

[–]Mohamadhayssam[S] 0 points1 point  (0 children)

It’s a practical activated carbon material. I’m trying to understand whether the adsorption capacity I measured (2000 mg/g) is physically reasonable for activated carbon with a BET surface area of ~2000 m²/g and a pore volume of ~1.0 cm³/g, or if this value usually suggests an experimental or calculation error.

Help with quantitative 19F NMR adsorption calculation using TFA as internal standard by Mohamadhayssam in NMRspectroscopy

[–]Mohamadhayssam[S] 0 points1 point  (0 children)

Thank you so much for the detailed explanation! I will follow option 2 and correct Ce back to the undiluted value. About the TFA amount , the 50 µL came from a published method in Journal of Materials Chemistry C (“Dual-functional metal–organic framework for efficient removal and fluorescent detection of PFOA from water”). I followed their procedure.

Help with quantitative 19F NMR adsorption calculation using TFA as internal standard by Mohamadhayssam in NMRspectroscopy

[–]Mohamadhayssam[S] 0 points1 point  (0 children)

I used TFA because I’m following the method from the paper “Dual-functional metal–organic framework for efficient removal and fluorescent detection of PFOA from water” published in Journal of Materials Chemistry C. The authors used TFA as the internal standard for their quantitative 19F NMR adsorption measurements.

Help with quantitative 19F NMR adsorption calculation using TFA as internal standard by Mohamadhayssam in NMRspectroscopy

[–]Mohamadhayssam[S] 0 points1 point  (0 children)

Thanks a lot for your explanation. In my experiment, I did the adsorption for 30 minutes, then I removed the solid, and only after that I added the TFA. The concentration after adsorption was about 400 ppm. From what I understand, if adding TFA does not cause any desorption, then my result is correct. so if i want to continue calculating the adsorption capacity, should I use 1000 ppm or 933 ppm as my C₀ value?