Currently, I am wondering if there is any problem if I increase the percentage of modifier in the composition of modifier:CO2. I usually see that researchers would choose a 10 or 15% (v/v) when it comes to the composition.
Is there any maximum amount of modifier (v/v) can be used or do researchers just try to make it as low as possible?
Thank you for your time
The upper concentration limit for the modifier is determined by the phase behavior of the mixture. With too high of modifier concentration you will no longer be in the supercritical phase, thereby, losing many of the advantages that supercritical fluids possess. For the most common CO2 modifiers you can look up phase behavior easily on Google Scholar or another search engine for the conditions that yo are operating at including modifier concentration.
Are you running a commercially available SFC system, such as Agilent, Waters, or Teledyne ISCO?
Those systems generally have back pressure and temperature ranges that maintain supercritical conditions over a wide solvent range. We have an Agilent 1260 analytical and Teledyne ISCO ACCQPrep SFC. The Agilent goes up to 50% cosolvent, while the Teledyne ISCO system can run up to 70% cosolvent for supercritical elution.
While the Agilent allows 100% cosolvent in a gradient method, information in the operating procedures indicate 50% cosolvent is the maximum for supercritical chromatography. The Teledyne ISCO system limits the cosolvent to that known to be supercritical.
Please note that I am employed by Teledyne ISCO
https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.1001.8733&rep=rep1&type=pdf
https://thescipub.com/pdf/ajbbsp.2008.345.353.pdf
https://doi.org/10.1007/BF02933484
https://pubmed.ncbi.nlm.nih.gov/10836744/
https://doi.org/10.1021/ac00078a024
Dear Huỳnh Trí . See the following useful RG link: Article Influence of Modifiers on Supercritical Fluid Chromatography...
Kindly see also the following useful links : https://fahmylab.yale.edu/sites/default/files/files/Publications/prior2002/Fahmy_1993.pdf
https://academic.oup.com/chromsci/article-pdf/35/10/467/906952/35-10-467.pdf
Also check please the following useful link: http://www.aidic.it/eff2017/program/47lima.pdf
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