This is a very important point since it is a high temperature synthesis and formation and thereby contamination from organic fluorophore is a real concern (very few people actually take this into consideration). In order to ensure the formation of nanoparticle (NP) you can try DLS (though TEM is preferred due to small size). Presence of NP does not necessary mean absence of organic fluorophore. You can perform a dialysis with your sample to remove organic molecules. (Please confirm that the absorption and excitation spectra matches.)

Thank you Tuhin Khan..

I will suggest you to do Photolumincesnce characterization. I am attaching an article which have explained how to use PL spectra to differentiate between CQDs and other organic materials.

Thank you Chandra Bhal Sing for your valuable suggestion, i have gone through the article. The article is very informative and interesting. It clearly differentiated the carbon dots from other fluorescent materials like inorganic quantum dots based on their unique excitation dependent PL emission and the use of surface passivating agent for enhancing the PL. However, according to recent reports surface passivtion in not necessary to produce carbon dots with high Quantum yields and excitation independent emission is also most commonly observed (which is the actual reason for my confusion).

I request anyone expertise in this field to suggest me the possible ways to differentiate carbon dots from organic fluorescent molecules.