This website can be helpful: http://www.intertek.com/chemicals/carbon-nanotube-analysis/

Hello Miguel L. San Gregorio ,

Yes, we have had many issues relating to the quality of CNTs. Determining the quality is a very subjective thing though, I would imagine it is determined by the end application.

We even have issues when the manufacturer changes its protocol, but labels the product with the same identifier. The difference in performance for us has been an order of magnitude.

For our lab, we use CNTs to fabricate bioelectrodes and electrochemical capacitors. We often use defect sites to attach other functionalities and/or immobilise enzymes. Furthermore, for some applications we use them simply as fillers to form composites with other materials. For us, the quality very much comes down to:

available defect sites for modification

electrochemical activity (when using as an electrode within electrolyte)

conductivity (when used as a filler)

Thank you Md. Aminul Islam

Thank you Jules Lloyd Hammond for your reply, very insighful. After receiving some quotes from manufacturers, I found out that the cost of MWCNTs is considerably higher than that of SWCNTs, apparently, due to the complexity of the fabrication process.

I found an article explaining the fabrication of SWCNTs. Please find it bellow (from page 23):

https://www.sigmaaldrich.com/content/dam/sigma-aldrich/docs/Aldrich/Brochure/al_material_matters_v4n1.pdf?utm_source=redirect&utm_medium=promotional&utm_campaign=insite_al_material_matters_v4n1

However, I didn't find information about the fabrication process of MWCNTs, do you have any bibliography about it? I am trying to understand why they are easier to produce than SWCNTs.

Thank you!