Could anyone help me to elucidate the concept between deactivated and endcapping of column?

Thanks

A silica gel based reverse phase has always some residual silanol groups. There are more ways to supress their activity. They can be partialy eliminated by endcapping procedures, or can be "covered" with some large hidrophobic side groups, etc. I would say, endcapping is just one way to deactivate a RP stationary phase.

Good luck

Endcapping is a real process. "Deactivated" is marketing and stands for "we claim that our stuff is better".

For endcapping, a smaller silane is used. Typically, a trimethylsilane is used for endcapping. It covers a larger amount of silanols than the larger silanes, but does not eliminate them due to steric limitations.

Very thanks!
I am now understand that endcapping is just one way to deactivate a RP stationary, so could you please tell me other ways to deactivate a PR stationary?

Thanks a lot!

To analyticalperson:

In general terms, the silica matrix is deactivated by: removing iron, aluminum, calcium, and sodium ions from the raw material of the matrix, and minimizing the creation of free and geminal silanols when the matrix is polymerized.

How specifically the column manufacturers achieve this is usually considered a trade secret by the manufacturer. But basically, more purifcation steps, and better quality control ultimately improves the HPLC results a column provides.

As people demanded less tailing of basic analytes, and less ion pair dependence for compatibility with LC-MS, it became cost-effective for the manufacturers to clean up this "sand in a tube" before they sold it to us.

Thanks!

can i use ion pair reagents in the mobile phase using for lcms? will it affect the ionisation of sample? pls explain

Classical ion-pair reagents are not used in MS (for example octyl sulfonic acid). They are likely to accumulate on the interface. TFA is often used with peptide applications. There have been some studies that demonstrated ion suppression with TFA.