Chromatography Forum

Hi, colleagues!
Maybe it's a simple question, but I want to understand. During sample preparation, I use hydrochloric acid / water / methanol = 2/1/1. Heated and then evaporated to dryness, then concentrated in methanol.
But anyway I get residues of hydrochloric acid in the sample extract and acid enough. This is normal when working with column С18? Can be residues hydrochloric acid bad for ionization chamber or for column?

Please explain to me! Thank you!

With best regards!
Dmitry

With HCl in your extract you will be relying on the mobile phase to buffer the pH. Is your mobile phase capable of that? The answer will depend on the mobile phase at injection (i.e. its buffering capacity), the amount of HCl in the extract and the volume of extract injected.

With HCl in your extract you will be relying on the mobile phase to buffer the pH. Is your mobile phase capable of that? The answer will depend on the mobile phase at injection (i.e. its buffering capacity), the amount of HCl in the extract and the volume of extract injected.

Thank you for your reply Steve!
The mobile phase consists in a mixture of aqueous 0.2% (v/v) formic acid (solvent A) and methanol/acetonitrile (1:1, v/v as solvent B). I will apply the gradient. Gradually raising the percentage of eluent from 15 and up to 100 during the analysis. This is QQQ system with ESI, i think volume injection about 5-10 ul.

Amount of HCL in extract about. In the course of work, I use 37% acid, and the first step is diluted with twice. Therefore the order of 18%. After the evaporation step, remains about 10 ul. This amount was dissolved in 200 ul methanol / water. Therefore% acid in the final extract is about 1%.

With best regards!
Dmitry

If your flow rate is on the order of 1 mL/min you should be fine for pH.

If your flow rate is on the order of 1 mL/min you should be fine for pH.

Steve, thank you, for your reply!

With best regards!
Dmitry