S14-0011, 1/2 Shipping Release

Record: 873

Category: Applications
Product: NH2P equilibration problem
Sample:

Question
Sorry for not replying soon.
I was off for the last few days, but after anther wash, it seems that when I elute sucrose in acetonitrile/water (75/25) and use acetonitrile/water (80/20) as mobile phase, I am now getting sucrose at 11.3 min. I do not know if this is ok or not, but it is an improvement. Actually, none of the two peaks appeared in figure 2 was sucrose based on MRM identification. Please, confirm that I understood what the tech suggested in his e-mail below. Adding 0.05% NH4OH/Acetonitrile (75/25). Does that mean, 0.05% NH4OH should be added to water and that should be 75% ; while pure acetonitrile is kept at 25%, or acetonitrile should always be 75%, and water + 0.05% NH4OH is kept at 25%.

Answer
I’m glad to hear your retention times are improving with the second washing procedure. It seems the washing procedure has regenerated your column.

The suggestion made by tech support was to use 75% of 0.05 ammonium hydroxide aqueous solution with 25% ACN. I think she suggested these conditions to improve the peak height and detection by LC/MS. However, if you are obtaining good results with ACN/H2O eluent please continue using those conditions.

Please let me know if you have further questions.

 
 
Additional Comments

Download or Print PDF