Chromatography Forum

Hello,

n00b of a first post, however:
With the Empower 1 and the delay for next injection setting, does the flow of the method continue?

I want to determine the stability of an analyte in a solution (it is going off rather quick) and want to determine which is the best diluent to use. However I need to validate the method and thus have a documented time frame of events. I would love for the process to be automated where I can tell Empower/waters to inject eg, 20mins, 60mins, 300mins etc after the previous injection. However, is this even possible? I don't want to waste bucket loads of mobile phase while it equilibrates between injections.

Thanks in advance!

What you want to do:

Create a low flow method that you can run between your analysis, basically an isocratic method using you starting conditions at a lower flow.

Program the run samples page something like this.

Analysis method,Inject Samples, Run time 10.0 min
Low flow Method, Equilibrate, Run time 30 min
Analysis method, Equilibrate, Run time 5.0 min
Analysis method,Inject Samples, Run time 10 min
Low flow Method, Equilibrate, Run time 60 min
Analysis method, Equilibrate, Run time 5.0 min
Analysis method,Inject Samples, Run time 10 min
Low flow Method, Equilibrate, Run time 120 min
Analysis method, Equilibrate, Run time 5.0 min
Analysis method,Inject Samples, Run time 10.0 min

In this example, would you would have time points at 0, 30, 60, and 120 minutes while conserving solvent between injections.

Hi AA,

thank you for the replay - I figured this is what I might have to do.

Not knowing the stability at all it would be good to run for a total of 48hrs.
So narrow time window for the earlier injections up to say 5 hours and then gradually increase the time window between the time points. However, for the latter time points I can complete.
Although, I could try to be cunning and set up the run such that the different diluents are put on stability at different times so that while one is just ending the other starts (if that makes any sense!) However, I will have to work out if this is more effort!

My Run time is 22mins, blanks are desirable between samples to ensure no carry over - however, I can work this out.

For example a run like:
Analysis method; inject blank, 22mins
Analysis method; inject sample; T=0 22mins
Analysis method; inject blank, 22mins
Analysis method; inject sample; T=1, 44mins
Analysis method; inject blank, 22mins
Analysis method; inject sample; T=2, 66mins
Analysis method; inject blank, 22mins
Low flow method; equilibrate; 27mins
Analysis method; equilibrate, 5mins
Analysis method; inject sample; T=3, 120mins

ETC ETC Then I could start adding my other samples when the time windows get larger...I hope I got that all right.

Thank you for your help again!