Re-equilibration steps in sequence window

[StevenS]

Autosamplers working with the Clarity sequence window are designed to automate the running of LC and GC so you don't need to come back until everything is finished (albeit it helps occasionally to check that nothing has gone wrong). I've come up with an idea to make this better.

It concerns re-equilibration. Suppose you have two methods which run on the same column but they have different eluents that are both ready to go on a gradient pump. In the morning you run method 1 and in the afternoon you run method 2. Between finishing all your runs on method 1 and starting method 2, you have to equilibrate to the new eluent used for method 2. To automate equilibration in Clarity you can use 'Idle Time', found by going to 'sequence->options...'. The problem with this is that it puts an idle time before every run. If you only want one idle time to appear on the change of your method, this can't be done.

I propose that a new feature is put into the sequence window. Instead of using the 'idle time' function, we should be able to put in a step (a row) that doesn't have a vial number but serves as an equilibration step, with the new method in the method column. For example:

Code: Select all

     SV   EV  .............. Method Name    Equilibration time
    --- ----                -------------  ----------------------

5    5     5                     Method 1             ---
6   --    --                     Method 2             30
7    6     6                     Method 2             ---
.    .     .                           .               .
.    .     .                           .               .
.    .     .                           .               .

What do we all think about this?

Steven Saville.

[Ivan Vins]

Dear Steven,

for this purpose I will suggest to create a specific method and run it in the Sequence between the two series of samples to equilibrate the system for the changed conditions. You could use the Bypass sample type to perform the run without actually injecting a sample. (On samplers not supporting this feature, use just injection of the solvent or blank).

The same approach by using a dedicated method could be used to shutdown the system after the sequence is finished

Please let us know, if this is a viable solution

[StevenS]

Hello Ivan,

On comparing your suggestion with mine I can see that both have their pros and cons:

My idea means you don't have to make an intermediate method and you can choose how long you want the equilibration time to be in the sequence window. It would just run the initial conditions only for the equilibration time you set on the new method you want to equilibrate for.

However, my idea wouldn't suit if you have two methods that use very different eluent compositions. For example, suppose method 1 is 10% MeCN and 90% water and buffer; suppose method 2 is 100% MeCN. In order to protect the column, you really need to flush out the buffer first before putting through pure MeCN, otherwise buffer could precipitate out and block the column. So in that scenario, it would be better to use your idea of an intermediate method, probably a gradient which flushes out the buffer and then ramps up the composition to 100% MeCN.

Suppose we have a different scenario: Method 1 is 25% MeCN, 75% water and buffer and Method 2 is 60% MeCN, 40% water and buffer. In this scenario you wouldn't need an intermediate step, just switch over from method 1 to 2 and equilibrate. In this scenario their are currently two ways I can see around it, plus my idea. You can run a blank or bypass (if supported) of method 2 in order to equilibrate to method 2. However, if your method run time is different from the time you want it to equilibrate for, you either have to do more than one run to equilibrate it. Or you can set up an intermediate method, as you suggested, with a run time equal to the time you want to equilibrate for. This is why I think my idea of having an equilibration time would be an elegant solution (if not a perfect one in all cases as explained above).

Either way, it is only a suggestion . I understand if there are plenty more bugs which need to be solved before something like this is considered!