Chromatography Forum

Here's my dilemna. I have an agilent 1200, quat pump, degasser, all the bells & whistles for what I need. However, I am a newbie to this.

Here's my confusion:

Our method uses phosphate buffer and Acetonitrile for our sample runs. Sometimes I'd like to be able to set up a sequence so that samples can be run during after-work hours, and set up a post-run Standby command. However, I know it's not good to leave buffers in the system and column (salt issues).

What I want to do is set up a sequence that will:
-Run my samples using the Phosphate Buffer/ACN
-When sample runs are complete, tell the pump to switch solvents from Phosphate Buffer/ACN to Water/ACN (or just water, whatever is best)
-Instruct the pump to let the water run through the system and column until the column is flushed of the phosphate buffer
-put the system on Standby, so the whole machine shuts down for the night.

Anyone know how I can accomplish this? Agilent's "Help Menu" is very limited in explaining the commands you can program into the sequence. Or does anyone know of macros that can accomplish this? Where would I begin to look?

Or.... do I have to make that dreaded call to Agilent's Tech Support...??
(ugh)

Any advice, feedback, or instruction would be so greatly appreciated!

Thanks so much-
LabRatSar

Start with your current method. Make changes such as decreased pump flow (and lower pressure limit), and save as a different Method Name. On Sequence, Sequence Parameters, set in lower right hand corner the checkmark, and "lampall off" which will turn the lamps off but not the pump. Then in the Sequence Table enter this Method in as the last line; you can set blanl for vial number (no injection) but must enter a number (such as "1") into the injections per vial column. So after the one dummy run the pump continues to pump at those conditions until you change it back. So you can keep the same mobile phase running slower, or even change to your other reservoirs.

I use the sequence table to run my samples, flush the column with 50:50 water:organic, then turn the flow and lamp off.

For Over Weekend Run:
I have my 50:50 water:organic flush reservoir in Line D. I make a method with Line D called 'FLUSH' (or RINSE) to rinse at whatever flow rate I deem appropriate (usually 1 mL/min) and to last 30 - 60 minutes. Enter this method at the end of the sequence with 100µL injection volume of WFI to help rinse needle line, and no wavelength saved in the detector part. Then, I make a method called 'FlowOff' with pump set at 0 mL/min and lamp off, and put this after the FLUSH method in the sequence table.

For Over Night Run:
I do something similar to Consumer Products Guy's procedure, with a method called 'FlowDown."

I've tried the timed events and macros without success.

Hope this helps.

Hi all, if I may add my take here... I do this all the time, run my sequence with a "wash" method at the last line... the method is setup to pump the rinsing mobile phase with a 120 or 180 minutes stoptime, and with no UV signals or spectra (DAD) to be stored, and also uncheck the required lamp box in the detector configuration dialogue box, then everything shuts down and i come next morning to a washed and shutdown system. In addition to what SDallybeetle said, and instead of having to set a "no flow" method, you can enter the pre-run command "LAMPALL OFF" in the runtime checklist of the particular wash method, this way the method will start running and will automatically turn the UV lamp off and continue pumping at the specified FR for the specified stop time of the method... just make sure you check the post-run command/macro in the sequence parameters window to STANDBY or to PUMPALL OFF since you've already turned the lamp off at the beginning of the wash method. Also, in the runtime checklist make sure you check data acquisition or Chemstation will issue a "nRdy" signal to the sequence and will terminate the sequence altogether.

In addition to the above comments:

Since you have a quat pump, make sure one of the channels (A or B) has water with no buffer or other dissolved solids, since you need to use this channel for flushing out the buffers (but remember you should also clean out the buffer line occasionally).

All of the above options will work, but you could combine some of the steps into one method. For example, the "flush" method (last line in the sequence) could start with the same organic/water mixture, but without the buffer. This will minimize the chance of precipitation. After flushing about 10 column volumes, program a gradient (can be fast) to all organic, and pump for another 5 - 10 column volumes. This now should leave you with a cleaned stationary phase that can also be stored if needed.

In the Sequence Parameters, I choose "shutdown.mac" at the end, as this shuts down the whole system (pumps, lamp, heater, etc.). This is the best option for a weekend shutdown.

Also, you might explore using the ChemStation scheduler to start the system up on Monday morning, before you arrive. That would save equilibration time.