Online HPLC analysis - Agilent 1200?

[annaand]

Hi LC-ers,
Does anybody here uses online HPLC analysis for monitoring reaction?
I'm not sure how to build one. We have Agilent 1200 in lab (rapid resolution, up to 600Ba).
Some details of the project:
In our lab we synthesize a pharmaceutic drug in 3 stages. So far the synthesis is done in batch mode. HPLC is used to monitor the level of impurities in each step. We use 3 different columns, 3 HPLC gradient methods, and 3 sets of mobile phases (2 each: A and B).
Now the idea is to make it all online and measure the level of impurities in each of 3 steps.
My Agilent 1200 has 2 thermostated column compartments (ready to load with 4 columns).
It has a separate switching valve (G1158A Agilent 1200 Series 2 Position/ 6 Port Valve) - this can be use for mobile phases.
But I don't know what should I do with autosampler? It should be connected online to the synthesis line through another valve, right? This part I cannot figure out. Please, any advice? I'll be very grateful.
Thanks,
Anna

[Gerhard Kratz]

Anna, I don`t know if it is possible to use your autosampler for online analysis. A fraction collector which can be used as autosampler would be helpful. But to make it easy and more practicable I would use a separate pump for the reaction solvent to flush constantly a sample loop. The sample loop can be part of the autosampler. Some models have that option. So, if your autosampler has such a switching valve with sample loop, mainly this option is for pre-column derivatization, than you can use your autosampler. hope that will help.

[tom jupille]

It would probably be easier to ignore the autosampler altogether. Get another six-port two-way valve to use as an injector, and a metering pump to recirculate liquid from your reactor through the loop on this valve. The major limitation is that you will have to use "filled loop" injection, but that shouldn't be a big deal in that kind of setup.

[mardexis]

Wow! What a fun project. I like Tom's idea of using the fixed loop injection valve for the three streams. Expanding on that there is still a lot to do. You might use a multichannel peristaltic pump to pump your 3 streams. You might use a six position selector valve like the Grace/Alltech 85593 to select 1 of 3 streams for the fixed loop injector. You would need another 6 position selector to send the sample to the appropriate column (I can't think of a way to use your 2 position valves on column selector) Then I think you might need two more 6 position selector to route the appropriate mobile phase to the pump (high pressure mix or low?) If you also get the Agilent ADC card which installs in the pump module you can have chemstation coordinate the appropriate timing of all of the valving.

Good luck!

[Alera]

Pretty cool idea, I wonder though if it would be possible to come up with a single HPLC method that would accomodate all three analyses. That way, at least you don't have to joggle your six mobile phases..If your chemistry is not top secret, I'm sure folks here can come up with some ideas. It would be also easier to track your impurities throughout the process.

[annaand]

Thank you all for your replies.
They are great. I am working now on one method to all 3 streams. Pressure may be an issue here. I figured that I can use a valve with a sample loop for injection.
Thanks a lot!

[mardexis]

If you can use one column and set of mobile phases it would be much better. Definitely the right approach.

If you want more pressure you might try one of the high pressure valco injectors.

[giacomo56]

Agilent offers solvent selection valves in front of each pump channel....upto 12 solvents, therefore lots of combinations...also they offer valves for switching (filling) sample loop....give them a call..I bet someone already has done this.....