Chromatography Forum

Hello, I am a novice in experience with Hplc, I have ecountered something that has me stumped. When I inject my sample no peaks are detected. However, if i switch the valve to the other flow, the injection is detected during the realtime. It seems like the flow lines are crossed somehow, but I never physically changed anything. Has anyone had any experience with something like this before. Thanks

My system is:

Shimadzu

2 LC 20-AD pumps

Sil- 20 HT Autosampler

Spd-20A Detector

I run isocratic flow with one pump.

What do you mean when you say "switch the valve to the other flow?"

With a 2 pump Shimadzu, you probably have 4 lines that feed the two pumps. Make sure that the proper line is selected for the proper pump (or toss all 4 lines into your mobile phase bottle...)

-try to check your LC realtime in PUMP category maybe you used the other pump
-try also to check each line from the mobile phase reservoir to your pump.
- try to use gradient flow and test each individual line.

What is the backpressure before and after you've switched "the valve to the other flow"?

Best Regards