Chromatography Forum

Hi all,

My Shimadzu RID-10A is showing some periodic baseline drops recently. We just had a service call to change the lamp and the solenoid valve but the problem persists.

At first, I thought it might be the pump but the back pressure did not change through the occurrence. I notice the the lamp energy (new) drops, whenever the baseline drops
I purged the line everytime this happens, but it's practically no use. The problem occurs with or without the column, and it doesn't matter whether it's flowing through the sample or reference cell. Has anyone seen anything like this before? Could it be the photo-detector getting worn out?

http://www.tiikoni.com/tis/view/?id=502e324
http://www.tiikoni.com/tis/view/?id=991b5cd

Thank you so much for your time!! Thank you!

Best,

Jason

Cannot open the image.
What solvent are you using? Degasser in use?

Hello

It looks like there is air bubble somewhere - it could come from detector but also from other modules.
I'd suggest:
1.Flush detector with water (both cells), you can swap inlet with outlet - you can flush detector backwards.
You can also put tubing (waste line) with smaller diameter to have some back-pressure.
2.Stop LC pump or disconnect inlet to detector and watch baseline - with water in cell and zero flow you should see straight baseline. Of course you can see some drift because of temperature but definitely not huge signal increase like on photos.

Good luck

Regards

Tomasz Kubowicz

Cannot open the image.
What solvent are you using? Degasser in use?

Hi Gerhard,

I have updated the links, please see if you can visit them now. Thanks!

Best,

Jason

Hello

It looks like there is air bubble somewhere - it could come from detector but also from other modules.
I'd suggest:
1.Flush detector with water (both cells), you can swap inlet with outlet - you can flush detector backwards.
You can also put tubing (waste line) with smaller diameter to have some back-pressure.
2.Stop LC pump or disconnect inlet to detector and watch baseline - with water in cell and zero flow you should see straight baseline. Of course you can see some drift because of temperature but definitely not huge signal increase like on photos.

Good luck

Regards

Tomasz Kubowicz

Thanks Tomasz,

You may be right because the baseline stays flat when the pump is off. However, it doesn't explain why the lamp energy decreases when the pump is running. Any thought? Thank you for your time.

Best,

Jason

I'm wondering if this is tied to your lab's HVAC system.

I'm wondering if this is tied to your lab's HVAC system.

Hi Dr.

We don't have a HVAC system associated with our LC. Any other suggestions? I have already tired everything everyone suggested, still no luck. Thanks


Jason

You may try a different pump if any , it seems there is something coming out of the pump.