Weird signal from PDHID detector
Posted: Wed Feb 08, 2017 10:38 pm
Hi all,
I'm using Varian GC 3400 model with TCD and PDHID. Last year, the PDHID was not working any more. The picture of PDHID signal(below) shows how it had been changed during 3 times measurements. The first graph is for a normal working, but the signal got weaker and weaker. Then, it finally dropped to a noise level. While I'm doing this, the 'pink light' (ionization light) at the PDHID also got weaker, too. From these facts, I concluded that the detector lifespan was over.
Then, I purchased the same detector model (from VICI company) and replaced it. When I run my GC with pure oxygen gas, the signal from the software (Varian star) looked weird (next picture, top graph: TCD and bottom graph: PDHID).
Although I saw the 'pink light' at the new detector, the peak signal is around a few hundreds of uVolt which is much less than that of the normal working(a few volts). Worse thing is that it's a negative sign. I checked the polarity was already 'No' and also tried 'cold starter' which means initializing GC setup, but I couldn't see any difference. If someone has a similar experience, please share any tips with me. It will be a great help to me.
Thanks,
Taemin
I'm using Varian GC 3400 model with TCD and PDHID. Last year, the PDHID was not working any more. The picture of PDHID signal(below) shows how it had been changed during 3 times measurements. The first graph is for a normal working, but the signal got weaker and weaker. Then, it finally dropped to a noise level. While I'm doing this, the 'pink light' (ionization light) at the PDHID also got weaker, too. From these facts, I concluded that the detector lifespan was over.
Then, I purchased the same detector model (from VICI company) and replaced it. When I run my GC with pure oxygen gas, the signal from the software (Varian star) looked weird (next picture, top graph: TCD and bottom graph: PDHID).
Although I saw the 'pink light' at the new detector, the peak signal is around a few hundreds of uVolt which is much less than that of the normal working(a few volts). Worse thing is that it's a negative sign. I checked the polarity was already 'No' and also tried 'cold starter' which means initializing GC setup, but I couldn't see any difference. If someone has a similar experience, please share any tips with me. It will be a great help to me.
Thanks,
Taemin