Photoionization detector

[Jaehwan Lee]

Now we have PID detector for portable type.
This lamp IP range is 9.5~11.7 ev.

My question is like this.
Methane and water's ionization potential is nearly 12.5 ev. Carbon dioxide is also nearly 14eV.
So we can't analyze methane, water and carbon dioxide with our PID?

I'm looking forward to hearing of you.
Thanks.

[rb6banjo]

Correct. PID is terrible for aliphatic hydrocarbons but fantastic for aromatic hydrocarbons (e.g., BTEX). The GC we have for CO2 purity analysis has a PID because of the BTEX part of the ISBT specification. I have also used it in flavor analysis. Things that have flavor, tend to have lots of conjugated double bonds. PID has helped me a few times over the years.

[Jaehwan Lee]

I really thanks for your warm reply for my questions.
Best regards.

[AICMM]

Jaehwan Lee,

I would be surprised if you actually have an 11.7 lamp. That is not the most common since it is relatively short lived due to solarization of the window. For that reason it is suggested to keep it off when not in use and run it at the lowest possible temperature. To avoid the issue of the window you have to go to a windowless discharge detector like the HID or AID.

In addition, won't do water or methane although it will sometimes respond to some strange components like dichloromethane.

To do CO2 or methane you can look to either a TCD, HID or FID with a methanizer. To do water you are down to either a TCD or an HID (have fun with that one!)

Best regards,

AICMM

[Jaehwan Lee]

Thanks for your comments for this.
It helped me to understand PID.^^