As you've not supplied details of which instrument you're working with, I'm going to have to be somewhat broad with my answer, so apologies in advance if I don't quite get there on the first attempt...
If you have a dedicated APCI probe (depending on the age and type of instrument, this may or may not be an IonSabre probe) then you will always be able to adjust the APCI probe temperature via the tune page as in the screen shot below.
You can also set the APCI probe temp in the MS Method Editor as seen below:
I'm not sure exactly what you're referring to as the "stock" set-up, however, if this is the ESCi option that you're referring to which can perform both electrospray and APCI then it works in a slightly different way. With the ESCi source, you are essentially using the standard electrospray probe and switching between using the capillary voltage to perform electrospray and the corona discharge to perform APCI.
As the standard electrospray probe doesn't have a dedicated probe heater (the dedicated APCI probes including the IonSabre probes do have a dedicated probe heater) all of the thermal energy to vaporise the eluent is provided by the standard desolvation heater, this is why there is no "APCI probe temp (°C)" setting on the ESCi tune page and you should just use the desolvation temperature as in the screen shot below to control the temperature for ESCi ionisation.
Hopefully this has gone some way to answering your question, please don't hesitate to ask if there's anything I've missed.
Thanks and all the best,Ed
Thanks Ed, I think that you have answered my question. Sorry about not being more detailed. We have an Acquity TQD. At the moment we have installed what I am calling the "stock" setup which is a "multifunction" probe (ESCi & APCI). It is not a dedicated APCI probe. We also have an IonSaber APCI probe that is not installed. I have been trying unsuccessfuly try to change the temperature and it occured to me that maybe that was only possible with a dedicated APCI probe.
No problem at all!
As you have the TQD, the standard set-up is the ESCI probe (multifunction ESI/APCI) but to use that in APCI mode, you have to use the ESCi tune page, it will not work with the APCI tune page (you need to have the APCI probe actually installed on the instrument for the APCI tune page to work...)
So, the temperature that you would need to use with the ESCi probe in APCI mose is the Desolvation temperature on the ESCi tune page.
As I said, any more questions, do please feel free to ask.
Thanks again. I believe my software version is different but I think I've got the general idea on what I will need to do.