Acidity measurement in molten sulphur

Good morning to all,
I am looking for instrumentation that will allow me to measure the acidity of molten sulphur online.
Molten sulphur flows through steam pipes jacketed at a tamperature of 135-140°C.
The acidity varies in the range of 0.001-0.1% w/w expressed as H2SO4.

Is there any pH meter that can work in this context?
Thank you
None that could be used in actual service. You'll need to consider the equilibrium constants of the various ionic species at those temperatures as free H2SO4 probably does not exist as a separate component.