@ Nick Gammon:
Thank you for the info on your website.
The temperature change of my system is like this: room temp to 100 deg C and back down to room temp in under 500 ms... as you can see I really need to capture and send this data.
@ bperrybap:
I did what you suggested in other way around: readings in ISR and sending in the loop. I will definitely experiment with your suggestion.
Thank you