To confirm: by "ROS", do you mean "reactive oxygen species"?
If so, I'm not aware of a current small molecule CyTOF-visible probe for it. Depending on the type of ROS, you might be able to use enzymes like superoxide dismutase or catalase levels as proxy for ROS levels.
In terms of overall oxygenation levels, the tellurium-based probes from Mark Nitz's lab at University of Toronto might also work: for example: https://www.ncbi.nlm.nih.gov/pubmed/27709819