how to measure the concentration of oxygen in oxide nanomaterial

[yasir.ustb]

i have prepared CoFe2O4 nano particles. now i want to measure the oxygen content in prepared sample, as i have used the reducing agent, so their is good chance for oxygen vacancies. in short i want to measure how much my samples are oxygen deficient?
which experimental technique is best for this?
inductive coupled plasma emission spectroscopy?
or
X-ray photoelectron spectroscopy?