IPA: /ˌreɪdiəʊˈkɛmɪkli/
KK: /reɪdiˈoʊkɛmɪkli/
In a way that relates to the study of the chemical effects of radiation and radioactive substances.
The samples were analyzed radiochemically to determine their isotopic composition.
Radiochemically → It is formed from "radio-" (from Latin *radius*, meaning ray) and "chemical" (from Greek *khemia*, meaning the art of transmuting metals) combined with the suffix "-ly" (meaning in a manner). The word refers to something that is related to or occurs in a manner involving rays and chemical processes.
Think of 'rays' ('radio-') interacting with 'chemical' processes, and remember that 'radiochemically' describes how these rays affect chemical reactions.