"Chemical composition" refers to the specific types and amounts of elements that make up a substance or material. It describes what elements are present in the substance and the ratio at which they exist. Full definition
Other dogs have a certain chemical composition of their saliva, and they develop dental issues. (fidoseofreality.com)
People trying to avoid using marijuana often turn to the synthetic version, which is «dangerous and unpredictable,» said the speaker, because of the constantly changing chemical composition. (dnainfo.com)
She's also testing different chemical compositions for the mold itself. (sciencedaily.com)