7006
The presence of trace metal cadmium assay was investigated with a copper immobilized on a graphite carbon electrode ( GPC ) , the modified property of which was determined with handheld voltammetric systems .
 Chemical: cadmium; Chemical: copper; Chemical: graphite; Chemical: carbon
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
 Entities: cadmium, copper, graphite, carbon 
Answer:
 Chemical: cadmium; Chemical: copper; Chemical: graphite; Chemical: carbon