9114
We assessed OH production by quantifying the rate of formation of 3 , 4 - dihydroxybenzoic acid using a trapping agent , 4 - hydroxybenzoic acid , infused via the microdialysis probe , into the prefrontal cortex of rats exposed intraperitoneally to the solvents .
 Chemical: OH; Chemical: 3 , 4 - dihydroxybenzoic acid; Chemical: 4 - hydroxybenzoic acid
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: OH; Chemical: 3 , 4 - dihydroxybenzoic acid; Chemical: 4 - hydroxybenzoic acid