21497
Volatilisation products of these organic substrates due to heterogeneous oxidation by OH have been determined at 1 atm using a high resolution proton transfer reaction time - of - flight mass spectrometer ( HR - PTR - ToF - MS ) .
 Chemical: OH
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