18750
Further experiments studying the reaction of mixed monolayers composed of unsaturated lipid POPC and saturated lipid dipalmitoyl - sn - glycero - 3 - phosphocholine , DPPC , revealed that no loss of DPPC from the air - water interface occurs , eliminating the possibility that a reactive species such as an OH radical is formed and is able to attack nearby lipid chains .
 Chemical: POPC; Chemical: dipalmitoyl - sn - glycero - 3 - phosphocholine; Chemical: DPPC; Chemical: DPPC; 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: POPC; Chemical: dipalmitoyl - sn - glycero - 3 - phosphocholine; Chemical: DPPC; Chemical: DPPC; Chemical: OH