17317
Fourier transform infrared ( FTIR ) and high performance chromatography - mass spectrometry / mass spectrometry ( HPLC - MS / MS ) using atmospheric pressure chemical ionisation ( APCI ) under both positive and negative ion modes were employed for this purpose .
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Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
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