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The reactivity of peptides with chemicals ( peptide reactivity ) has usually been monitored by chromatographic methods like HPLC or LC / MS , which are robust tools for monitoring common chemical reactions but are rather expensive and time consuming .
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Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
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