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A mathematical approach was developed and applied to raw data exported after the chromatographic course , in order ( i ) to normalise different 2D chromatograms , permitting their direct comparison and ( ii ) to automatically identify and calculate from pixel - to - pixel re - designed 2D chromatograms any differences among key volatile compounds .
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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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