DS Description
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The obtained data matrix (observations: sa … The obtained data matrix (observations: samples, variables: 337 peaks, including peaks with mass spectral tags [137 annotated peaks from GC-TOF/MS plus 200 annotated or stably appearing peaks from CE-TOF/MS analysis; Supplemental Tables S4 and S5]) was used for statistical analysis. For statistical multivariate analysis, principal component analysis was performed with SIMCA-P 11.0 software, using log10-transformed and autoscaled data (Umetrics AB). Simple comparisons of means of obtained peak areas were performed by Welch's t test. A difference of P < 0.05 was considered to be significant. In terms of minimizing the effect of zero substitution, we scaled all normalized peak areas by 10,000 and then added 1 uniformly. reas by 10,000 and then added 1 uniformly.
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