Metabolomics Profiles of Smokers from Two Ethnic Groups with Differing Lung Cancer Risk.

52 Feature detection parameters include 5 ppm mass tolerance, minimum peak width of 10 s, and maximum peak width of 60 s; obiwarp was used for retention time correction with profStep set to 1, mzwid of 0.015, minfrac of 0.5, bw of 5, allowable retention time deviation of 20 s; unpaired parametric t test (Welch t test) and posthoc analysis for statistical analysis with a p -value threshold of 0.001 for highly significant features, fold change >1.5; adducts considered for the database search include [M + H] + , [M + Na] + , [M + H + Na] 2+ , [M + NH 3 + H] + , [M – NH 3 + H] + , and [M + H – H 2 O] + for ESI (+) mass spectral data and [M - H] − , [M + Na–2H] − and [M – H 2 O] − for ESI (−) mass spectral data.

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