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. Author manuscript; available in PMC: 2017 Aug 5.
Published in final edited form as: Anal Chem. 2016 Aug 8;88(17):8802–8811. doi: 10.1021/acs.analchem.6b02222

Figure 4.

Figure 4

(A1–A3). Identification of citric acid and iso-citric acid by ADAP-GC 3.0 at the lowest concentration 0.2 μg/mL among the seven data files in Sample I. Citric acid and iso-citric acid share many peak features (A1) and only the simple peak feature of m/z 245 was qualified as the model peak for iso-citric acid (A3). The mass spectrum for citric acid was directly extracted at 19.81 min since the first round of clustering indicated that there was a compound around 19.81 min (A2). (B1–B3) Identification of citric acid and iso-citric acid by ADAP-GC 3.0 at concentration 0.4 μg/mL. Many peaks features were shared (B1). The first round of clustering indicated that there were at least two compounds within the deconvolution window (B2). Model peaks were found for both citric acid and iso-citric acid with m/z 183 for citric acid and m/z 245 for iso-citric acid (B3). (C1–C3). Identification of histidine by ADAP-GC 3.0 at concentration 0.4 μg/mL. Peak features of histidine were at much lower intensity values than the co-eluting lysine (C1) and only the simple peak feature for m/z 174 was selected as the model peak for lysine (C3). The mass spectrum for histidine was directly extracted at 21.91 min since the first round of clustering indicated that there was a compound at around 21.91 min.