The analytical methodology of isomers quantification has been studied and published in former study (Wang et al., 2013). From Figure1 in Supporting Information, it seems that the isomers were not separated, but actually it does not affect the quantification of the isomers. Because the main quantitative ions were used for quantification and the main quantitative ion of each isomer were separated absolutely (Figure 1). Table 1 and Figure 1 were cited from Wang et al (2013). Moreover, series of research about the NP isomers were conducted and published afterwards. The following are the publications.
The more critical issue lies in the analytical methodology used for isomers quantification. First of all, figure one is a chromatogram, not a spectrum. The chromatogram is not well resolved, i.e., there is no separation among the different analytes determined. For example, look at peaks 4, 5, and 6. There is no resolution among the isomers, the same for NP 7 and 8 and NP 8 and 10; thus, it is impossible to quantify them. If correct quantification is not assessed, then figure 1 and table 1 and 2 are not valid.