## 3 Results and Discussion
In the cases of the ESI and MALDI methods (the middle and bottom mass spectra of Frame 3a, respectively), a stable  
Figure 1: (**a**) basic structure of primary (1\({}^{\circ}\)), secondary (2\({}^{\circ}\)), and tertiary (3\({}^{\circ}\)) amines; and (**b**) chemical structures of phenethylamine, tryptamine and their derivatives of various substituents. protonated parent ion ([M+H]\({}^{+}\), \(m/z=256\)) can be clearly observed. The \(\alpha\)-cleavage process would produce a major fragment at \(m/z=239\), indicating the loss of a neutral fragment, \(256\,-\,239\) = 17 (NH\({}_{3}\)). In the \(\beta\)-cleavage process, a peak at \(m/z=30\) (H\({}_{2}\)C=N\({}^{+}\)H\({}_{2}\)) should be observed, indicating the loss of a larger neutral fragment, \(256\,-\,30\) = 226. However, the peak of \(m/z=30\) cannot be seen on the ESI-spectrum because the detection range of the instrument (Finnigan LCQ Classic) is limited to \(m/z\) above 50. Our group used the MALDI method to examine this and found that the fragment of \(m/z=30\) does indeed exist, although its intensity is very weak. Figure 3b shows the EI/MS, ESI/MS and MALDI/TOFMS spectra of 3,4-MBMB. As shown in the upper mass spectrum (EI), the parent ion (\(m/z=208\)) is not formed, whereas two fragment ions (\(m/z=58\), 177) are produced from the C\({}_{\beta}\)-C\({}_{\alpha}\) bond breakage. No peak can be observed from the C\({}_{\alpha}\)-N bond breakage again. The peak at \(m/z=58\) is the major fragment of 3,4-MBMB, suggesting that this is the most stable fragment ion that forms after electron impact. It is obvious in this case, the EI mode is not suited for rapid screening if it is dependent only on the major peak at \(m/z=58\). 3,4-MDMA shows similar pattern with 3,4-MBMB. In traditional method, 3,4-MDMA can be performed via reaction with acetic anhydride, which provides specific fragments (\(m/z=58\), 100 and 162), permitted its characterization [15]. However, while such a specific derivative-reagent is suitable for one compound, it may not be suitable for others. In contrast, stable protonated parent ions ([M+H]\({}^{+}\), \(m/z=208\)) can be clearly observed by means of ESI and MALDI modes (the middle and bottom mass spectra of Frame B, respectively). In the case of ESI/MS, \(\alpha\)-cleavage is the major process that would produce a fragment at \(m/z=177\), indicating the loss of a neutral fragment, \(208\,-\,177\) = 31 [NH\({}_{2}\)(CH\({}_{3}\))], but the peak from \(\beta\)-cleavage cannot be found. It should be noted that, in the case of MALDI/TOFMS, fragment ions from both \(\alpha\)-cleavage and \(\beta\)-cleavage could be observed, even though the fragment from \(\alpha\)-cleavage is insignificant. Figure 3c shows the EI/MS, ESI/MS and MALDI/TOFMS spectra of DET. A parent ion (\(m/z=217\)) is formed by the EI mode even though its intensity is insignificant, and two fragment ions (\(m/z=86\), 144) are produced from the C\({}_{\beta}\)-C\({}_{\alpha}\) bond breakage. In the case of ESI/MS, stable protonated parent ions ([M+H]\({}^{+}\), \(m/z=217\)) and two fragments (\(m/z=86\), 144), which are formed through \(\alpha\)-cleavage and \(\beta\)-cleavage processes, can be clearly observed. The \(\alpha\)-cleavage is the major process that would produce a fragment at \(m/z=144\), indicating the loss of a neutral fragment, \(217\,-\,144\) = 73 ([NH(CH\({}_{2}\)CH\({}_{3}\))\({}_{2}\)]). Meanwhile, the \(\beta\)-cleavage process also occurs, in which a peak at \(m/z=58\) [H\({}_{2}\)C=N\({}^{+}\)(CH\({}_{3}\))\({}_{2}\)] was observed, indicating the loss of a larger neutral fragment, \(217\,-\,86\) = 131. The ion intensity order of DMT is as follows: [M+H]\({}^{+}>>\) fragment formed by the \(\alpha\)-cleavage process \(>\) fragment formed by the \(\beta\)-cleavage process. In the case of MALDI/TOFMS, the ion intensity of [M+H]\({}^{+}\) is greater than the fragment from the \(\beta\)-cleavage process, but the fragment (\(m/z=144\)) from \(\alpha\)-cleavage is missing.