Table 1. List of the m/z values detected for drugs, their metabolites and their associated ion fragments via MS and MS/MS as well as the limits of detection observed in the two MALDI imaging experiments (spotted drug and high/low concentration spiking).
| Drug |
MALDI–QTOF–MS |
MALDI-QTOF-MS/MS |
MALDI-QTOF-MSI |
|||||
|---|---|---|---|---|---|---|---|---|
| Observed [M+H]+ & IS fragment | Difference (amu)* | m/z precursor →productions** | Ref | LOD ng/μL | LOD*** ng/cm2 | #Handling ng/cm2 | #Abuse ng/cm2 | |
| Amphetamine C9H13N C9H13N | 136.1371 [M+H]+ 91.0751 [ISF] | –0.0245 | 136 → 119, 91 | 24 | 10 | 2,96 | 189.5 | 18,95 |
| 4–MeAmph C10H15N | 150.1315 [M+H]+ | –0.0032 | 150 → 133, 105, 91 | 24 | − | − | − | − |
| MethAmph C10H15N | 150.1315 [M+H]+ | –0.0032 | 150 → 119, 91 | [24, 25] | − | − | − | − |
| MDMA C11H15NO2 | 194.1458 [M+H]+ 163.1017 [ISF] | –0.0277 | 194 → 163, 135,105,58 | [24, 25] | 1 | 0,88 | 189.5 | 18,95 |
| MDA C10H13NO2 | 180.1367 [M+H]+ 163.1015 [ISF] | –0.0343 | 180 → 163, 135,105,72 | [24, 25] | 1 | 0,88 | 189.5 | |
| MDEA C12H17NO2 | 208.1664 [M+H]+ 182.1474 [ISF] | –0.0327 | 208 → 163, 135, 105, 72 | [24, 26] | − | − | − | − |
| Cocaine C17H21NO4 | 304.1907 [M+H]+ 182.1474[ISF] | –0.0359 | 304 → 272, 182, 150, 82 | [24, 26] | 0,01 | 0,0088 | 189.5 | 0.19 |
| BZE C16H19NO4 | 290.1708 [M+H]+ 168.1270 [ISF] | –0.0316 | 290 → 272, 168, 150,82 | [24, 26] | 0,1 | 0,088 | 189.5 | 1,895 |
| EME C10H17NO3 | 200.1548 [M+H]+ 182.1495 [ISF] | –0.0262 | 200 → 182, 168, 150,82 | 26 | 0,1 | 0,088 | 189.5 | 1,895 |
| Methadone C21H27NO | 310.2474 [M+H]+ 265.1706 [ISF] | –0.0303 | 310 → 265, 247, 223,159,105 | 24 | − | − | − | − |
| Heroin C21H23NO5 | 370.1841 [M+H]+ 310.1846 [ISF] | –0.0187 | 370 → 328, 310, 286,211,193 | [24, 27] | 0,1 | 0,088 | 189.5 | 1,895 |
| 6–MAM C19H21NO4 | 328.1948 [M+H]+ 268.1733 [ISF] | –0.0400 | 328 → 310, 286, 211,193,165 | [24, 27] | 0,1 | 0,088 | 189.5 | 1,895 |
| Morphine C17H19NO3 | 286.1737 [M+H]+ | –0.0294 | 286 → 268, 211, 193,165 | [24, 27] | 0,1 | 0,088 | 189.5 | 1,895 |
| THC C21H30O2 | 315.2712 [M+H]+ | –0.0389 | 315 → 315, 300, 259,193,135,123 | 24 | 10 | 2,96 | 189.5 | 1,895 |
| THCA C21H28O4 | 345.2463 [M+H]+ | –0.0397 | 345 → 327, 299, 257,229,193 | 24 | 10 | 2,96 | 189.5 | 1,895 |
| 2 CB C10H1479BrNO2 | 260.0612 | 0.0326 | 28 | − | − | − | − | |
| C10H1481BrNO2 | 262.0647 | 0.0381 | 262 → 245, 230, 164 | |||||
| mCPP C10H13ClN2 | 197.0926 [M+H]+ | –0.0075 | 197 → 181, 154, 119,91 | 28 | − | − | − | − |
The table also reports MS/MS conditions and the literature references supporting structural confirmation and molecular identification.
*Calculated difference between measured m/z and calculated monoisotopic [M+H]+.
**MS/MS product ions obtained for structure elucidation, supported by previous studies.
***ng/cm2 as determined by dividing the amount of drug (volume/concentration) over the area of the applied spot (cm2) as shown in (see Fig. 3).
#ng/cm2 as determined by dividing the amount of drug (pure amount) over the area of a fingermark (~2.64 cm2) (see Fig. 4).