On the basis of the above results, we concluded that the internal standard was the intended compound, MDMPA, and that it was of a high purity.
Attempts to use isocratic conditions were unsatisfactory because optimal resolution of the three investigated compounds, which are secondary amines, produced retention times that were too long for the internal standard MDMPA, a tertiary amine, influencing its retention behavior.
The MS spectra obtained were dominated by an intense [[M+H].sup.+] peak (m/z 180.1 for MDA, m/z 194.1 for MDMA, m/z 208.1 for MDEA, and m/z 236.1 for MDMPA) and essentially a single major fragment ion at m/z 163.1, the same for all compounds.
In conclusion, we have established a reliable analytical method for MDA, MDMA, and MDEA quantification in whole blood, serum, vitreous humor, and urine that uses LC-Fl detection, liquid-liquid extraction, and internal standardization with a structurally related analog of the designer drugs, i.e., MDMPA. A simple methodologic crossover between LC-Fl detection and LC-MS/MS allowed successful validation of the results obtained by LC-Fl and enables complementary identification of analytes on the basis of their unique MS/MS spectra, generally considered vital in forensic applications.