GC-MS and GC-IRD analysis of 2-, 3- and 4-methylmethamphetamine and 2-, 3- and 4-methylamphetamine

4-Methylmethamphetamine has been detected in samples submitted for analysis in several states throughout Australia. Six ring substituted methyl isomers of methamphetamine and amphetamine were synthesised and analysed. As the regioisomeric 2-, 3- and 4-methylmethamphetamine and 2-, 3- and 4-methylamphetamine have virtually identical mass spectra, the use of MS is an ineffective technique to discriminate between these closely related compounds. We set out to determine whether the regioisomers could be differentiated by a combination of GC-MS, acetyl derivatisation and GC-IRD. We demonstrate that the three isomers of methylmethamphetamine and methylamphetamine can be separated by GC, and a combination of acetyl derivatisation and vapour phase IR can identify the specific ring substituted compound.