A standard autoinjector (Shimadzu AOC-20i) was upgraded with a dedicated program and applied for the automatic operation of micro extraction by packed sorbent (MEPS) instead of an expensive multipurpose autosampler to carry out a confirmation analysis of methamphetamine, amphetamine, 3,4-methylenedioxymethamphetamine and 3,4-methylenedioxyamphetamine in hair by gas chromatography/mass spectrometry. Specification of the inlet liner, which is important for large volume injection utilizing programmable temperature vaporization (PTV), was studied, and lifetime of the liner was evaluated by repetitive analyses. By utilizing this system, full-scan electron-ionization mass spectra that were identical to the authentic acetylated analytes were observed using 3 mg of a fortified hair sample at 0.20 ng mg⁻¹, which was more sensitive than the previous system. Although the lifetime of the inlet liner was relatively short (12-13 times use), this system is beneficial for the confirmation analysis of amphetamine-type stimulants in hair.