Taguchi’s method in optimizing the experimental conditions of simultaneous supercritical fluid extraction and chemical derivatization for the gas chromatographic-mass spectrometric determination of amphetamine and methamphetamine in aqueous matrix

With the aid of gas chromatography-mass spectrometry (GC-MS), a systematical and analytical evaluation method called Taguchi’s quality engineering has been applied to the in-situ supercritical fluid extraction (SFE) and chemical derivatization (ChD) of amphetamines from water to afford the optimal experimental conditions and hence achieved the highest recoveries of the analytes (as their trifluoroacetyl derivatives) and the best robustness of the quatitation out of the least number of experimental runs. The optimal levels thus determined for the four influential factors are: pressure, 4000 psi; temperature, 90 ̊C; time for static SFE, 5 min; amount of TFA (ChD agent), 100 μL. Also, the mean recoveries achieved by simultaneous SFE-ChD, i.e., 95% (rsd = 3.8%) for AP and 89% (rsd = 4.0%) for MA, are significantly better than the corresponding overall recoveries obtained upon stepwise SFE-ChD, suggesting the unreacted TFA in the former procedure has strengthened the extracting power of CO2 fluid as has been evidenced by a control test. The success of this study has significantly strengthened the base and broadened the usefulness of both simultaneous SFE-ChD and Taguchi’s method.