Fig. 1. Hardware configuration of the multicolumn Deans switch GC–MS system used. (A) The solenoid valve is in the off position and effluent from the primary column is flowing to the exit gas line. (B) The solenoid valve is in the on position, allowing effluent to flow to the 2D GC separation column prior to MS detection.

Fig. 2. MDGC–MS chromatograms of two consecutive chromatographic runs from the same sample vial in scanning mode (m/z 50–400). (A) All effluent was directed after 0.26 min to the 2D GC separation (B) Only the selected heart-cuts (which were identical to the finally validated method) were transferred to the 2D. Both methods were otherwise identical to the final method, but the final temperatures were (A) 275 °C and (B) 250 °C. Temperature ramp rate in (A) was 50 °C min⁻¹ between 250 and 275 °C. For other conditions, see Section 2. The compounds included were AM, MA, MDA, MDMA, MDEA, ephedrine (Eph), pseudoephedrine (pEph), norpseudoephedrine (norpEph), methylphenidate (MePh) (4000 ng ml⁻¹ each) and MA-d₅ (500 ng ml⁻¹).

Fig. 3. Deans switch continual flow heart-cutting and fast MDGC–MS separation of AM, MA, MDA, MDMA and MDEA. For instrumental information, Deans switch settings, fast GC conditions and MS detection parameters, see Section 2. The spiked whole blood sample used as the second highest calibration standard (2000 ng ml⁻¹ each) is illustrated as (A) a total ion chromatogram (TIC) of all the selected SIM ions and (B) extracted ion chromatograms of each ion trace detected. The peak numbering is shown as in Table 1 and the SIM ion time windows are marked with dashed lines.

Fig. 4. Examples of two positive authentic whole blood samples taken from individuals suspected of driving a car under the influence of drugs. (A) AM (506.5 ng ml⁻¹) and (B) MA (104.7 ng ml⁻¹). (Left) Extracted ion chromatograms of each ion trace of the target compound and IS, (right) target ion overlay chromatograms of the four lowest calibration standards (1000, 500, 50, 25 ng ml⁻¹), authentic whole blood sample and a zero whole blood sample including ISs. The target ion of each target analyte or IS is underlined.

SIM parameters of fast MDGC–MS run

Internal standard (IS) used for each analyte, as well as determination coefficients (R²) of calibration curves using linear regression model with a weighting factor of the inverse of the squared concentration (1/x²) and average relative standard deviation (RSD) of concentration points (n = 6 each)

Accuracy, within-day (repeatability) and time-different intermediate precision as well as S/N ratio at LOQ level for each analyte

The resolution (R_s) between peak pairs of ATS drugs by fast MDGC–MS method presented in comparison with conventional one-column GC–MS approach [17]