Chemical signature of ecstasy volatiles by comprehensive two-dimensional gas chromatography.

A method for ecstasy volatiles 'signature' analysis based on two-dimensional gas chromatography separation and time-of-flight mass spectrometry detection (GC×GC-TOFMS) is presented. Organic impurity volatiles were extracted by head space solid phase microextraction (HS-SPME). The final column phase choice of the four different column combinations tested was a low-polarity 5% phenyl polysilphenylene-siloxane coupled with a polyethylene glycol phase, which best displayed the complex impurity profile. Second dimension ((2)D) retention time reproducibility was found to be about 1% RSD, and area reproducibility of SPME sampling was just over 5% RSD for compounds with S/N ratio of about 100. High similarity of TOFMS spectra of impurities was obtained against commercial MS libraries. 16 components from the two-dimensional profiles were selected for comparison of the 24 ecstasy tablets, most of which proved to be benzodioxole derived compounds. All tablets were correctly classified in eight groups according to their post-tabletting characteristics, when appropriate data pre-treatment was applied. Principal component analysis revealed clustering of samples according to the country of origin. Samples from Macedonia were elevated in N-formyl-MDMA and N-acetyl-MDMA while samples from Australia were elevated in 3,4-methylenedioxypropane and 3,4-methylenedioxyacetophenone. Furthermore, three components were found to be unique for one of the source countries. The additional separation of components on the (2)D column, increased response due to modulation, high acquisition rate with full mass spectra using TOFMS detection, and MS deconvolution extend the possibility of detecting additional markers and route-specific components, especially of low abundant, polar components.

Comprehensive two-dimensional gas chromatography--quadrupole mass spectrometric analysis of drugs.

The use of comprehensive two-dimensional gas chromatography coupled to quadrupole mass spectrometry (GC x GC-qMS) for drug screening is investigated with 77 underivatised drug standards in methanolic solution. The GC x GC-qMS setup involved a reduced mass scan range of 42-235 u and minimum quadrupole sampling time to achieve quadrupole scanning frequency of 19.36 Hz. Only 26% of the drugs investigated gave fair-to-acceptable library matches with full mass scan range commercial libraries. The creation of a new "truncated" library based on the mass spectra of the drug standards in the applied mass scan range of 42-235 u extends the feasibility of the currently adopted GC x GC-qMS approach to higher molecular weight compounds and is investigated with blank blood spiked with drug standards. With the new library, 75% of the drugs yielded matches of at least 90%. The time-of-flight mass spectrometer (TOFMS) is expected to address the limitations of the present GC x GC-qMS setup and a brief comparison between GC x GC-qMS and GC x GC-TOFMS is also provided in this study.

Comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry (GC x GC-TOFMS) for drug screening and confirmation.

Comprehensive two-dimensional gas chromatography (GC x GC) is applied to analysis of drug standard mixtures containing 78 drugs of interest in forensic samples. For this study, underivatised drugs were employed. While several of the drugs were not detected at the low concentrations employed in the samples, most could be satisfactorily assigned their first and second dimension retentions in the GC x GC retention plane. For this study, time-of-flight mass spectrometry (TOFMS) detection was used. The enhanced separation possible in GC x GC is demonstrated, and typical linearity and apparatus precision are shown for tramadol, diazepam, olanzapine and desipramine using selected qualifier ions. Mass spectral library search quality for the detection of drugs in a selection of authentic forensic cases, along with retention position in the 2D retention plane, is used to support positive identification of the presence of the drugs. The analysis of 'difficult' drugs paracetamol and phenytoin is shown to produce anomalous chromatographic peak shape in the 2D plane, whereas most drugs gave acceptable peak shapes. The GC x GC technique was applied to screening drugs in forensic samples, with either flame ionisation (FID) or TOFMS detection, and compared favourably with conventional single column GC-MS analysis when tested for diazepam in an authentic forensic study.