Illicit Drugs
Introduction
The detection of drugs plays an important role in many areas of society. In particular, the ability to detect and identify illicit drugs can assist law enforcement and other organizations in tracking and monitoring drug related activities. However, techniques that can be used outside the laboratory settings are often inefficient and non-specific. Gas Chromatography Mass Spectrometry (GC/MS) provides the most definitive results. With GC/MS, each compound, upon separation, ionization, and detection, produces a retention time and mass spectrometric pattern (similar to fingerprinting or signature) that are unique to the compound. Historically, the use of GC/MS systems has been limited by accessibility, cost, and mobility.
The Griffin 450 GC/MS system, based on compact cylindrical ion trap (CIT) technology(1,2), possesses the capability and specificity mentioned above, while also providing for sufficient mobility and cost-efficiency. This application note illustrates the detection, identification, and quantitation of commonly abused drugs - methamphetamine, cocaine, and heroin.
Figure 1. Griffin 450 Mobile GC/MS with Air Sampling
Instrumentation
- Griffin 450 GC/MS system
- Griffin System Software - GSS 3.2
Data Analysis
Database Search - NIST, Griffin, or User-Defined
Results /Discussion
Separation and Detection
A short analysis time of less than 12 minutes is achieved using the high temperature ramping rate offered by the Griffin 450 GC/MS system. Figure 2 shows the Total Ion Chromatogram (TIC) and Reconstructed Ion Chromatogram (RIC) at 10 ng injection on column.
The mass spectrum of each analyte detected resembles that in the NIST library, which provides the basis for identification of the drugs detected. Figure 3 shows the typical electron ionization (EI) mass spectra obtained with the Griffin 450 GC/MS system in comparison to those in the NIST library. For methamphetamine at higher concentration levels, the presence of the m/z 150 ion is due to the formation of MH+ from a chemical ionization mechanism. This ion, while interfering with the database searching, can be an effective qualifier ion, providing additional confirmation.
Calibration
- Calibration was performed at 0.25, 0.5, 1, 2.5, 5, 10, and 25 ng/µL levels for Methamphetamine.
- Calibration was performed at 0.1, 0.25, 0.5, 1, 2.5, 5, 10, and 25 ng/µL levels for Cocaine.
- Calibration was performed at 2.5, 5, 10, 25, and 50 ng/µL levels for Heroin.
Figure 2. TIC Chromatogram (Blue) and RIC Chromatogram (Red) at 10 ng injected: Methamphetamine RIC (m/z 58), Cocaine RIC ( m/z 82), and Heroin RIC (m/z 327)
Fgure 3. EI MS Spectrum of methamphetamine, cocaine, and heroin at 10 ng injected. The top trace in each graph is the result from Griffin 450 and the bottom trace from the NIST Library.
Detection Limit
For quantitation purposes using single ion RIC, detection limits are 250 pg, 250 pg, and 5000 pg for methamphetamine, cocaine, and heroin on column, respectively.
Reproducibility
The reproducibility is presented as relative standard deviations calculated for replicate analyses for each compound. Peak area Relative Standard Deviation (RSD) values are 9.8%, 9.1%, and 10.3 % for methamphetamine, cocaine, and heroin respectively, measured by the quant ion RIC area from four 10 ng injections. Retention time RSD is generally less than 0.15% for the three compounds.
____________________________________________
These data represent typical results.
Conclusions
The Griffin 450 Mobile GC/MS system can be used for the detection and identification of illicit drugs, such as methamphetamine, cocaine, and heroin in a single run.
References
1. Wells, J.M.; Badman, E.R.; Cooks, R.G. Anal. Chem. 1998, 70, 438-444.
2. Patterson, G.E.; Guymon, A.J.; Riter, L.S.; Everly, M.; Griep-Raming, J.; Laughlin, B.C.; Ouyang, Z.; Cooks, R.G. Anal. Chem. 2002, 74, 6145-6153.