A desktop NMR spectrometer was used to qualitatively analyze samples in drug-related cases in order to enhance the accuracy of the results and identify new drugs. Twelve known drugs and their derivatives were used to establish the parameters, conditions, and procedures for the methods and validate the feasibility and reliability of the methods. First, 1-D and 2-D NMR data for these 12 drugs and their derivatives were obtained in detail using a 600-MHz NMR spectrometer to create a data library. Next, some of these 12 drugs were analyzed using a Picospin 80 MHz desktop NMR spectrometer to set up the analytical procedure and method. With the procedure and method established, real case samples were analyzed and the data were compared to those obtained by a standard method. The results indicate that the desktop NMR spectrometer is a reliable and promising approach that can be used in criminology to quickly identify whether or not samples contain illegal drugs.
Traditional detection methods for illicit drugs in the laboratory mainly include immunoassay [
Nuclear magnetic resonance (NMR) is a highly efficient method for structure elucidation in the fields of chemistry and biology [
In this paper, a set of feasibility and reliability methods will be established to analyze drug samples from criminology using a desktop NMR spectrometer. To achieve this goal, we used three well-known drug families (morphine, amphetamine, and ketamine), including morphine, heroin, 3-
Chemical structures of twelve drugs.
Twelve standard drugs and illegal samples were authorized by the Public Security of Guangxi Province. Deuterium oxide (D2O), containing 0.05 wt.% 3-(trimethylsilyl) propionic-2,2,3,3-
The 1H NMR spectra were acquired using 64 K data points with a spectral width of 12019 Hz, the acquisition time of 2.73 s, the relaxation delay of 1 s, 16 scans, and a pulse width of 30°. The 13C NMR spectra were acquired using 64 K data points with a spectral width of 36232 Hz, the acquisition time of 0.91 s, the relaxation delay of 2 s, 1024 scans, and a pulse width of 30°. DEPT 90 and DEPT 135 spectra were performed using 64 K data points with a spectral width of 24038 Hz, the relaxation delay of 6.50 s, and 512 scans. The parameters used for the COSY spectra were 12019 Hz, an acquisition time of 0.21 s, a relaxation delay of 2 s, and 12 scans. HSQC experiments were recorded using the hsqcetgpsisp 2.2 pulse sequence with 24 scans. The spectral widths of the F1 (13C) dimension and the F2 (1H) dimension were 36232 Hz and 12019 Hz, respectively. The HMBC spectra were acquired using the hmbcgplpdqf pulse sequence with 80 scans. The spectral widths of the F1 (13C) dimension and the F2 (1H) dimension were 36232 Hz and 12019 Hz, respectively. Two-dimension selective HSQC (shsqcetgpsisp2.2) was performed in DAM with 24 scans.
The limits of detection for the 600-MHz 1H NMR spectra were acquired using 160 scans (8 min) and acquisition parameters similar to the abovementioned 1H NMR spectra. The 1H NMR spectra using the Picospin 80 desktop NMR spectrometer required 480 scans at 309 K with a bandwidth of 4 KHz.
The GC column was a DB-5ms capillary column (30 m × 0.2 mm × 0.25
The mass spectrometer was operated in electron impact (EI) mode with a mass range of 40–500 U. The temperature of the MS source was 200°C. The electron ionization voltage was set at 70 eV.
The following masses were used for the drug standards: 10 mg for morphine, heroin, 3OM, 6OM, codeine, and DAM; 4 mg for amphetamine, MAM, KE, and MDMA; 8.6 mg for ACD; and 3.5 mg for MDA. These standard drugs were dissolved in 0.5 mL D2O, and the solutions were transferred into 5 mm NMR tubes for the NMR analysis. To achieve 2- or 5-fold dilution, respectively, 0.25- or 0.1-mL sample solutions were diluted with D2O to 0.5 mL.
For the desktop NMR analysis, the masses of morphine and MAM used were 50 mg. The masses of codeine, real crime sample 1 (S1), and real crime sample 2 (S2) were 80 mg. The samples for the desktop NMR experiments were dissolved in 0.5 mL of millipore water. The solution was filtered through a syringe filter (0.45
Case samples 1 (S1) and 2 (S2) weighed 5 mg and were dissolved in 5 mL methanol in a vial for the GC-MS analysis.
The 1H NMR data for morphine and its derivatives are shown in Table
1H NMR data for morphine, heroin, 3OM, 6OM, codeine, and ACD in 0.5 mL D2O.
| | | | | | |
---|---|---|---|---|---|---|
H1 | 6.71, d | 6.90, d | 6.85, d | 6.74, d | 6.80, d | 6.84, d |
H2 | 6.79, d | 6.99, d | 6.97, d | 6.82, d | 6.93 | 6.94, d |
H5 | 5.09, d | 5.31, d | 5.14, d | 5.24, d | 5.10, d | 5.30, d |
H6 | 4.20, d | 5.34, d | 4.42, d | 5.30, m | 4.40, d | 5.32, d |
H7 | 5.76, d | 5.62, d | 5.78, d | 5.58, d | 5.76, d | 5.75, d |
H8 | 5.41, d | 5.77, d | 5.44, d | 5.77, d | 5.42, d | 5.60, d |
H9 | 4.24, s | 4.28, s | 4.26, s | 4.20, s | 4.25, s | 4.25, s |
H10 | 2.95,3.31, d | 3.04,3.39, s | 3.04,3.36, m | 2.98,3.25, d | 3.40,2.96, d | 3.04,3.32, s |
H14 | 3.02, s | 3.18, s | 3.04, m | 3.14, s | 3.02, s | 3.15, s |
H15 | 2.36,2.15, d | 2.36,2.17, s | 2.21,2.39, m | 2.13,2.36, m | 2.16, 2.37, d | 2.10,2.36, d |
H16 | 3.40,3.10, d | 3.04,3.39, s | 3.17,3.35, m | 3.38,3.08, m | 3.10,3.41, s | 3.37,3.04, m |
H17 | 3.02, s | 3.04, s | 3.04, s | 3.04, s | 3.02, s | 3.04, s |
H18 | N/A | N/A | N/A | N/A | 3.87, s | 3.87, s |
H19 | N/A | 2.17, s | 2.36, s | 2.20, s | N/A | N/A |
H20 | N/A | N/A | N/A | N/A | N/A | 2.19, s |
H21 | N/A | 2.36, s | N/A | N/A | N/A | N/A |
The 13C NMR spectrum of 3OM.
The 1H NMR chemical shifts for amphetamine, methamphetamine, DAM, MDA, and MDMA are summarized in Table
1H NMR chemical shifts for AM, MAM, KE, DAM, MAD, and MDMA.
| | | | | | |
---|---|---|---|---|---|---|
H2 | 7.33, d | 7.34, d | 7.37, d | 6.86, s | 6.86, s | N/A |
H3 | 7.44, t | 7.44, t | 7.45, t | N/A | N/A | 1.92,3.35, m |
H4 | 7.38, t | 7.38, t | 7.40, t | N/A | N/A | 1.80,1.92, m |
H5 | 7.44, t | 7.44, t | 7.45, t | 6.90, d | 6.90, d | 1.80,2.15, m |
H6 | 7.33, d | 7.34, d | 7.37, d | 6.80, d | 6.80, d | 2.65, d |
H7 | 2.96, m | 2.92,3.10, m | 2.91,3.16, m | 2.87, m | 2.86,2.98, m | N/A |
H8 | 3.65, m | 3.56, m | 3.73, m | 3.60, m | 3.50, m | 7.90 |
H9 | 1.32, d | 1.30, d | 1.27, d | 1.32, d | 1.28, d | N/A |
H10 | N/A | 2.72, s | 2.88, s | 5.98, s | 2.71, s | 7.63, m |
H11 | N/A | N/A | 2.88, s | N/A | 5.99, s | 7.63, m |
H12 | N/A | N/A | N/A | N/A | N/A | 7.63, m |
H13 | N/A | N/A | N/A | N/A | N/A | 2.43, s |
These 1H NMR data for morphine and amphetamine derivatives have been reported in previous studies [
To obtain the limits of detection for these 12 standard drugs using the 600-MHz NMR spectrometer, we used morphine, codeine, ACD, MAM, and DAM. The amounts of each drug in the NMR samples after each dilution are given in Table
The amounts (mg) of morphine, codeine, ACD, MAM, and MAD used in the dilution experiment.
| | | | | | | |
---|---|---|---|---|---|---|---|
Morphine | 10 | 2 | 0.4 | 0.08 | 0.016 | 0.008 | 0.0032 |
Codeine | 10 | 2 | 0.4 | 0.08 | 0.016 | 0.008 | 0.0032 |
ACD | 1.2 | 0.24 | 0.048 | 0.0096 | 0.0048 | 0.00192 | N/A |
MAM | 4 | 0.8 | 0.16 | 0.032 | 0.0064 | 0.0032 | 0.00128 |
MDA | 3.5 | 0.7 | 0.14 | 0.028 | 0.0056 | 0.0028 | 0.00112 |
1H NMR spectra for different amounts of morphine.
1H NMR spectra for different amounts of MAM.
The limit of detection is one of the important performance parameters for an instrument. The specifications of the Picospin 80 MHz desktop NMR spectrometer show that the detection limit is 0.1 mol. Figures
The 80 MHz 1H NMR spectra of water and codeine.
The 80 MHz 1H NMR spectra of water and MAM.
S1 and S2 are real samples from crime scenes. Figure
The 1H NMR spectra of S1, heroin, and acetylcodeine.
The GC chromatograms for S1 (a) and S2 (b).
Based on the standard 1H NMR spectra, the characteristic signals at 1.34, 2.81, and 7.38 were assigned to MAM (Figure
The 1H NMR spectra for S2, MDMA, MAM, and KE.
These experiments suggest that the desktop NMR spectrometer can effectively detect drugs by observing the methyl and benzyl ring peaks of standard samples. In addition, the desktop NMR can also provide information about unknown substances.
In this work, we successfully obtained a library containing the spectra of 12 standard drugs using a 600 MHz NMR spectrometer and mastered the desktop NMR spectrometer. Both morphine and amphetamine derivatives had low limits of detection using the 600-MHz 1H NMR spectra. Two real case samples were analyzed to verify the reliability of the desktop NMR spectrometer. Based on the characteristic peaks in the 1H NMR spectra of the standard drugs, the results showed that one sample mainly contained morphine and acetylcodeine, while the other contained MAM and MDMA. In conclusion, the desktop NMR spectrometer is an effective qualitative method for the analysis of drugs. We hope that desktop NMR spectrometers can be applied in case scenes in the future to analyze drugs from crimes.
The data used to support the findings of this study are available from the corresponding author upon request.
The authors declare that there are no conflicts of interest regarding the publication of this paper.
This research was supported by the Guangxi Science and Technology Department (no. Guikeneng1598025-2).
The supplementary materials include Picospin 80 desktop NMR spectrometers, the 600 MHz NMR spectra of five samples (including morphine, heroin, 6-