TWO-STAGE SYNTHETIC DRUGS DISCRIMINATION IN BLOTTER … · 0,05 0,1 0,15 0,2 0,25 0,3 0,35 Número...
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Custódio, M. F. 1 , Magalhães, L. O . 1 , Arantes, L. C. 2 , Braga, J. W. B. 1 TWO-STAGE SYNTHETIC DRUGS DISCRIMINATION IN BLOTTER PAPERS BY MIR SPECTROSCOPY AND PLS-DA 1 Instituto de Química, Universidade de Brasília, DF, Brasil. 2 Instituto de Criminalística, Seção de Perícias e Análises Laboratoriais, Polícia Civil do Distrito Federal, DF, Brasil. *[email protected] NEQUIFOR Introduction and Objective Methods Conclusions Results ➢ Blotter paper seizures containing new psychoactive substances (NPS) such as NBOMe and NBOH are increasing over the last years. ➢ Usually blotter paper analysis is performed by GC-MS. ➢ NBOH compounds need an ambient ionization or a modified GC-MS method to avoid misidentification with 2C-I. 1 ➢ Spectroscopic methods such as ATR-FTIR associated to PLS-DA are an alternative for a rapid sceening of NPS in blotter papers. ➢ The objective of this work is the development of a two-stage discrimination method for NPS in blotter papers using ATR-FTIR and PLS-DA. Spectra acquisition MODEL A (PLS-DA) NO NPS NPS MODEL B (PLS-DA) NBOMe NBOH OTHERS 500 1000 1500 2000 2500 3000 3500 4000 0 0,05 0,1 0,15 0,2 0,25 0,3 0,35 Número de onda / cm -1 Absorbância / u. a. GC-MS End of analysis Outlier Sample can’t be analyzed by the model Outlier 156 samples MODEL A – 13 latent variables Phase Class FPR (%) FNR (%) EFR (%) Training No NPS 0 0 100 NPS 0 0 100 Validation No NPS 0 0 100 NPS 0 0 100 MODEL B – 9 latent variables Fase Class FPR (%) FNR (%) EFR (%) Training NBOMe 0 0 100 NBOH 0 0 100 Validation NBOMe 0 0 100 NBOH 0 0 100 ➢ This is a cheap and fast non-destructive procedure, which requires no sample preparation and can be performed in less than ten minutes in a standard ATR-FTIR. ➢ The proposed method presented efficiency rates of 100% and can be easily updated to include new drugs or drug classes. 2 ➢ Outliers are rapidly identified considering superior and inferior limits as well as Mahalanobis distance and spectral residual probability. ➢ The proposed method can be used as a blotter paper screening routine in forensic laboratories. References Acknowledgments X X N __ H C __ O Blank Wavenumber / cm -1 1 Arantes, L.C.; Ferrari Júnior, E.; Souza, L.F.; Cardoso, A.C.; Alcântara, T.L.F.; Lião, L.M.; Machado, Y.; Lordeiro, R.A.; Coelho Neto, J.; Andrade, A.F.B. Forensic Toxicol. 35 (2017) 408-414. doi: 10.1007/s11419-017-0357-x. 2 Pereira, L.S.A.; Lisboa, F.L.C.; Coelho Neto, J.; Valladão, F.; Sena, M. Microchem. J. 133 (2017) 96–103. doi:10.1016/j.microc.2017.03.032. Figure 1. Characteristic spectra of blank and studied substances. Figure 2. (A) Estimated class values and (B) spectral residual probability versus Mahalanobis distance for Model A. FPR - False positive rate FNR - False negative rate EFR – Efficiency rate. Figure 3. (A) Estimated class values and (B) spectral residual probability versus Mahalanobis distance for Model B. Table 1. Figures of merit for models A and B. C __ I GC-MS or API-MS (A) (A) (B) (B)
Transcript of TWO-STAGE SYNTHETIC DRUGS DISCRIMINATION IN BLOTTER … · 0,05 0,1 0,15 0,2 0,25 0,3 0,35 Número...
Custódio, M. F. 1, Magalhães, L. O. 1, Arantes, L. C. 2, Braga, J. W. B. 1
TWO-STAGE SYNTHETIC DRUGS DISCRIMINATION IN
BLOTTER PAPERS BY MIR SPECTROSCOPY AND PLS-DA
1 Instituto de Química, Universidade de Brasília, DF, Brasil.2 Instituto de Criminalística, Seção de Perícias e Análises Laboratoriais, Polícia Civil do Distrito Federal, DF, Brasil.
NEQUIFOR
Introduction and Objective
Methods
ConclusionsResults
➢ Blotter paper seizures containing new psychoactive substances
(NPS) such as NBOMe and NBOH are increasing over the last years.
➢ Usually blotter paper analysis is performed by GC-MS.
➢ NBOH compounds need an ambient ionization or a modified GC-MS
method to avoid misidentification with 2C-I.1
➢ Spectroscopic methods such as ATR-FTIR associated to PLS-DA are
an alternative for a rapid sceening of NPS in blotter papers.
➢ The objective of this work is the development of a two-stage
discrimination method for NPS in blotter papers using ATR-FTIR and
PLS-DA.
Spectra
acquisition
MODEL A
(PLS-DA)
NO NPSNPS
MODEL B
(PLS-DA)
NBOMe
NBOH
OTHERS
500 1000 1500 2000 2500 3000 3500 40000
0,05
0,1
0,15
0,2
0,25
0,3
0,35
Número de onda / cm-1
Ab
so
rbâ
nc
ia / u
. a
.
GC-MSEnd of
analysis
Outlier
Sample can’t be analyzed
by the model
Outlier
156 samples
MODEL A – 13 latent variablesPhase Class FPR (%) FNR (%) EFR (%)
TrainingNo NPS 0 0 100
NPS 0 0 100
ValidationNo NPS 0 0 100
NPS 0 0 100MODEL B – 9 latent variables
Fase Class FPR (%) FNR (%) EFR (%)
TrainingNBOMe 0 0 100NBOH 0 0 100
ValidationNBOMe 0 0 100NBOH 0 0 100
➢ This is a cheap and fast non-destructive procedure, which requires
no sample preparation and can be performed in less than ten
minutes in a standard ATR-FTIR.
➢ The proposed method presented efficiency rates of 100% and can
be easily updated to include new drugs or drug classes.2
➢ Outliers are rapidly identified considering superior and inferior limits
as well as Mahalanobis distance and spectral residual probability.
➢ The proposed method can be used as a blotter paper screening
routine in forensic laboratories.
References
Acknowledgments
X
X
N__H
C__O
Blank
Wavenumber / cm-1
1 Arantes, L.C.; Ferrari Júnior, E.; Souza, L.F.; Cardoso, A.C.; Alcântara, T.L.F.; Lião,
L.M.; Machado, Y.; Lordeiro, R.A.; Coelho Neto, J.; Andrade, A.F.B. Forensic Toxicol. 35
(2017) 408-414. doi: 10.1007/s11419-017-0357-x.
2 Pereira, L.S.A.; Lisboa, F.L.C.; Coelho Neto, J.; Valladão, F.; Sena, M. Microchem. J.
133 (2017) 96–103. doi:10.1016/j.microc.2017.03.032.
Figure 1. Characteristic spectra of blank and studied substances.
Figure 2. (A) Estimated class values and (B) spectral residual probability versus
Mahalanobis distance for Model A.
FPR - False positive rate FNR - False negative rate EFR – Efficiency rate.
Figure 3. (A) Estimated class values and (B) spectral residual probability versus
Mahalanobis distance for Model B.
Table 1. Figures of merit for models A and B.
C__I
GC-MS orAPI-MS
(A)
(A) (B)
(B)
