Universidade de São Paulo
Faculdade de Filosofia Ciencias e Letras de Ribeirão Preto
Departamento de Química
Voltammetric detection of LSD using a chemically
modified carbon paste electrode with Schiff base
complex
Marcelo Firmino de Oliveira
Drug analysis by american CSIs and Brazilian Federal Police
Class A
Class B
Class C
CE
Spot tests
GC
fluorescence
TLC
Immunological assay
HPLC
Melting point
Optical microscopy
UV-Vis
FTIR
A+A
A+B
A+C
B+B+B
MS
H-RMN
Raman
B+B+C
Farmaceutical identifiers
PS: no electrochemical methods cited
Cell, electrodes and expected results in voltammetry
Example of electrochemical analysis in forensic chemistry:
Cocaine
(SWV: LOD of 1nmol/L)
V. Pavlova et al. / Analytica Chimica Acta 512 (2004) 49–56
LSD
1938 – Dr. Albert Hofmann
d-LSD
d-iso-LSD
Lysergic acid + diethylamide
l-LSD
l-iso-LSD
Actuation: CNS
 hallucinations;
 euphoria;
 panic;
 confusion;
 psychotic episodes.
Chemical modifier
 Schiff Bases:
 1864 – Hugo Schiff
 Amine + Aldehyde/Ketone
 applicability :
 antimicrobial
 Fungicide
 Herbicide
 Anticancer
 Complexation with metallic
centers: UO22+
OBJECTIVES
 Apply the complex [UO2(Ac-ophen)]·H2O as carbon
paste electrode modifier;
 Voltammetric detection and quantification of LSD.
Experimental
40%
20%
40%
CV
SWV
DPV
KCl 0.1M
Results
Standard addition – SWV
Frequency: 10 Hz
Amplitude: 800 mV
a)
250
0,00 mol L LSD
-1
1,02 mol L LSD
-1
2,05 mol L LSD
-1
3,04 mol L LSD
-1
4,06 mol L LSD
200
Peak 
Peak 
260
240

220

I / A
300
I / A
b)
-1
350
150
200
180
100
50
160
0
140
-0,8
-0,4
0,0
0,4
E / V vs. Ag/AgCl (saturado)
0,8
1,2
0
1
2
CLSD / mol L
3
-1
4
Standard addition - DPV
Amplitude: 800mV
pulse time: 40ms
a)
b)
160
140
-1

120

80
Peak 
Peak 
130
I / A
I / A
120
0,00 mol L LSD
-1
1,02 mol L LSD
-1
2,05 mol L LSD
-1
3,07 mol L LSD
-1
4,09 mol L LSD
110
100
40
90
80
0
-1,0
-0,5
0,0
0,5
E / V vs. Ag/AgCl (saturado)
1,0
0
1
2
CLSD / mol L
-1
3
4
Voltammetric
technique
SWV
DPV
R2
SD
(μA)
m
LOD
(μA L μmol-1) (μmol L-1)
LOQ
(μmol L-1)
0.992 1.79x10-2
1.75x10-1
0.31
1.02
0.984 2.63x10-2
1.52x10-1
0.52
1.73
CONCLUSIONS
A new transductor for LSD analysis;
 Detection and quantification of LSD μmol L-1 range;
Good stability for the proposed CM-CPE in water.
Thank you