4th EucheMs chemistry congress

Poster Session 2
s1143
chem. Listy 106, s257–s1425 (2012)
Poster session 2 - Analytical Chemistry
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nitroMethAne eLeCtroCheMiCAL SenSinG
Method for An exPLoSive trACe deteCtor By
ConCentrAtion in Liquid MediA
e. PASquinet 1 , S. deLiLe 1 , t. MAiLLou 1 , P. PALMAS 1 ,
M. BouSquet 1 , S. BeAuGrAnd 1 , v. LAir 2 , M. CASSir 2
1 Cea Le Ripault, DXPL, Monts, France
2 Chimie ParisTech, ENSCP, Paris, France
During the past ten years, the terrorism menace has
increased and the development of efficient explosive detection
devices has become an urgent worldwide necessity. In this
context, the CEA (Commissariat l’Energie Atomique et aux
Energies Alternatives) started several projects aimed at developing
detectors of explosives traces. Nebulex is a patented device which
solubilises vapors or particles of explosive (or precursor) in a tank
via a spray formation. The solubilised molecules can be detected
in-situ using an adapted reagent to a technique of detection. First,
colorimetric and fluorescent methods were used in associate with
specific reagents developed for peroxides detection. In this study,
we evaluated electrochemistry as a new method for the detection
of a nitro compound, the nitromethane.
Whereas aromatic nitro compounds such as trinitrotoluene
(TNT) have already been widely studied, nitromethane doesn’t
seem to have attracted much interest. Nitromethane is a
constituent of artisanal explosive compositions, and like the other
nitro compounds, it can be detected by the electrochemical
reduction of the NO group. The objective of this study is to define
2
and optimize conditions for the detection with a simple and robust
system of electrodes.
The higher intensity of reduction was obtained in neutral
media and by using a gold electrode with a simple system. In these
conditions, a limit of detection (LOD) of 3 µmol/L of
nitromethane was achieved in the absence of dissolved oxygen.
In air environment, which is more representative of real condition
encountered with Nebulex device, the LOD grows to 12 µmol/L
due to increase of noise.
An important constraint imposed by the project is to
minimize the system for a portable application in the Nebulex
device. For this, a portable potentiostat and a screen-printed
electrodes system were evaluated and compared with laboratory
equipment.
Keywords: electrochemistry; sensors; trace analysis;
4 th EucheMs chemistry congress
P - 0 5 6 3
MASS SPeCtroMetriC APProACh to
evALuAtion of hiStoriCAL PAintinGS By
identifiCAtion of PruSSiAn BLue And indiGo
v. PAuK 1 , B. PAPouSKovA 1 , P. SuLovSKy 2 , K. LeMr 1
1 Palacky University in Olomouc, Department of Analytical
Chemistry RCPTM, Olomouc, Czech Republic
2 Palacky University in Olomouc, Department of Geology,
Olomouc, Czech Republic
Prussian blue and indigo are very famous and widely used
blue pigments. They often exhibit similar properties in paintings
and they are highly insoluble in water and common organic
solvents. Prussian blue is the synthetic pigment discovered at the
beginning of the 18th century in Berlin, natural indigo was
produced from plant material since ancient times and used up to
the end of the 19th century when it was replaced by the synthetic
dye.
The aim of this work was to develop a fast and sensitive
method for analysis of both pigments of high historical
importance.
The experiments were performed using a Q-TOF Premier
mass spectrometer (Waters, Manchester, UK) by flow injection
analysis with negative electrospray ionization. The compounds
were subsequently detected after simple sample preparation based
on two chemical reactions in alkaline solution: decomposition of
Prussian blue and reduction of indigo with dithionite to soluble
leucoindigo.
The main advantage of the developed procedure is that no
chromatographic separation is required. The proposed method is
fast (2 minutes runtime), very sensitive (LODs for Prussian blue
and indigo are 47 pg and 59 pg in injection, respectively) and has
a wide dynamic range (linear calibration was observed from 10
to 5000 ng/mL, injection volume 5µL).
The method was successfully applied for identification of
Prussian blue in samples taken from the painting of ‘Crucifixion’,
St. Sebestian church on St. Hill in Mikulov, Czech Republic, and
results were confirmed by Raman spectroscopy. This technique
can be used for fast screening of two blue pigments in small
samples of historical and art objects.
Acknowledgement: The support by the Ministry of Education,
Youth and Sports of the Czech Republic (ME10013),
Operational Program Research and Development for
Innovations - European Regional Development Fund (project
CZ.1.05/2.1.00/03.0058) and by Palacky University
(PrF_2012_020) is gratefully acknowledged.
Keywords: Mass spectrometry; Dyes/Pigments;
AUGUst 26–30, 2012, PrAGUE, cZEcH rEPUbLIc