4th EucheMs chemistry congress

Poster Session 2
s1130
chem. Listy 106, s257–s1425 (2012)
Poster session 2 - Analytical Chemistry
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A CoMPAriSon of MALdi MAtriCeS BASed on
LithiuM SALtS for AnALySiS of
hydroCArBonS And wAx eSterS
P. horKA 1 , v. vrKoSLAv 2 , K. PeCKovA 1 , J. CvACKA 2
1 Faculty of Science Charles University in Prague, Analytical
Chemistry, Prague 2, Czech Republic
2 Institute of Organic Chemistry and Biochemistry v.v.i.
Academy of Sciences of the Czech Republic, Mass
Spectrometry, Prague 6, Czech Republic
Matrix assisted laser desorption/ionization (MALDI) is an
effective method for a rapid characterization of lipid mixtures.
Data obtained from MALDI spectra are useful for quick
comparison of the samples composition or chemotaxonomic
purposes. MALDI is a suitable method for analysis of all classes
of lipids from complex polar lipids to simple and completely nonpolar
lipids. The processes taking place in MALDI are rather
complicated and have not been fully understood yet. The choice
of MALDI matrix depends on the analyte structure. For neutral
lipids only few effective matrices have been described. In this
work several new matrices based on lithium salts of organic
aromatic acids (lithium 2,5-dihydroxytereftalate, lithium
2,5-dimethoxybenzoate, lithium α-cyano-4-hydroxycinnamate,
lithium sinapate, lithium benzoate, lithium salicylate, lithium
vanillate) were tested as potential matrices for MALDI-MS
analysis of hydrocarbons (HCs) and wax esters (WEs). As shown
previously, the ionization of neutral lipids occurs via attachment
of lithium cation, which yields [M + Li] + adducts. The new
matrices were evaluated and compared with lithium
2,5-dihydroxybenzoate, which is a proven matrix for MALDI
analysis of lipids. Several parameters, including laser power,
sample deposition protocols and matrix to analyte ratio were
optimized for each matrix. The signal intensity and repeatability
was compared using standards (stearyl behenate, n-triacontane).
In addition, the nature of matrix ions and their range on m/z scale,
absorbance at laser wavelength 337 nm and solubility in various
solvents were studied. The morphology of the sample deposits
were discussed based on images taken from a scanning electron
microscope. The applicability of the matrices was tested on
natural samples (WEs from bees wax and plant waxes, insect
cuticular HCs). The best results were achieved with lithium
vanillate. It was found that effective matrices contain hydroxyl
group. A correlation between efficiency and a content of crystal
water in the matrix crystals was also observed.
Acknowledgement: This work was supported by Czech Science
Foundation GACR (Project No. 203/09/0139) and the Academy
of Sciences of the Czech Republic (Project RVO: 61388963).
Keywords: MALDI matrices; wax esters; hydrocarbons;
4 th EucheMs chemistry congress
P - 0 5 3 7
vCd Study of
1-PhenyLethyL-n,n-diMethyL-n-ALKyL
AMMoniuM BroMide
t. hruBy 1 , K. zuCeK 2 , v. SetniCKA 1
1 Institute of Chemical Technology in Prague, Department of
Analytical Chemistry, Prague 6, Czech Republic
2 Institute of Chemical Technology in Prague, Department of
Chemical Engineering, Prague 6, Czech Republic
The chiral derivatives of 1-phenylethyl-N,N-dimethyl-
-N-alkyl ammonium bromide are agents from group of
α-phenylethylamine, which is a well known and often used chiral
auxiliary, e.g. in chiral ligands for asymmetric catalysis, resolving
agent or in organocatalysts. Ammonium bromides are potentiall
agents for accelerated penetration of chiral drugs through the skin.
The compounds were investigated using vibrational circular
dichroism (VCD) spectroscopy. Experimental spectra of alkyl
ammonium bromides (alkyl R = 0, 8, 10, 12, 14, 16, 18 carbon
atoms) were measured in deuterated methanol in spectral region
of 1800 – 1200 cm-1 . Spectra were interpreted using a combination
with ab initio calculations based on density functional theory.
Results relevant to the conformation and absolute
configuration will be discussed.
Acknowledgement: The work was supported by the Ministry
of Education, Youth, and Sports of the Czech Republic
(Grant No MSM6046137307); the Czech Science Foundation
(Grant No P208/11/0105) and the Specific University Research
MSMT No 21/2012 - A1_FCHI_2012_003 and
A2_FCHI_2012_045.
The access to computing and storage facilities owned by parties
and projects contributing to the National Grid Infrastructure
MetaCentrum, provided under the programme “Projects of
Large Infrastructure for Research, Development, and
Innovations” (LM2010005) is highly acknowledged.
Keywords: Circular dichroism; Conformation analysis; Ab
initio calculations; Chiral auxiliaries;
AUGUst 26–30, 2012, PrAGUE, cZEcH rEPUbLIc