4th EucheMs chemistry congress

Poster Session 2
s1171
chem. Listy 106, s257–s1425 (2012)
Poster session 2 - food chemistry
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LC-eSi-MS/MS Study of ChLorAMPheniCoL
diStriBution on CheeSe MAKinG
d. yAnovyCh 1 , o. KoroBovA 1 , M. rydChuK 1
1 State Scientific Research Control Institute of Veterinary
Preparations, Laboratory of Instrumental Methods of Control,
Lviv, Ukraine
Chloramphenicol (CAP) is effective antibiotic, which use is
prohibited in food-producing animals. EU defined MRPL for CAP
in food of animal origin - 0.3 μg/kg. Chloramphenicol control in
raw milk is obligatory for cheesemakers. Since on manufacturing
CAP may concentrate in cheese, then there is possibility to obtain
contaminated product from allowable milk. Therefore, we
developed LC-ESI-MS/MS method for CAP residues
determination in cheese. Sample preparation was as follows: CAP
extraction with ethyl acetate from grated cheese, evaporation,
defatting and SPE clean-up. HPLC conditions: C column;
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mobile phase - water - methanol. Analyte was quantified by
negative ion mode LC-ESI-MS/MS (MRM of m/z 321≥152 and
321≥257). LOQ =0.02 μg/kg.
Since cheese sample matrix is complex, then minced cheese
fortifying with internal or external CAP standard may not
represent adequate recovery of analyte, present in initial milk.
Therefore, we prepared cheese reference matrix to estimate the
elaborated method’s recovery. Cheese was made in laboratory
according to general procedure using blank cow’s milk, divided
into two equal parts, one of which was spiked with 0.5 μg/kg CAP.
Milk, whey, cheese and salt solution were sampled during cheese
preparation and ripening.
It was ascertained, that on cheese making 78% of
chloramphenicol, added into initial milk, accumulates in whey,
while 20% in cheese and 2% in salt solution. If milk contains
0.5 μg/kg CAP, then CAP concentration in cheese and whey will
equal 0.8 and 0.45 μg/kg, respectively. Hence, irregular
chloramphenicol distribution occurs in main and by-products,
therewith CAP concentration in cheese is 1.5-2-times higher than
in utilized milk. Thus, even when making cheese from milk
containing CAP level lower than MRPL, there is a possibility to
obtain contaminated cheese.
It was established, that chloramphenicol recovery from
cheese with developed method is ~90%. Also, techniques for CAP
determination in whey and salt solution were elaborated.
Keywords: Mass spectrometry; Liquid chromatography;
Antibiotics;
4 th EucheMs chemistry congress
P - 0 6 1 9
Low teMPerAture of the MethAne CouPLinG
with uv-ACtivAtion in the MeMBrAne
reACtor
n. BASov 1 , i. oreShKin 2 , n. oreKhovA 1 ,
M. erMiLovA 1 , A. yAroSLAvtSev 1
1 A.V.Topchiev Institute of Petrochemical Synthesis RAS,
Laboratory of Catalysis on Membranes, Moscow, Russia
2 A.V.Topchiev Institute of Petrochemical Synthesis RAS,
Laboratory of Metalllorganic Catalysis, Moscow, Russia
The basic methods to produce hydrocarbon C and above
2
from methane is a thermal activation of the CH molecules that
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breaks C-H bonds that often caused an uncontrolled breakup of
these bonds with free carbon formation. To use the ultraviolet
activation allows conducting the process under low temperature,
but because of the reaction reversibility the methane conversion
remains low. The membrane reactor makes to shift equilibrium
possible by hydrogen removing from the reaction space and
therefore to increase the methane conversion.
The experiments were provided under atmospheric pressure
of the pure methane (99.99%) in the temperature interval
200–270°C with a mercury lamp. The membranes in the form of
Pd-Ru alloy tubes (diameter 1 mm, wall thickness 50 mkm, 1 or
1.7 m lengths) were placed inside the quartz glass reactor filled
with CH . Any gas flow inside the tube allowed moving off the
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hydrogen that penetrated through the membrane from the reaction
space outside this tube. The mane products analysed by GC were
propane and ethane with small quantity of the ethylene.
The methane conversion with 1 m tube at 215°C was four
times higher (5.2 %) when hydrogen was removed through a
membrane than without hydrogen removing off at the same
temperature. The highest obtained conversion was 14.3 % at
265°C with hydrogen removing off from the reaction space.
Probable products formation mechanism
CH -> CH · + H·
4 3
CH -> CH : + H 4 2 2
2CH · -> CH -CH 3 3 3
CH : + CH -CH -> CH -CH -CH 2 3 3 3 2 3
2CH : -> CH =CH 2 2 2
2H· -> H2 The methane molecules’ activation by the UV-radiation
allows providing their coupling under comparatively low
temperature that reduces power inputs and a deep
dehydrogenation with free carbon formation. To use a palladium
alloy membrane reactor allows increasing the methane conversion
due to hydrogen removing from the reaction space.
AUGUst 26–30, 2012, PrAGUE, cZEcH rEPUbLIc