“I grew up on antibiotics. Every ailment - sore throats, earaches, flus - warranted a trip to the...
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Transcript of “I grew up on antibiotics. Every ailment - sore throats, earaches, flus - warranted a trip to the...
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“I grew up on antibiotics. Every ailment - sore throats, earaches, flus - warranted a trip to the doctor and in most cases some kind of prescription”
“Am crescut cu antibiotice. Orice indispoziţie – dureri de gât, dureri de urechi, răceală – îmi garanta o vizită la doctor şi în cele mai multe cazuri
prescrierea unei reţete”
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• Cephalosporins - one of the most important and probably the most frequently used antibiotics in the world - in terms of the number of compounds currently on the market as well as of their use for the treatment of infectious diseases.
Introduction
• Cephalosporins: β-lactam antibiotic
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Capillary electrophoresis (CE)
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N
S
R'
COOH
O
R-CO-NH
Aim of study• study of the electrophoretic behaviour of cephalosporins from different different generations having different structural characteristics using several background electrolytes at variuos pH.
• simultaneos separation of cephalosporins from complex mixtures.
• optimization of the electrophoretic parameters and analytical conditions of the separation – increased resolution and short analysis time.
Studied cephalosporins:
- 1st generation cephalosporins: cefalexin, cefadroxil, cefaclor, cefazolin;
- 2nd generation cephalosporins: cefuroxim, cefoxitin;
- 3rd generation cephalosporns: cefoperazone, cefotaxime, ceftazidim, ceftriaxon;
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Studied cephalosporins
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• Reagents: sodium tetraborate, disodium hydrogenophosphate, sodium dihydrogenophosphate, phosphoric acid, sodium hydroxide, methanol (Merck, Germany). Purified water - Milli-Q water purification system.
• Cephalosporins: cefalexin monohydrate, cefaclor monohydrate were obtained from Sandoz (Târgu-Mureş, România); cefadroxil monohydrate, ceftriaxon sodium, cefotaxime sodium, cefazolin sodium, cefoxitin sodium from Antibiotice (Iaşi, România); cefuroxim sodium from Medochemie (Cyprus); ceftazidim pentahydrate, cefoperazone sodium from Glaxo (Bucureşti, România).
• CE system: Agilent 6100 CE - DAD detection; software: Chemstation.• Capillary: polyimide-coated fused silica-capillaries of 48 cm (effective
length: 40 cm) x 50 μm I.D. (Agilent).• For the identification of the individual peaks, the UV spectrum of each
cephalosporin was recorded previously – detection at 210, 230, 250 nm.• “Standard” electrophoretic conditions: voltage + 25kV, temperature
25 0C, injection pressure/time: 50 mbar/3 sec., injection at the anodic end of the capillary.
• Stock solutions: 100 μg/ml in methanol – dilution.
Materials and methods
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Electrophoretic behavior of cephalosporins at pH - 7
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Electrophoretic parameters of cephalosporins at pH - 7
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Cephalosporins separation at pH - 7
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Electrophoretic behavior of cephalosporins at pH – 9.3
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Electrophoretic parameters of cephalosporins at pH – 9.3
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Cephalosporins separation at pH – 9.3
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Electrophoretic behavior of cephalosporins at pH - 5
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Cephalosporins separation by CZE
Optimum BGE: 25 mM disodium hydrogenophosphate – 25 mM sodium didydrogenophosphate mixture - pH – 7
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Optimization of analytical conditions - Voltage
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Optimization of analytical conditions - Temperature
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Optimization of analytical conditions – Injection parameters
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Analytical parameters
n = 6; c = 25 µg/ml
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Analytical parameters
n = 6; c = 5 - 100 µg/ml
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• Electrophoretic mobilities and behavior of cephalosporins – strongly related to structural characteristics.
• ECZ - can be used for the identification and determination of cephalosporins in formulated pharmaceutical products and for separations from complex mixtures.
• The use of an appropriate electrolyte at the right pH , or a combination of electrolytes enables the identification and separation of the studied substances from complex mixtures
• Optimum separation conditions: BGE - 25 mM NaH2PO4+ 25 mM Na2HPO4, pH=7, voltage: 25 kV, temperature: 25ºC, injection pressure/time: 50mbar/3sec, detection at 210 and 250 nm.
Conclusions
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The first rule of antibiotics is try not to use them, and the second rule is try not to use too many of them.
Prima regulă a terapiei cu antibiotice este să încerci să nu le utilizezi, iar a doua regulă este să nu le utilizezi prea des
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