Electrochemiluminescence

Slide 1: 

Franklin Ifeanyichukwu Uba CHEM 7750 - Separation science

Slide 2: 

Objective To develop a new and sensitive CE-ECL method for the analysis of Enrofloxacin and Ciprofloxacin in milk samples

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CE Principle http://www.authorstream.com/Presentation/abikesh086-174281-capillary-electrophoresis-education-ppt-powerpoint/

Electro-chemiluminescence : 

Electro-chemiluminescence Excitation results from electrochemical reaction Widely used in clinical analytes Ru(bpy)32+; emits photons-620nm Ru(bpy)32+ + e- Ru(bpy)3+ Ru(bpy)32+ - e- Ru(bpy)3+ + Ru(bpy)33+ Ru(bpy)33+ Ru(bpy)32+* Ru(bpy)32+ + hν Ru(bpy)32+* + Ru(bpy)32+ Alan lee, et.al. Proc. Of SPIE Vol . 5331, 2004.

Analyte - metabolism : 

Analyte - metabolism Ciprofloxacin (CIP) Enrofloxacin (ENR) N - Alkylation N - dealkylation Quinolones – as synthetic antibiotic ENR - treatment of respiratory and Gastro-intestinal infection CIP – active metabolite CIP and ENR amine stimulants MRL values for ENR plus CIP in food stuffs (animal origin) in the range 100–300 μg/kg

ECL Principle : 

ECL Principle e- e- Electrode (CIP or ENR)+. (CIP or ENR) H+ (CIP or ENR). Ru(bpy)32+ Ru(bpy)33+ Ru(bpy)32+* Ru(bpy)32+ λ = 620 nm hν (CIP or ENR)

Experiment : 

Experiment Solid phase extraction Electro-kinetic injection – HV 10 kV, 20 s, RT Uncoated Fused-Silica – 50cm, 50μm, 360μm Separation voltage 14 kV 15 mM running buffer MPI-A CE-ECL detector – 3-electrode system Working electrode; Pt wire (300-μm dia.) Reference electrode; Ag/AgCl (KCl saturated) Counter electrode; Pt wire PMT to capture photons (800 V)

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Effect of Detection potential

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Effect of running buffer pH a = pH 7 b = pH 7.5 c = pH 8 d = pH 8.5 e = pH 9

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Injection time - ECL intensity and Resolution a = CIP b = ENR c = Rs

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Linearity Optimum conditions

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Milk Samples a = Blank Milk b = Blank milk spiked; 15μg/kg CIP and 15μg/kg ENR;

Conclusions : 

Conclusions ECL detector is sensitive, simple and cheap detection with a low background noise Detection limits of ENR (10 ng/ml) and CIP (15 ng/ml) were achieved

Acknowledgments : 

Acknowledgments Dr S.D Gilman CHEM 7750 Colleagues