Determination Of Oxytetracycline By Electrochemical Method

Oxytetracycline (OTC) is tetracycline, which could be used for treating infections caused by various gram-positive and gram-negative bacteria as broad spectrum topical antibiotic. Owing to the anti-inflammatory of OTC, it was often illegally abused in the animal feed and food. Rapid electrochemical determination of OTC was investigated in the work, which was helpful to supervise the quality of OTC effectively for functional department. The main research results are as follows:The system of electroanalytical chemistry for OTC was established,which was detected by differential pulse stripping voltammetry, and glassy carbon electrode modified with multi-walled carbon nanotube (MWNT) was used as the working electrode, sodium citrate-hydrochloric acid buffer solution(0.1mol/L,pH=2.0) as electrolyte. The stripping peak potential of OTC was -1.024V(vs.SCE) on the working electrode, the linear range of determination of OTC was 0.1～1μg/mL, and the linear equation was expressed as I=4.7836C+0.6153, r=0.9973 ; besides, the detection limit was 0.5μg/mL, and the RSD was 3.8% for OTC at 0.5μg/mL through 10 parallel determinations. Therefore, this method could used to determine OTC in OTC tablet rapidly, and the precisions and accuracies all accorded with requirements of determination.In addition, a new method about determination of OTC residues in milk was investigated. Under the optimum conditions (square amplitude: 25mV, frequency: 10Hz, potentiometer incremental: 0.005mV, sedimentary: 80s), it was found that the oxidation peak current was linear with the concentration of OTC between 5.0×10⁽-7mol/L to 5.0×10^-5mol/L, the linear regression equation was I(μA)=0.4995+1.119×10⁷ C(mol/L), the correlation coefficient r=0.9988, and the detection limit (3S/N)was 1.0×10^-8mol/L. Besides, the influence of the common metal ions(Ca²⁺,Pb²⁺,Na+,Mg²⁺,Al³⁺,Cd²⁺,K⁺,Cl^-,SO₄^2-,NO₃^-)and coexistence of organic compounds (uric acid, ascorbic acid, dopamine, vitamin E) in the milk was analyzed ,and the results showed that there were no interference phenomenon in the experiment.In summary, the electrochemical analysis can be used to detect antibiotic residues in food, and the method is fast, sensitive, time-saving, simple etc.