Surface‐enhanced Raman scattering (SERS) spectra of chloramphenicol in Ag colloids prepared by microwave heating method

Ag colloids were prepared by the microwave heating method. The UV‐visible spectrum and the transmission electron microscopy (TEM) were employed to characterize the Ag colloids. The surface‐enhanced Raman scattering (SERS) spectra of chloramphenicol (CAP) in Ag colloids were successfully recorded. The Raman spectra of CAP were recorded with good concordance comparing to the theoretical results calculated by the Gaussian'98 program. CAP molecules on the Ag surface are oriented tilted to the particle surface via C20‐O23, N‐O13, and N‐O23, which played an important role in the SERS effect. Copyright © 2009 John Wiley & Sons, Ltd.     

Tuning Selectivity and Sensitivity of Mixed‐polymeric Tetraruthenated Metalloporphyrins Modified Electrodes as Voltammetric Sensors of Chloramphenicol

Mixed Ni?Co tetraruthenated porphyrin films were successfully electropolymerized on glassy carbon electrodes in alkaline solutions (pH=13) of NiTRP and CoTRP, giving excellent electrocatalytic responses for determination of the antibiotic drug chloramphenicol. Electrodes with four different compositions were obtained by varying the ratio of NiTRP and CoTRP in the deposition solution. For the characterization of these materials, SEM, ICP‐MS, EIS and CV were explored. The porphyrin modified glassy carbon electrodes presented two oxidation peaks for chloramphenicol (except for Ni‐25). The potential shifted to lower values as the percentage of CoTRP increased decreasing its oxidation potential in more than 200 mV for Ni‐50 as compared to Ni‐100. Interestingly, the materials with cobalt content larger than 50 % did not show the typical catalytic response of the Ni^IIIOOH species, but rather showed an increase in current at potentials larger than 0.4 V, demonstrating the key role played by nickel in this type of materials. The composition of polymeric mixed porphyrin materials influenced the oxidation current response of both redox waves, resulting in different sensitivities on the calibration curves.     

Development of quantitative HPTLC-densitometry methods following a model approach for transfer of TLC screening methods for pharmaceutical products of atenolol,chloramphenicol, furosemide,glibenclamide, penicillin V potassium,and praziquantel

Transfer of six thin-layer chromatography (TLC) Global Pharma Health Fund E.V. Minilab manual protocols for detecting fake drugs in pharmaceutical products to quantitative high-performance TLC (HPTLC)-densitometry methods was performed following a previously published model process. The developed and validated methods for tablets or capsules containing atenolol, chloramphenicol, furosemide, glibenclamide, penicillin V potassium, and praziquantel involved use of a limited list of inexpensive, relatively nontoxic, readily available solvents and other reagents; silica gel 60?F₂₅₄ plates; automated bandwise sample and standard solution application; ascending mobile phase development of plates in a chamber; and automated slit scanning densitometry for detection, identification, and quantification. Validation data for methods developed in an early version of the transfer model process that did not include standard addition validation are reported for pharmaceutical products containing amitriptyline HCl, amodiaquine, diphenhydramine HCl, and mebendazole.     

对虾中氯霉素残留的分析方法研究

用液相色谱-质谱法定量检测对虾中微量的氯霉素残留。采用乙酸乙酯超声提取对虾组织中的氯霉素残留,以甲醇为流动相,选择m／x321／152为氯霉素的检测离子对,用多反应监测(MRM)技术测定。氯霉素流出液相色谱的时间在1．5min以内;线性范围是0．28-28．0μg／L;线性相关系数为0．99991。对虾中氯霉素的定量检测下限是0．07μg／kg,平均回收率在89％以上。该方法快速、灵敏,定量范围宽,检验结果准确可靠,应用性强。     

Structural modification of bacterial cellulose

The microfibrillar nature of bacterial cellulose produced by Acetobacter was modified by various chemical reagents in a culture medium. The chemical reagents included antibiotics to inhibit cell division or certain protein synthesis, and reducing reagents that induce reductive cleavage of disulfide bonds in proteins. Among the reagents tested, nalidixic acid and chloramphenicol induced elongation of bacteria, resulting in the formation of wider cellulose ribbons or aggregates of ribbons. The Young's modulus of the sheets made from such cellulose increased, while dithiothreitol, which produced ribbons having only 45% of the width of the control, produced sheets with undiminished Young's modulus. Although further study is necessary to clarify the effect of such modifications, nalidixic acid and chloramphenicol produced a bacterial cellulose with superior mechanical properties.     

基于分子印迹膜的检测牛奶中琥珀酸氯霉素残留传感方法的研究

采用光聚合法在一次性丝网印刷电极上制备琥珀酸氯霉素分子印迹膜,然后将丝网印刷电极通过电极插口与电化学分析装置相连接,组装成检测琥珀酸氯霉素残留的电化学传感仪.使用与传感装置相连接的记录仪记录响应的结果.采用本传感仪建立了检测氯霉素的标准曲线并测试了实际牛奶样品中氯霉素含量.电镜学观察表明,与非印迹膜相比,在印迹膜表面形成大量直径约为100 nm的印迹微孔.本传感仪装置检测琥珀酸氯霉素具有很高的灵敏度和特异性,检出限为2×10-9 mol/L,检测线性范围为1×10-8～1.2×10-5 mol/L,基于牛奶样品的检测回收率介于93.5%～95.5%之间.     

Covalently bonded aptamer‐functionalised magnetic mesoporous carbon for high‐efficiency chloramphenicol detection

A novel aptamer‐modified magnetic mesoporous carbon was prepared to develop a specific and sensitive magnetic solid‐phase extraction method through combination with ultra‐high performance liquid chromatography‐tandem mass spectrometry for the analysis chloramphenicol in complex samples. More specifically, the chloramphenicol aptamer‐modified Mg/Al layered double hydroxide magnetic mesoporous carbon was employed as a novel magnetic solid‐phase extraction sorbent for analyte enrichment and sample clean‐up. The extraction solvent, extraction time, desorption solvent, and desorption time were investigated. It was found that the mesoporous structure and aptamer‐based affinity interactions resulted in acceptable selective recognition and a good chemical stability toward trace amounts of chloramphenicol. Upon combination with the ultra‐high performance liquid chromatography‐tandem mass spectrometry technique, a specific and sensitive recognition method was developed with a low limit of detection (0.94 pmol/L, S/N = 3) for chloramphenicol analysis. The developed method was successfully employed for the determination of chloramphenicol in complex serum, milk powders, fish and chicken samples, giving recoveries of 87.0‐107% with relative standard deviations of 3.1‐9.7%.     

分散液相微萃取/液相色谱串联质谱法快速测定猪尿中的盐酸克伦特罗与氯霉素

采用分散液相微萃取净化技术,建立了快速测定猪尿中盐酸克伦特罗和氯霉素残留的高效液相色谱-串联质谱分析方法.取5 mL猪尿样品,分别加入5 ngD9-盐酸克伦特罗和D5-氯霉素内标,调节pH至10.0,加入10％ NaC1,经250 μL三氯甲烷和750 μL异丙醇分散萃取后离心,转移下层沉淀,氮吹后以甲醇水溶液定容,采...     

阳离子表面活性剂对电化学法测试牛奶中氯霉素残留量的影响

为探索用电化学方法检测生物样品中氯霉素残留的高灵敏度技术,本实验研究了阳离子表面活性剂十六烷基三甲基溴化铵(CTMAB)对氯霉素在玻碳电极上伏安行为的影响,实验结果表明,以0.02 mol/L高氯酸为支持电解质,在0.40~-0.60 V的范围内进行伏安扫描时,2×10-5mol/L CTMAB能显著提高氯霉素在-0.41 V处的还原峰电流。利用这种改进的电化学方法检测氯霉素的线性范围为0.0026~8 mg/L,检出限达到0.83μg/L。研究了缓冲液种类及其酸碱度及其它表面离子活性剂等对测试氯霉素的影响。