An overview of analytical methodologies for the determination of antibiotics in environmental waters

The widespread occurrence of antibiotics as contaminants in the aquatic environment has increased attention in the last years. The concern over the release of antibiotics into the environment is related primarily to the potential for the development of antimicrobial resistance among microorganisms. This article presents an overview of analytical methodologies for the determination of quinolone (Qs) and fluoroquinolone (FQs), macrolide (MLs), tetracycline (TCs), sulfonamide (SAs) antibiotics and trimethoprim (TMP) in different environmental waters. The analysis of these antibiotics has usually been carried out by high-performance liquid chromatography (HPLC) coupled to mass spectrometry (MS) or tandem mass spectrometry (MS/MS) and to a lesser extent by ultraviolet (UV) or fluorescence detection (FD). A very important step before LC analysis is sample preparation and extraction leading to elimination of interferences and prevention of matrix effect and preconcentration of target analytes.     

恩诺沙星与脱氧核糖核酸的相互作用

采用紫外光谱和荧光光谱法,在生理条件下(pH=7.4)对恩诺沙星(ENR)与小牛胸腺脱氧核糖核酸(ct-DNA)的作用方式进行了研究。证实了恩诺沙星通过嵌插方式和静电结合方式与DNA发生相互作用。实验表明,DNA能猝灭恩诺沙星的内源性荧光,DNA与恩诺沙星的相互作用为静态猝灭过程,其结合常数为2.73×105L.mol-1,结合位点数为1.12。     

恩诺沙星与牛血清白蛋白的相互作用

恩诺沙星与牛血清白蛋白的相互作用;恩诺沙星;牛血清白蛋白;荧光猝灭     

反相高效液相色谱法同时测定4种氟喹诺酮类药物在鸡可食性组织中的残留

建立了一种可同时测定鸡可食性组织中环丙沙星、达氟沙星、恩诺沙星及沙拉沙星等多种残留的反相高效液相色谱 -荧光分析法。鸡的肌肉、皮和脂、肝、肾等4种组织经不同pH值的磷酸二氢钾缓冲溶液匀浆提取,上清液通过C18固相萃 取柱净化,以流动相洗脱。洗脱液经液相色谱分离后,用荧光检测器进行检测(激发波长280 nm, 发射波长450 nm),外标 法定量。对鸡的4种组织进行添加回收率测定,结果显示方法在添加水平为20~300 μg/kg时药物的回收率约为53.9%～93.4%,批间回收率测定值的相对标准偏差低于23%;环丙沙星、恩诺沙星、沙拉沙星 的定量检出限为20 μg/kg,达氟沙星为4μg/kg。方法简单、快速,能满足常规兽药残留检测的需要。     

光谱法结合分子模拟分析乳铁蛋白与药物恩诺沙星的互作分子机理

利用光谱实验结合计算机模拟技术研究了药物恩诺沙星(Enrofloxacin,EFLX)与牛乳铁蛋白(Bovine lactoferrin,BLF)的相互作用机理。测定反应体系的结合参数、能量转移参数及热力学函数,考察EFLX对BLF分子构象的影响,并模拟EFLX-BLF结合反应的分子模型。结果表明,药物分子与牛乳铁蛋白的相互作用表现为动态结合过程,结合强度适中,EFLX与BLF分子的结合距离r值较小,说明发生了能量转移现象。EFLX影响BLF的结构域微区构象,降低结合位域的疏水性。荧光相图技术解析出EFLX与BLF反应构象型态的变迁为"二态模型"。EFLX-BLF的热力学参数表明两者间是以氢键和范德华力为主的分子间作用。分子建模结果显示,EFLX与BLF的相互作用主要为氢键和范德华力,兼有疏水作用力。计算机分子模拟与实验测试获得了一致性结果。     

反相离子对高效液相色谱法测定动物血浆中的恩诺沙星

1　前言恩诺沙星 ( enrofloxacin,ERFX)系全合成新一代喹诺酮类抗菌药、具有高效、广谱 ,耐药菌极少、副作用小等优点 ,是当今世界动物用最佳的抗感染类药物之一[1～ 5] 。Kung等[3] 认为 ERFX抗菌是其在体内代谢为环丙沙星 ( ciprofloxacin,CPFX)而发挥作用的。有关分析 ERFX文献较少[2 ] 。为了研究 ERFX的药代动力学 ,本文建立了 ERFX测定的反相离子对 HPLC分析方法。2　实验部分2 .1　仪器与试剂日本岛津 LC-6A高效液相色谱系统 ,具CTO-6A柱箱、SCL -6A系统控制器、SPD-6AV紫外 -可见检测器和 C-R3 A色谱数据处理机…     

Determination of Ciprofloxacin,Enrofloxacin, and Marbofloxacin in Bovine Urine,Serum, and Milk by Microextraction by a Packed Sorbent Coupled to Ultra-High Performance Liquid Chromatography

This article reports new, easy, and rapid microextraction by packed sorbent (MEPS)–ultra high performance liquid chromatography with photodiode array detection for the simultaneous determination in bovine urine, serum, and milk of three antibiotics belonging to the class of the fluoroquinolones, namely ciprofloxacin, enrofloxacin, and marbofloxacin, approved for veterinary and human use (ciprofloxacin). The chromatographic separation of the analytes and all aspects influencing the MEPS performance were optimized for the extraction from the considered biological samples. The optimized procedure required simple sample pretreatment, a short (<8?min) isocratic elution, and provided sufficient sensitivity for the determination of the analytes at trace levels in compliance with current legislation. Limits of quantitation were in the range from 0.002 (ciprofloxacin, urine) to 0.048?μg/mL (enrofloxacin, milk). Recoveries from 79% (enrofloxacin, milk) to 88% (ciprofloxacin, urine/serum) were obtained on spiked samples. The within-day (n?=?6) and between-day (n?=?6 over 3?days) relative standard deviation percentages in bovine urine, serum, and milk samples ranged from 2.2 (ciprofloxacin, urine) to 2.5 (enrofloxacin, serum) and from 3.1 (ciprofloxacin, urine) to 3.7 (enrofloxacin, milk), respectively, and were not concentration dependent. To the best of our knowledge, this is the first study describing a fast and simple method for the determination of fluoroquinolones in bovine biological samples.     

恩诺沙星棕榈酸盐的合成和谱学研究

鉴于恩诺沙星属两性化合物,可与酸或碱作用形成酸式盐或碱性盐,为改善氟喹诺酮类兽医专用抗菌药恩诺沙星的口感、减轻苦味,合成了恩诺沙星棕榈酸盐.采用红外光谱法对恩诺沙星棕榈酸盐的主要官能团进行了鉴定,采用核磁共振氢谱及质谱对其分子结构进行了确认。相关研究结果可望为氟喹诺酮类兽医专用抗菌药的开发提供依据.     

恩诺沙星粉中未知添加物的确证

应用非靶向分析技术,筛查、分析和确证恩诺沙星粉(水产用)中的非法添加物。分别制备甲酸酸化、碳酸钠碱化的恩诺沙星粉供试品溶液,经超高效液相色谱-二极管阵列检测器(UPLC-PDA)检测初筛,获取未知物色谱图。应用超高效液相色谱-飞行时间高分辨质谱(UPLC-TOF-HRMS),在正、负离子模式下对酸化、碱化样液进一步检测,获得未知物母离子和二级特征碎片的精确质荷比、同位素信息,并应用SCIEX OS软件进行分析推导。最后取疑似化合物对照品进行确证研究。UPLC-PDA初筛结果显示:酸化样液在1.870 min、5.122 min,碱化样液在5.122 min,均发现高响应未知色谱峰。对吸收波长和峰面积进行分析,推测含2个未知物,且未知物1(1.870 min)与未知物2(5.122 min)在酸性/碱性条件下可能发生转换。SCIEX OS软件分析推导结果显示:未知物2,母离子分子式拟合为C₁₁H₈O₂,二级碎片结构解析含1个苯环、2个羰基和1个通过成环连接的丙烯结构,推测为甲萘醌;未知物1的分子离子峰为C₁₁H₉O₅S^-,二级碎片仅采集到HSO₃^-,丢失部分与未知物2一致,结合甲萘醌常见衍生物类型,推测为亚硫酸氢钠甲萘醌。取甲萘醌、亚硫酸氢钠甲萘醌对照品进行对比研究,UPLC-PDA检测结果显示:未知物1与亚硫酸氢钠甲萘醌、未知物2与甲萘醌,保留时间和紫外光谱一致;向供试溶液中添加对照品溶液后检测,未知物为单一峰。UPLC-TOF-HRMS检测发现:未知物1与亚硫酸氢钠甲萘醌保留时间一致,一级质谱质量偏差为1.0×10^-6,二级谱库匹配度为100%;未知物2与甲萘醌保留时间一致,一级质谱质量偏差为0.6×10^-6,二级谱库匹配度为99.7%。未知物1和2的结构得以确证。亚硫酸氢钠甲萘醌可止血,与恩诺沙星治疗败血症的适应证相应,佐证试验结果。随着对兽药非法添加行为的严格监管和严厉打击,非法添加物和添加手段愈发隐蔽,常规靶向分析难以满足监控需求。该文详述的使用UPLC-PDA结合UPLC-TOF-HRMS对未知物进行非靶向分析的技术,可为药品、食品、保健品、化妆品及农药等产品中非法添加物的筛查和确证提供思路和技术参考。     

Malonylchitosan Microspheres as a Matrix for Oral Enrofloxacin Delivery

Summary: The purpose of this study was to produce malonylchitosan microspheres to be used as a pH sensitive matrix for the controlled delivery of drugs. Chitosan microspheres were obtained by the coacervation–phase separation method. The microspheres were then treated with malonic acid to obtain amidified chitosan microspheres. The resulting malonylchitosan microspheres were characterized by means of elemental analysis (CHN), infrared spectroscopy, conductometric titration and scanning electron microscopy (SEM). The data obtained from infrared spectroscopy, elemental analysis and conductometric titration of amino groups were consistent with the N-substitution of malonyl groups in the chitosan microspheres. In vivo studies for controlled delivery of enrofloxacin were performed in male Wistar rats and the results indicated increase and prolonged blood levels with delayed peak and improved bioavailability for malonylchitosan microspheres compared to commercial tablets.