硝苯地平在多壁碳纳米管修饰电极上的电化学行为及伏安测定

目的:研究硝苯地平在碳纳米管修饰电极上的电化学行为及测定。方法:制备碳纳米管修饰电极,以此为工作电极,用线性扫描伏安法测定硝苯地平。结果:与裸玻碳电极相比,多壁碳纳米管修饰电极能显著提高硝苯地平的还原峰电流。在优化实验条件下,还原峰电流与硝苯地平浓度在7.5×10~(-8)～2.5×10~(-5)mol·L~(-1)有良好的线性关系,检出限为2.5×10~(-8)mol·L~(-1)。对1.0×10~(-6)mol·L~(-1)硝苯地平溶液平行测定10次的 RSD 为4.6%。结论:该方法简单、快速、灵敏,可用于硝苯地平的药剂分析。     

β-环糊精修饰电极直接测定肾上腺素注射液的含量

目的:研究肾卜腺素(EP)在β-环糊精修饰聚乙酰苯胺玻碳电极(β-CD/PNAANI/GCE)上的电化学行为,建立一种新的测定 EP 的电化学分析方法。方法:用循环伏安法研究 EP 在修饰电极上的氧化还原特性,用差分脉冲伏安法直接测定肾上腺素的含量。结果:该修饰电极能很好地催化 EP,与裸玻碳电极(GCE)相比,还原峰电流增强近30倍。在 pH 7.5磷酸盐缓冲液中,还原峰电流与 EP 的浓度在6.0×10~(-6)～1.0×10~(-4) mol·L~(-1)范围内呈良好的线性关系,其线性回归方程为 I_p=1.68 6.92×10~(-6)C_(EP),相关系数为0.9975,检测限为1.0×10~(-7)mol·L~(-1)。回收率在97.5%～104.5%之间。结论:该方法操作简单,可用于注射液中盐酸肾上腺素含量的测定,结果令人满意。     

活化玻碳电极直接测定注射液多巴胺的含量

目的:研究多巴胺(DA)在活化玻碳电极(AGCE)上的电化学行为,建立一种测定多巴胺(DA)的电化学分析方法。方法:玻碳电极在0.1 mol·L~(-1)磷酸盐缓冲液(pH 7.0)中活化,用循环伏安法研究 DA 在活化玻碳电极上的氧化还原特性,用微分脉冲伏安法直接测定 DA 的含量。结果:DA 在活化玻碳电极上的循环伏安图具有一对灵敏的氧化还原峰,峰电位分别为0.167 V 和0.217 V(vs.SCE)。与裸玻碳电极相比,该电极对 DA 的氧化具有良好的电催化作用。微分脉冲伏安法测定 DA 的氧化峰电流与其浓度在2个区间成正比,分别为1.0×10~(-6)～2.5×10~(-5)～mol·L~(-1)和2.5×10~(-5)～2.5×10~(-4)mol·L~(-1),线性相关系数分别为0.9931和0.9938,检出限5.0×10~(-7)～mol·L~(-1)。抗坏血酸(AA)和尿酸(UA)对 DA 的测定均没有干扰。结论:该方法操作简单方便,重现性较好,用于测定多巴胺注射液中 DA 的含量,结果令人满意。     

线性扫描伏安法测定克拉霉素含量

目的研究克拉霉素(CAM)在多壁碳纳米管修饰玻碳电极上的电化学行为,建立一种直接测定CAM的电化学分析方法。方法采用循环伏安法研究CAM在修饰电极上的电化学行为,以线性扫描伏安法对其含量进行测定。结果在优化实验条件下,氧化峰电流与CAM浓度在5.0×10-7~1.0×10-4mol/L范围呈现良好的线性关系,检出限为1.0×10-7mol/L;对5.0×10-6mol/L CAM溶液平行测定10次的RSD为2.6%。结论该方法简单、快速、灵敏,可用于CAM胶囊的质量分析。     

导电聚合物膜修饰电极用于对乙酰氨基酚和抗坏血酸的同时测定

目的:研究对乙酰氨基酚和抗坏血酸在4-(2-吡啶偶氮)间苯二酚(PAR)导电聚合膜修饰电极上的电化学行为,建立同时测定对乙酰氮基酚和抗坏血酸含量的电化学分析新方法。方法:采用循环伏安法研究对乙酰氨基酚和抗坏血酸在膜修饰电极上的电化学行为,以差示脉冲伏安对二者含量进行测定。结果:聚 PAR 膜修饰电极对对乙酰氨基酚和抗坏血酸有很强电催化作用,明显增强了电极反应的可逆性。在 pH 6.0磷酸盐缓冲液中,对乙酰氨基酚氧化峰电流与其浓度在1.0×10~(-8)～1.5×10~(-5),5×10~(-5)～4×10~(-4)mol·L~(-1)范围内呈良好的线性关系,抗坏血酸氧化峰电流与其浓度在1.0×10~(-6)～3.0×10~(-4)mol·L~(-1)范围内呈良好的线性关系,检出限分别为5.0×10~(-9)mol·L~(-1)和5.0×10~(-7)mol·L~(-1)。结论:该修饰电极可以对对乙酰氨基酚和抗坏血酸进行单独或同时的测定,并用于实际样品维 C 银翘片中对乙酰氨基酚和抗坏血酸的含量检测,结果令人满意。     

多壁碳纳米管修饰电极测定盐酸环丙沙星

目的研究盐酸环丙沙星(CPLX)在多壁碳纳米管修饰玻碳电极上的电化学行为,建立一种直接测定CPLX的电化学分析方法。方法循环伏安法与线性扫描伏安法等电化学方法。结果在优化实验条件下,氧化峰电流与CPLX浓度在1.0×10-7~7.5×10-5mol/L范围呈现良好的线性关系,检出限为3.0×10-8mol/L。对5.0×10-5mol/L     

聚伊文思蓝膜修饰玻碳电极在抗坏血酸共存时测定去甲肾上腺素

目的:研究聚伊文思蓝(Evans Blue)膜修饰玻碳电极对去甲肾上腺素(NE)和抗坏血酸(AA)的电化学行为,建立测定NE 含量的电化学分析新方法。方法:采用循环伏安法研究 NE 和 AA 在聚伊文思蓝膜修饰电极上的电化学行为,以差示脉冲伏安对 NE 的含量进行测定。结果:聚伊文思蓝膜修饰电极对 NE 和 AA 有显著的增敏和电分离作用,氧化峰电位差为282mV。在 pH 5.0的磷酸盐缓冲液中,氧化峰电流与 NE 浓度在5.0×10~(-7)～1.8×10~(-5)mol·L~(-1)范围内呈良好的线性关系,检测限为4.0×10~(-8)mol·L~(-1)。结论:该修饰电极在抗坏血酸共存时可测定 NE,有效消除其他组分对 NE 测定的干扰,已用于实际样品 NE 含量的测定,结果令人满意。     

对乙酰氨基酚在多壁碳纳米管修饰电极上的电化学行为及其测定

目的:研究对乙酰氨基酚(ACOP)在多壁碳纳米管(MWCNTs)修饰电极上的伏安行为,建立测定 ACOP 含量的电化学分析新方法。方法:采用循环伏安法研究 ACOP 在 MWCNTs 修饰电极上的电化学行为及其含量测定方法。结果:MWCNTs 修饰电极对 ACOP 有明显的电催化作用。在 pH 4.8醋酸盐缓冲液中,氧化峰电流与 ACOP 浓度在2.0×10~(-2)～10.0μmol·L~(-1)范围内呈良好的线性关系,检测限为2.0×10~(-3)μmol·L~(-1)。结论:MWCNTs 修饰电极可有效消除制剂中其他组分对 ACOP 测定的干扰,用于实际样品中 ACOP 含量的直接测定,回收率在98.1%～100.3%之间。该方法灵敏度高、检测范围宽,结果令人满意。     

奥硝唑在碳纳米管修饰的玻碳电极上的电化学行为及分析应用

目的:研究奥硝唑在碳纳米管修饰的玻碳电极上的电化学行为及其测定方法。方法:循环伏安法和线性扫描伏安法。结果:在0.2 mol.L-1NH3-NH4Cl缓冲溶液(pH9.0)和1.2 mol.L-1NaCl溶液组成的底液中,奥硝唑在-0.62 V(υs.SCE)处出现一灵敏的还原峰,2.0×10-7～3.0×10-5mol.L-1范围内呈线性关系(r=0.998),检出限为1.5×10-8mol.L-1。并用循环伏安法研究了奥硝唑还原峰的电流性质,发现电极反应是完全不可逆的,并存在一定的吸附性。结论:利用奥硝唑在碳纳米管修饰的玻碳电极上的还原行为建立的分析方法简便灵敏,结果准确可靠,可用于奥硝唑的质量监控及药代动力学研究。     

酒石酸泰乐菌素在多壁碳纳米管修饰电极上的电催化氧化及电化学动力学性质

目的 研究酒石酸泰乐菌素(tylosin tartrate,TT)在多壁碳纳米管修饰玻碳电极(MWCNT/GCE)上的电催化氧化及其电化学动力学性质.方法 用循环伏安法(CV)、线性扫描伏安法(LSV)、计时库仑法(CC)和计时电流法(CA)等多种电化学方法进行研究.结果 在Na2SO4底液中,TT在裸电极上无明显氧化峰,而在MWCNT/GCE上于0.90 V附近出现一不可逆氧化峰.测得TT在MWCNT/GCE上电极反应动力学参数:电荷转移系数α=0.77,扩散系数D=8.18×10~(-5)cm~2/s,电极反应速率常数K_f=2.08×10~(-3)cm/s.结论 MWCNT/GCE对TT具有明显的电催化氧化作用,据此研究结果可建立TT的电化学定量测定方法.     

Toxicological interactions between carbon monoxide and carbon dioxide

Fischer 344 male rats were subjected to 30-min individual or combined exposures of carbon monoxide (CO) and carbon dioxide (CO2). All deaths from CO occurred during the exposures, and the LC50 values were 4600 and 5000 ppm, depending on experimental conditions. Animals exposed to CO2 concentrations ranging from 1.3 to 14.7% for 30 min were neither incapacitated nor fatally injured. The addition of nonlethal concentrations of CO2 (1.7 to 17.3%) to sublethal concentrations of CO (2500 to 4000 ppm) caused deaths of the exposed rats both during and following (up to 24 h) the 30-min exposures. The most toxic combination of these two gases (2500 ppm CO plus 5% CO2) increased the rate of carboxyhemoglobin (COHb) formation 1.5 times that found in rats exposed to 2500 ppm of CO alone. The COHb equilibrium levels were the same. Exposure to both CO and CO2 produced a greater degree of acidosis and a longer recovery time than that observed with either single gas. The results fit a mathematical model indicating a synergistic interaction. Combustion of 11 materials at their LC50 values indicated that CO was probably the primary toxicant in one case and that the combined CO plus CO2 was the cause of the deaths in three other cases. Additional fire gases need to be studied to explain deaths from the other materials.     

Monitoring multiwalled carbon nanotube exposure in carbon nanotube research facility

With the increased production and widespread use of multiwalled carbon nanotubes (MWCNTs), human and environmental exposure to MWCNTs is inevitably increasing. Therefore, this study monitored the possible exposure to MWCNT release in a carbon nanotube research laboratory. To estimate the potential exposure of researchers and evaluate the improvement of the workplace environment after the implementation of protective control measures, personal and area monitoring were conducted in an MWCNT research facility where the researchers handled unrefined materials. The number, composition, and aspect ratio of MWCNTs were measured using scanning transmission electron microscopy with an energy-dispersive x-ray analyzer. The gravimetric concentrations of total dust before any control measures ranged from 0.21 to 0.43 mg/m(3), then decreased to a nondetectable level after implementing the control measures. The number of MWCNTs in the samples obtained from the MWCNT blending laboratory ranged from 172.9 to 193.6 MWCNTs/cc before the control measures, and decreased to 0.018-0.05 MWCNTs/cc after the protective improvements. The real-time monitoring of aerosol particles provided a signature of the MWCNTs released from the blending equipment in laboratory C. In particular, the number size response of an aerodynamic particle sizer with a relatively high concentration in the range of 2 to 3 microm in aerodynamic diameter revealed the evidence of MWCNT exposure. The black carbon mass concentration also increased significantly during the MWCNT release process. Therefore, the present study suggests that the conventional industrial hygiene measures can significantly reduce exposure to airborne MWCNTs and other particulate materials in a nano research facility.     

杨梅酮在碳纳米管上修饰电极上的电化学性质研究

目的：制备了多壁碳纳米管修饰玻碳电极（MWNTs／GC）,并研究了杨梅酮在MWNTs／GC上的电化学性质。方法：采用循环伏安法对杨梅酮的浓度进行测定。结果：氧化还原峰电流与杨梅酮的浓度呈线性关系。结论：多壁碳纳米管对杨梅酮有良好的催化活性,MWNTs／GC对于测定杨梅酮呈现良好的响应特性和较高的洲定灵敏度,该传感器应用于杨梅酮的分析。     

Hemotoxicity of carbon nanotubes

Carbon nanotubes may enter into the bloodstream and interact with blood components indirectly via translocation following unintended exposure or directly after an intended administration for biomedical purposes. Once introduced into systemic circulation, nanotubes will encounter various proteins, biomolecules or cells which have specific roles in the homeostasis of the circulatory system. It is therefore essential to determine whether those interactions will lead to adverse effects or not. Advances in the understanding of how carbon nanotubes interact with blood proteins, the complement system, red blood cells and the hemostatic system are reviewed in this article. While many studies on carbon nanotube health risk assessment and their biomedical applications have appeared in the last few years, reports on the hemocompatibility of these nanomaterials remain surprisingly limited. Yet, defining the hemotoxicological profile is a mandatory step toward the development of clinically-relevant medications or contrast agents based on carbon nanotubes.     

Effect of ethanol on carbon tetrachloride levels and hepatotoxicity after acute carbon tetrachloride poisoning

To study the effect of an acute dose of ethanol on carbon tetrachloride (CCl₄) concentration and hepatotoxicity, female rats received ethanol (2.5 ml/kg body wt.) either intragastrically or intraperitoneally following intragastric administration of CCl₄ (1.5 ml/kg body wt.). Three hours after acute CCl₄ intoxication there was a striking increase in CCl₄ concentration in animals treated simultaneously with ethanol intragastrically compared to those receiving ethanol intraperitoneally. This increase was significant (P<0.05) and amounted to 211% for blood, 236% for liver and 405% for fat tissue, whereas animals treated with CCl₄ alone showed CCl₄ concentrations in the range between the two other experimental groups. Serum activities of glutamate oxalacetate transaminase, glutamate pyruvate transaminase and glutamate dehydrogenase were found to be considerably higher in animals treated with the combination of CCl₄ and ethanol when compared to those receiving CCl₄ alone, showing that ethanol given intraperitoneally or intragastrically enhances CCl₄ hepatotoxicity. Since the intraperitoneal administration of ethanol led to a reduction rather than an increase in CCl₄ concentration in the early phase of intoxication, additional mechanisms independent of actual levels of CCl₄, such as direct effects of ethanol on the CCl₄ metabolizing enzyme of the membrane of the endoplasmic reticulum, have to be implicated in the pathogenesis of the potentiation of CCl₄ hepatotoxicity by ethanol.     

Voltammetric determination of promethazine hydrochloride at a multi-wall carbon nanotube modified glassy carbon electrode

A simple and sensitive method is described for voltammetric determination of promethazine hydrochloride (PMZ), a widely used phenothiazine drug, based on its electrochemical oxidation at a multi-wall carbon nanotube (MWCNT) modified glassy carbon electrode (GCE). Compared with bare GCE, the MWCNT-modified GCE exhibited excellent enhancement effect on the electrochemical oxidation of PMZ. PMZ yielded two anodic peaks at about 0.61 V and 0.78 V, and the peak at 0.61 V was applied to the determination. Under optimized conditions, the anodic peak current was linear to the concentration of PMZ in the range from 5.0 × 10(-8) to 4.0 × 10(-4) M with the detection limit of 1.0 × 10(-8) M. The relative standard deviation (RSD) was 2.28% for 8.0 × 10(-6) M PMZ (n = 10). To further validate its possible application, the proposed method was successfully used for the quantification of PMZ in pharmaceutical formulations and biological fluids with satisfactory results.     

Determinants of carbon nanotube toxicity

In the last few years questions have been raised regarding the potential toxicity of carbon nanotubes (CNTs) to humans and environment. It is believed that the physico-chemical characteristics of these materials are key determinants of CNT interaction with living organisms, and hence determine their toxicity. As for other nanomaterials, the most important of these characteristics are the length, diameter, surface area, tendency to agglomerate, bio-durability, presence and nature of catalyst residues as well as chemical functionalization of the CNT. This review highlights the recent advancements in the understanding of the CNT properties which are essential in determining CNT toxicity. Hence the focus is on CNT dimensions, surface properties, bio-durability and corona formation as these fields have evolved greatly in recent years.