Amperometric determination of 6-mercaptopurine on functionalized multi-wall carbon nanotubes modified electrode by liquid chromatography coupled with microdialysis and its application to pharmacokinetics in rabbit

In this paper, multi-wall carbon nanotubes fuctionalized with carboxylic groups modified electrode (MWNT-COOH CME) was fabricated. This chemically modified electrode (CME) can be used as the working electrode in the liquid chromatography for the determination of 6-mercaptopurine (6-MP). The results indicate that the CME exhibits efficiently electrocatalytic oxidation for 6-MP with relatively high sensitivity, stability and long-life. The peak currents of 6-MP are linear to its concentrations ranging from 4.0×10⁻⁷ to 1.0×10⁻⁴ mol l⁻¹ with the calculated detection limit (S/N=3) of 2.0×10⁻⁷ mol l⁻¹. Coupled with microdialysis, the method has been successfully applied to the pharmacokinetic study of 6-MP in rabbit blood. This method provides a fast, sensible and simple technique for the pharmacokinetic study of 6-MP in vivo.     

A dual-electrode approach for highly selective detection of glucose based on diffusion layer theory: experiments and simulation

A dual-electrode configuration for the highly selective detection of glucose in the diffusion layer of the substrate electrode is presented. In this approach, a glassy carbon electrode (GCE, substrate) modified with a conductive layer of glucose oxidase/Nafion/graphite (GNG) was used to create an interference-free region in its diffusion layer by electrochemical depletion of interfering electroactive species. A Pt microelectrode (tip, 5 microm in radius) was located in the diffusion layer of the GNG-modified GCE (GNG-G) with the help of scanning electrochemical microscopy. Consequently, the tip of the electrode could sense glucose selectively by detecting the amount of hydrogen peroxide (H2O2) formed from the oxidization of glucose on the glucose oxidase layer. The influences of parameters, including tip-substrate distance, substrate potential, and electrolyzing time, on the interference-removing efficiency of this dual-electrode approach have been investigated systematically. When the electrolyzing time was 30 s, the tip-substrate distance was 1.8 a (9.0 microm) (where a is the radius of the tip electrode), the potentials of the tip and substrate electrodes were 0.7 V and 0.4 V, respectively, and a mixture of ascorbic acid (0.3 mM), uric acid (0.3 mM), and 4-acetaminophen (0.3 mM) had no influence on the glucose detection. In addition, the current-time responses of the tip electrode at different tip-substrate distances in a solution containing interfering species were numerically simulated. The results from the simulation are in good agreement with the experimental data. This research provides a concept of detection in the diffusion layer of a substrate electrode, as an interference-free region, for developing novel microelectrochemical devices.     

Concentration profiles of cocaine, pyrolytic methyl ecgonidine and thirteen metabolites in human blood and urine: determination by gas chromatography-mass spectrometry

When cocaine is smoked, a pyrolytic product, methyl ecgonidine (anhydroecgonine methyl ester), is also consumed with the cocaine. The amount of methyl ecgonidine formed depends on the pyrolytic conditions and composition of the illicit cocaine. This procedure describes detection of cocaine and 10 metabolites--cocaethylene, nor-cocaine, nor-cocaethylene, methyl ecgonine, ethyl ecgonine, benzoylecgonine, nor-benzoylecgonine, m-hydroxybenzoylecgonine, p-hydroxybenzoylecgonine and ecgonine--in blood and urine. In addition, the detection of pyrolytic methyl ecgonidine and three metabolites--ecgonidine (anhydroecgonine), ethyl ecgonidine (anhydroecgonine ethyl ester) and nor-ecgonidine (nor-anhydroecgonine)--are included. The newly described metabolites, ethyl ecgonidine and nor-ecgonidine, were synthesized and characterized by gas chromatography-mass spectrometry (GC-MS). All 15 compounds were extracted from 3 mL of blood or urine by solid-phase extraction and identified by a GC-MS method. The overall recoveries were 49% for methyl ecgonine, 35% for ethyl ecgonine, 29% for ecgonine and more than 83% for all other drugs. The limits of detection were between 0.5 and 4.0 ng/mL except for ecgonine, which was 16 ng/mL. Linearity for each analyte was established and in all cases correlation coefficients were 0.9985-1.0000. The procedure was applied to examine the concentration profiles of analytes of interest in post-mortem (PM) blood and urine, and in urine collected from living individuals (LV). These specimens previously were shown to be positive for the cocaine metabolite, benzoylecgonine. Ecgonidine, the major metabolite of methyl ecgonidine, was present in 77% of PM and 88% of the LV specimens, indicating smoking as the major route of cocaine administration. The new pyrolytic metabolites, ethyl ecgonidine and nor-ecgonidine, were present in smaller amounts. The urine concentrations of nor-ecgonidine were 0-163 ng/mL in LV and 0-75 ng/mL in PM specimens. Ethyl ecgonidine was found only in PM urine at concentrations 0-39 ng/mL. Ethanol-related cocaine metabolites, ethyl ecgonine or cocaethylene, were present in 69% of PM and 53% of cocaine-positive LV specimens, implying alcohol consumption with cocaine use. The four major metabolites of cocaine--benzoylecgonine, ecgonine, nor-benzoylecgonine and methyl ecgonine--constituted approximately 88 and 97% of all metabolites in PM and LV specimens, respectively. The concentrations of nor-cocaine and nor-cocaethylene were consistently the lowest of all cocaine metabolites. At benzoylecgonine concentrations below 100 ng/mL, ecgonine was present at the highest concentrations. In 20 urine specimens, benzoylecgonine and ecgonine median concentrations (range) were 54 (0-47) and 418 ng/mL (95-684), respectively. Therefore, detection of ecgonine is advantageous when benzoylecgonine concentrations are below 100 ng/mL.     

葡萄糖对油制气废水生物降解影响的初步研究

采用3种驯化分离的菌种S-2、Y-3、XH-3及其混合菌M-3,以葡萄糖作为共代谢基质,研究了葡萄糖对各菌降解油制气废水的影响.结果表明:加入葡萄糖,可使COD、氨氮、可萃取有机物的去除率分别提高16.9%～26.5%、17.5%～31.2%、15.2%～23.3%;但在所采用的时间范围内,酚类化合物的去除率降低.加入葡萄糖,各菌对废水中芳烃类化合物的去除率提高17.7%～21.7%.除了维持无营养物条件下对芳环数≤3芳烃类化合物的良好降解能力外,对芳环数为4～6芳烃类化合物的降解能力也有所提高.     

醋酸纤维素扩散限制膜修饰葡萄糖生物传感器

为拓宽葡萄糖生物传感器检测的线性范围,分别利用质量浓度为0g/L、10g/L、15g/L、20g/L、25g/L和30g/L醋酸纤维素扩散限制膜,对以二茂铁为电子媒介体明胶戊二醛固定葡萄糖氧化酶制备的葡萄糖丝网印刷金电极进行修饰,研究了醋酸纤维素扩散限制膜对葡萄糖生物传感器性能的影响.结果表明,醋酸纤维素扩散限制膜有效地拓宽了葡萄糖生物传感器检测的线性范围,质量浓度为20g/L醋酸纤维素制备的扩散限制膜修饰的葡萄糖生物传感器性能最优,具有良好的产业化前景,其检测线性范围为0～30mmol/L,响应时间为10s,灵敏度为31.4μA/(mol·L-1),相关系数为0.99733.     

急性力竭游泳后小鼠血液成分变化的动态观察

为了观察急性力竭游泳对小鼠血液成分的影响,分别于小鼠力竭游泳停止后0(即刻)、1、4、8和24 h时进行尾静脉取血,测定了其白细胞、红细胞、血小板和血红蛋白等指标.结果表明:白细胞的数量在小鼠力竭游泳后0 h为(8.46±3.20)×109/L,与对照组的(10.65±2.29)×109/L比较明显减少(P＜0.05);在4 h时为(17.67±3.41)×109/L,与对照组比较显著增多(P＜0.01);在8 h以后恢复正常.红细胞的数量在小鼠力竭游泳后4 h时为(9.99±0.95)×1012/L,与对照组的(10.87±0.79)×1012/L比较明显减少(P＜0.05);在8h以后恢复正常.血小板的数量在小鼠力竭游泳后1、4、8和24 h时分别为(856.5±129.0)×109、(859.5±67.9)×109、(874.1±96.5)×109和(875.7±124.8)×109/L,与对照组的(721.5±115.7)×109/L比较均明显增多(P＜0.05).说明急性力竭游泳对小鼠血液中不同成分的作用存在差异,在一定时间内导致红细胞数减少、血小板增多和白细胞数先降后升的现象.     

鹰嘴豆对小鼠血糖及血脂的影响

本文以新疆地产的鹰嘴豆（Cicer arietinum）为受试样品，用高血糖模型小鼠研究鹰嘴豆调节血糖和血脂的作用．选取27只健康小鼠并随机分为三组；对照组，鹰嘴豆低剂量组（10g／kg／d），鹰嘴豆高剂量组（20g／kg／d），将鹰嘴豆粉与普通饲料混合，喂养12天后，测定其空腹血糖、血清胆固醇（TC）、甘油三酯（TG）含量，并对所得数据进行统计学处理，以此来作为对鹰嘴豆调节血糖血脂的功能评价。结果表明：鹰嘴豆对高血糖小鼠具有很好的降糖和降血脂作用，对预防糖尿病及其并发症具有积极意义。     

碳纤维电极的研制

本文详细叙述了碳纤维电极的研制工艺，并对其性能进行了测试，碳纤维电极的峰高均值为268．57μ A/V，变异系数为1．213％。GC电极的峰高均值为37.3μ A/V，变异系数为1．553％，碳纤维电极具有比GC电极更高的稳定性。在5．0mg/L Hg^2 -0.12mole/L盐酸溶液中测量铅，检测限达到0．020μ g/L(电富集600秒)，并且用于血液中痕量铅的测定，标准加入回收率为93．5％。RSD(n＝11)＜8．3％。     

高效液相色谱法测定菊粉酶解产物

采用高效液相色谱法以Shim-pack CLC-NH₂ 柱为分析柱，乙腈与水(体积比为7∶3)为流动相，以RID-6A示差折光仪为检测器，测定了菊粉酶解产物中的葡萄糖、果糖和蔗糖 ,为菊粉酶解产物的测定提供了科学依据。     

家蚕血液中微粒子Nosema bombycis种群增殖模型研究

为了进一步认识家蚕微粒子病在生产中的流行规律，提高防微工作的科学性，利用微生态学方法对家蚕微粒子进行了研究，通过对蚕体血液内子NosemaBombycis种群数量的动态分析，认识了NosemaBombycis孢子在蚕体血液内的增殖规律，为家蚕微粒子病的防治以及预测预报等工作提供科学的依据，从而指导生产实践，找出最优的防治方案及措施，力争把该病的危害控制在最低限度。