Determination of L‐ and D‐Enantiomers of Leucine Using Amperometric Biosensors Based on Diamond Paste

Abstract

Four amperometric biosensors, based on diamond paste, are proposed for the determination of the enantiopurity of leucine. The design of the biosensors used physical immobilization in diamond paste of L‐amino acid oxidase for the assay of L‐leucine and D‐amino acid oxidase for the assay of D‐leucine. The response characteristics of the different diamond paste based biosensors were obtained and compared. The linear concentration ranges for the biosensors were in pmol/L to nmol/L magnitude order. The biosensors showed high reliability for the determination of enantiopurity of leucine as a raw material.     

ON-LINE MONITORING OF R-CAPTOPRIL USING AN AMPEROMETRIC BIOSENSOR/SEQUENTIAL INJECTION ANALYSIS SYSTEM

ABSTRACT

An automated system for the on-line monitoring of R-captopril, based on the concept of sequential injection analysis with an amperometric biosensor (based on D-amino acid oxidase) as detector, is described. The sampling rate is 80 samples per hour with an RSD <0.22% in the linear range between 0.2 and 1.0?μmol/L. The detection limit is 160?nmol/L.     

An Inexpensive Sequential Injection Analyzer for the Analytical Laboratory

Abstract

A home‐made multiposition valve and a syringe pump were specially designed and fabricated using inexpensive and easily available materials and equipment in the laboratory. The hardware and software for controlling the devices and displaying the signal were developed. Both devices were combined to obtain a sequential injection analysis (SIA) system and used by incorporating with a spectrophotometric detector. The developed SIA analyzer is computerized. The SIA system can select the samples and reagent, which is then sequentially injected into the holding coil where the sample and the reagent zones are taking place. Both sample and reagent zones are delivered into a flow‐through detector where the reaction product is measured spectrophotometrically. The program for interfacing the SIA instrumentation with a personal computer was also developed using Microsoft Visual Basic?. This can enable a wide range of chromophores to be automatically detected. The fabricated SIA analyzer was tested for determining Fe(III) in standard solution based on Fe(III)‐thiocyanate complex. The RSD for 11 replicates determination of 4.0 mg/L iron was 1.08%. The detection limit (3σ) and the determination limit (10σ) were 0.34 and 1.13 mg/L, respectively. A linear calibration curve over the range of 1.0–7.0 mg/L iron and correlation coefficient of 0.9977 were established. The analyzer has been successfully applied to the determination of total iron in waters. Results obtained by both the proposed SIA and AAS methods were in excellent agreement.     

Development of an Amperometric Biosensor and Performance Studies with a Minimum Background Current

Abstract

An amperometric glucose biosensor with immobilized glucose oxidase enzyme is developed and its performance is investigated for the analysis of glucose concentration. A systematic method to find the background current in an amperometric biosensor is proposed, and the procedure for the minimization of the current has been reported. Tests were conducted for the analysis of glucose in different fruit juices. The current generated in an enzyme based amperometric biosensor depends on both the sensing current and the background current. The performance of amperometric biosensor is better when it is operated at optimized operating conditions and with minimum background current. The effect of current caused by the interference contained in the physiological fluids (uric acid and ascorbic acid) is found negligible. It has been found that the thickness of the membrane will affect the response time and the increase in background current will affect the sensitivity.     

非抑制离子色谱测定工作场所空气中的一乙醇胺、二乙醇胺和三乙醇胺

建立了以甲基磺酸(MSA)和乙腈混合淋洗,离子交换色谱分离,非抑制电导检测,分析工作场所空气中的一乙醇胺、二乙醇胺和三乙醇胺的方法。用5mmol/L甲基磺酸水溶液做为吸收液来采集空气样品,吸收效率满足采样要求;采集后的吸收液直接注入离子色谱系统进行测定。优化了离子色谱同时测定三种化合物的色谱条件;在最佳条件下,方法的检出限在24μg/L-50μg/L之间,将该方法用于实际空气样品的检测,回收率为93.2%~107.6%。该方法可适用于不同场所中空气中一乙醇胺、二乙醇胺和三乙醇胺的测定。     

SIMPLE LABORATORY-MADE AUTOMATED SEQUENTIAL INJECTION ANALYSIS (SIA) DEVICE. II. SIA OPERATIONAL SOFTWARE BASED ON LABVIEW® PROGRAMMING LANGUAGE

ABSTRACT

The paper presented deals with the development of an automated computer-aided sequential injection analysis (SIA) system and its application to laboratory automation. In Part I, hardware and technical parameters of the SIA system were described. Part II introduces original lab-developed operational software (FaFSIA), enabling one to control the cited SIA system and to process experimental data, including their presentation. The software, based on graphic programming language LabVIEW, is described in detail.     

Fluorimetric Determination of Aluminium using Sequential Injection Analysis (SIA): State of Our Art and Future Developments

Abstract

This paper describes some of our recent advances and proposed future work in the area of fluorimetric determination of Al using sequential injection analysis (SIA). A rapid, automated system was developed with turnover times for sample analysis of <2 min, and attainable limits of detection of <1 ng/mL. The method is cost‐effective and highly competitive. It utilizes three different approaches: (i) molecular imprinted polymers (MIPs); (ii) micellar enhanced treatment; and (iii) renewable surface application. The merits and limitations of each approach are discussed, and the optimum conditions of analysis are presented. The overall sensitivity achieved was more than adequate for general analysis. Proposed new developments involve greater signal enhancement, and improved analytical strategy. The facility is capable of routine application, and is highly beneficial to developing countries in need of cost‐effective techniques for analysis of environmental samples, body fluids, and foodstuffs.     

高效液相色谱法同时测定猪肉中克伦特罗、沙丁胺醇、土霉素、四环素残留量的研究

建立高效液相色谱法(HPLC)同时测定猪肉样品中克伦特罗、沙丁胺醇、土霉素、四环素残留量的检测方法。样品用0.01 mol/LEDTA-2Na、0.3%磷酸溶液、高氯酸(1∶1)混合溶液提取,上清液过C18固相萃取柱净化,采用高效液相色谱分离,二极管阵列检测器(DAD)检测,外标法定量。本法简便、快速、定量准确、精密度高,适用于猪肉样品中克伦特罗、沙丁胺醇、土霉素、四环素残留量的检测。     

自动富集-单光子电离质谱在线测量氯酚的研究

氯酚类化合物是垃圾焚烧所产生的二噁英前生体之一,对二噁英的浓度有很好的指示作用。针对气相中氯酚类二噁英前生体的在线连续监测,自行研制了全自动富集进样-单光子电离-反射式飞行时间质谱仪。为实现低浓度氯酚的检测,设计了全自动的富集进样系统,利用3根阵列式Tenax TA吸附管,结合全自动控制的高温电磁阀,实现了气体样品连续自动的“富集 热解析-质谱进样”。研制的反射式单光子电离-飞行时间质谱仪采用10.6 eV真空紫外灯作为光电离源,对气体样品分子进行软电离,避免了碎片离子的产生,所获得的样品分子离子经反射式飞行时间质量分析器完成检测,仪器分辨率达到3 000（m/z 78）。以3种典型的二噁英前生体氯酚类化合物（邻氯苯酚、2,4-二氯苯酚、2,4,6-三氯苯酚）为检测对象,对该仪器性能进行考察。富集进样系统对3种氯酚类化合物的富集倍数分别达到60、249、503,检测限分别达到66、120、125 pg/L,动态线性范围分别为166 pg/L~16.6 ng/L、210 pg/L~21 ng/L、255 pg/L~25.5 ng/L。这些研究结果为今后开展垃圾焚烧烟气中二噁英的现场连续监测工作奠定了基础。     

Flash HT和GasBench II-IRMS分析水中氢氧同位素的方法比较

为了建立一种更准确、更快速的水中氢氧同位素比值检测分析方法,采用在线的连续流元素分析仪 稳定同位素质谱仪联用（Flash HT-IRMS）,碳还原高温热转化法和多用途气体制备仪-稳定同位素质谱仪联用（GasBench II-IRMS）水平衡法分析了不同来源水样中的氢氧同位素组成。结果显示,Flash HT和GasBench II-IRMS两种分析系统均能获得较好的氢氧同位素分析测试精密度,分别小于0.5‰（δD）和0.1‰（δ¹⁸O)。对比两种分析系统,Flash HT-IRMS分析系统的重现性和精度均优于GasBench II-IRMS。另外,Flash HT-IRMS分析系统可以实现在线单次分析过程中同时测定水中氢氧同位素组成,而且分析时间短、样品消耗量少,仅需0.1 μL。因此,对于微量水样中氢氧同位素组成的分析,Flash HT-IRMS测定系统更具优势。     

脉冲安培检测-离子色谱法测定牛奶中的微量碘离子

以硝酸作淋洗液,选用亲水性较强的ASI 1分离柱,脉冲安培检测的方式测定了日常食用的鲜牛奶中的微量腆离子.在0.005～1.0 mg/L范围内,碘离子的浓度X与对应的色谱峰面积Y呈良好的线性关系,碘离子的线性方程为:Y=0.1112X-0.2490;r=0.9993;峰面积和保留时间的RSD值分别为0.971%和0.1...     

液相色谱-串联质谱法快速检测干血点样品中尿酸

建立了一种高通量液相色谱-串联质谱（LC-MS/MS）检测干血点(DBS)样品中尿酸(UA)的方法。采用自动液体操作平台对样品进行高通量自动化前处理,首先用含有UA-1,3-¹⁵N₂稳定同位素内标的Tris水溶液进行萃取,然后用含有0.1%甲酸、0.05%三氟乙酸的乙腈溶液沉淀蛋白质。处理后的样品经CN色谱柱分离,多反应监测(MRM)模式进行LC-MS/MS分析。结果表明,在DBS样品中,UA在7.8~1 000 μmol/L浓度范围内的线性关系良好(R²＝0.999);检出限为3.1 μmol/L (S/N=3);定量限为12.5 μmol/L(S/N=10);平均回收率为95%~101%;日内相对标准偏差(RSD)为4.2%~12%;日间RSD为5.3%~14%。以样品中UA检测结果的总体RSD不超过15%来考察样品稳定性,分别将样品在-20 ℃保持30天、在37 ℃保持7天、反复冻融5次,样品中UA检测结果总体RSD小于10%,表明样品稳定性良好。将该方法与传统生化分析方法相比较,并分析了204份血样,相关性较好(R²＝0.946)。此方法可为有限采血条件下UA的检测及UA相关疾病的大规模筛查提供新途径。     

化妆品中砷、锑无机形态的HPLC-HGAFS同测

本文通过优化样品提取条件、色谱分离条件、柱后处理条件和仪器检测条件,采用高效液相色谱-氢化物发生原子荧光光谱联用(HPLC-HGAFS)技术建立了化妆品中Sb(III)和Sb(V)以及As(III)和As(V)形态的同时测定的方法。重点研究了提取液组成对Sb形态转化的影响和Sb(V)柠檬酸络合物的柱后转化条件,结果表明在1:1的柠檬酸-柠檬酸钠的缓冲溶液中Sb的各个形态相互转化率最低;提取得到的Sb(V)的柠檬酸络合物可以在HCl+KI溶液中在线还原为Sb(III)的柠檬酸络合物而得以检测。该方法对As(III)、As(V)、Sb(III)和Sb(V)的检出限分别为2.4、3.1、0.5和5.0μg/L,线性范围分别是2.4～1000、3.1～1000、0.5～1000和5～1000μg/L,该区间内的线性相关系数均大于0.9990,标准偏差均小于3.0%。采用本方法对粉剂、液态、固态等化妆品进行了测定,其加标回收率都在77～110%之间,证明该方法适用于同时测定化妆品中锑和砷的无机形态。     

Construction and Applications of a Microcomputer Controlled Pulsed Amperometric Detector System

ABSTRACT

The construction of a microcomputer controlled pulsed amperometric detector system is described. It includes a potentiostat, a flow-through cell and a sample injection unit. The microcomputer generates the appropriate waveform of the applied potential and controls the overall sequence of the measurement. The system is suitable for general studies on the detection of various classes of organic compounds with the pulsed amperometric technique. The detectability of various hydroxycompounds has been studied.     

超高效液相色谱-串联质谱法测定保健食品中10种磷酸二酯酶-5抑制剂

建立了超高效液相色谱-串联质谱法（UPLC-MS/MS）同时测定保健食品中10种磷酸二酯酶-5（PDE-5）抑制剂。样品采用 Waters Acquity UPLC BEH C18（100 mm×2.1 mm×1.7 μm）色谱柱分离,以甲醇0.1%甲酸水溶液为流动相进行梯度洗脱,甲醇为提取溶剂超声萃取,经HLB固相萃取柱净化浓缩;在电喷雾正离子模式下,以多反应监测（MRM）模式进行检测。结果表明,10种磷酸二酯酶-5抑制剂在1.0～100.0 μg/L范围内线性关系良好,线性相关系数（R²）均大于0.993,方法定量限为1.0 μg/kg;空白样品在100.0、200.0和1 000.0 μg/kg添加水平下的回收率为85.6%～94.3%。该方法简便、快速、检出限低,适用于保健食品中10种磷酸二酯酶-5抑制剂的同时检测。     

FEMTOLITER MICROARRAY WELLS FOR ULTRASENSITIVE DNA/mRNA DETECTION

ABSTRACT

DNA/mRNA analysis and genetic mutation detection are important in biomedical sciences, clinical diagnosis, and environmental monitoring. In this study, a femtoliter microwell array system has been developed for ultrasensitive DNA/mRNA detection using molecular beacon (MB) DNA probes. The microwell array system, with laser-induced fluorescence imaging, can be used to achieve a detection limit of 9 Rhodamin 6G molecules in 28?fL (28?×?10^?15?L) wells in this array. Hybridization kinetics of the MBs and their complementary DNA targets has been monitored with a concentration detection limit of 3.0?nM. As few as 50 target DNA copies can be monitored in each well. The specificity of MB and the effect of DNA target concentration on the MB hybridization kinetics have been investigated in femtoliter wells. Analysis of specific rat γ-actin mRNA sequence amplified by polymerase chain reaction (PCR) and simultaneous measurement of multiple analytes have also been studied with this microwell array system. As the volume in each well is extremely small, this array system will be highly useful for single cell gene profiling and for multiple gene determination in disease diagnosis.     

毛细管电泳-质谱联用法测定葡萄酒中8种有机酸含量

应用毛细管电泳-电喷雾电离质谱(CE-ESI-MS)联用法同时测定葡萄酒中草酸,富马酸,琥珀酸,柠檬酸,苹果酸,抗坏血酸,酒石酸和乳酸8种主要有效成分的含量。在未涂层石英毛细管（50 μm×80 cm）中,以40.0 mmol/L醋酸铵（用1.0 mol/L醋酸调至pH 4.5）为缓冲溶液,30%异丙醇（含3.0 mmol/L氨水）为鞘液,分离电压25.0 kV,各组分在15 min内得到完全分离。草酸,富马酸,琥珀酸,柠檬酸,苹果酸,抗坏血酸,酒石酸和乳酸的线性范围分别为1.0~300.0、1.0~300.0、5.0~1 500.0、2.0~600.0、5.0~1 500.0、1.0~300.0、5.0~1 500.0和5.0~1 500.0 mg/L;检出限分别为0.2、0.05、1.0、0.5、1.0、0.3、1.0、1.0 mg/L;8种组分的加标回收率为87.6%~98.2%;相对标准偏差(RSD)在2.7%~5.6%之间。     

反向离子对色谱法同时测定多维矿物质软胶囊中维生素B_1、B_6、烟酸、烟酰胺和咖啡因

优化了保健食品中维生素B1、B6、烟酸、烟酰胺和咖啡因同时测定的反向离子对色谱法。样品经简单提取后,以乙腈-1-辛烷磺酸钠-磷酸水溶液作流动相,进行梯度洗脱,二极管阵列检测器（DAD）双波长（260nm、290nm）检测。5种物质在较宽浓度范围内线性关系良好,检出限（S/N=3）分别在0.01～0.08mg.L-1之间,平均加标回收率为90.8%～99.0%,相对标准偏差（RSD）为1.06%～4.98%。该方法适用于保健食品中维生素B1、B6、烟酸、烟酰胺和咖啡因的同时测定。     

顺序注射分析及其在环境监测中的应用进展

基于流动注射分析（FIA）发展起来的顺序注射分析（SIA）是一种流路简单、易于自动控制的溶液处理和分析方法，目前已成为流动分析研究最活跃的领域之一，但目前在国内开展工作不多。本文对此技术的概念、原理、实验装置、在环境监测中的应用及最新进展进行了综述，引用文献74篇。     

高效阴离子交换色谱—脉冲安培检测模拟海水中痕量溴和碘离子

本文建立了脉冲安培检测器同时测定模拟海水中溴和碘离子的离子色谱方法,选用IonPac AS 20型分析柱,通过对淋洗液种类和浓度进行详细的试验,最终确定采用60 mmol/L的NaOH溶液作淋洗液,流速为1.0mL/min的条件下进行测定,使Cl-、Br-和I-基线分离。高含量的氯对测定溴和碘不存在干扰,方法的线性相关性好（r2〉0.999）,检出限为0.2μg/L。样品测试的相对标准偏差RSD小于4%,加标回收率95.0%～100.0%。