Determination of petroleum sulfonates in crude oil by column-switching anion-exchange chromatography

A column-switching anion-exchange chromatography method was described for the separation and determination of petroleum monosulfonates （PMS） and petroleum disulfonates （PDS） in crude oil that was simply diluted with the dichloromethane/methanol （60/40）. The high performance liquid chromatography （HPLC） system consisted of a clean-up column and an analytical column, which were connected with two six-port switching valves. Detection of petroleum sulfonates was available and repeatable. This method has been successfully applied to determine PMS and PDS in crude oil samples from Shengli oil field.

Development of simple HPLC/UV with a column-switching method for the determination of nicotine and cotinine in hair samples

Nicotine and cotinine in hair are good biomarkers for assessing long-term exposure to smoking. However, analytical devices such as GC/MS are associated with high cost and are not widely used. HPLC/UV is used widely in laboratories, but is unsuitable for measurement of minor constituents, except when using the column-switching method. Thus, we aimed to establish a simple, inexpensive and sensitive method based on HPLC/UV with column switching for measuring nicotine and cotinine in hair. First, we compared the presence and absence of a column selection unit. We then measured amounts of nicotine and cotinine in hair samples collected from the general population, and compared both the corresponding levels and the detection limits with those in previous studies. Finally, initial and running costs of HPLC/UV were compared with other analytical methods. As one of the results, the areas of nicotine and cotinine measured by HPLC/UV with column-switching method were 12.9 and 16.9 times greater, respectively, than those without the column-switching method. The amount of nicotine and cotinine in hair was significantly correlated to number of cigarettes smoked per day (r = 0.228, p = 0.040). In addition, the HPLC/UV method showed similar sensitivity and detection limit (nicotine, 0.10 ng/mg;cotinine, 0.08 ng/mg) as reported in previous studies. The cost of the HPLC/UV method is lower than that of other analytical methods. We were able to establish a low-cost method with good sensitivity for measuring nicotine and cotinine in hair. The HPLC/UV with a column-switching method will be useful as a first step in screening surveys in order to better understand the effects of smoking exposure.

Determination of Lansoprazole by Direct Injection of Plasma and High Performance Liquid Chromatography with Column Switching

High performance liquid chromatography with column switching has been developed for the determination of lansoprazole in plasma. The plasma samples were injected onto a pretreatment column packed with LiChromprep RP2 (25～40 mm) after simple dilution with distilled water. Distilled water was used to wash out protein and other polar components in plasma. After switching, the concentrated lansoprazole was eluted in the backflush mode onto a Shimpack CLC ODS column with methanol 0 2 mol·L 1 ammonium acetate (65:35) as mobile phase. Purge solutions were used for clean up and for regenerating the pretreatment column. The method showed good precision and recovery. The detection limit was 0 005 mg·L -1 plasma. The RSD’s (intra and interday) were less than 2 5% and 5 3% respectively. The method has been successfully used to determine pharmacokinetics of lansoprazole in Chinese volunteers.

All-optical switching and nonlinear optical properties of HBT in ethanol solution

This paper demonstrates an all-optical switching model system comprising a single pulsed pump beam at 355 nm and a CW He-Ne signal beam at 632.8 nm with 2-（2＇-hydroxyphenyl）benzothiazole （HBT） in ethanol solution. The origins of the optical switching effect were discussed. By the study of nonlinear optical properties for HBT in ethanol solvent, this paper verified that the excited-state intramolecular proton transfer （ESIPT） effect of HBT and the thermal effect of solvent worked on quite different time scales and together induced the change of the refractive index of HBT solution, leading to the signal beam deflection. The results indicated that the HBT molecule could be an excellent candidate for high-speed and high-sensitive optical switching devices.

Identification of Glyphosate Herbicide with Ion Chromatographic Column Switching Method

[Objective] The paper was to establish the method for quantitative analysis of glyphosate herbicide and identification of salt type. [Method] Using ion chromatographic column switching method,cations( sodion,ammonium ion,potassium ion,dimethonium ion and isopropylamine ion) and glyphosate anion in glyphosate salt were determined with Thermo IonP ac SCS1 cation exchange column and Thermo IonP ac AS14 anion exchange column,and external standard method was used for quantification. [Result] Various components showed good linear relationship within the linearity range,and the correlation coefficient r was greater than 0. 999; the relative standard deviation of retention time and peak area were less than 0. 13% and 1. 22%,respectively; the recovery was 98. 22%-99. 97%.[Conclusion] The method is precise,accurate and simple,and can be used to determine the active ingredients of glyphosate herbicide.

Highly reliable bipolar resistive switching in sol-gel derived lanthanum-doped PbTiO_3 thin film: Coupling with ferroelectricity?

Nanoscale PbxLa1-,Ti1-x/4O3 （PLT） thin film has been fabricated on Pt／Ti／SiO2／Si substrates by chemical solution deposition （CSD） method. Ferroelectricity of the fresh-made PLT thin film has been clearly detected through piezoelectric force microscopy （PFM） by writing reversible ferroelectric domains. However, PLT thin film also shows off-standard ferroelectric hysteresis loops highly dependent on frequency, indicating large amount of mobile space charges in the film. Subsequent current-voltage （C-V） studies show that sandwich-like Pt／PLT／Pt structure exhibits notable bipolar resistive switching （BRS） characteristics with high stability （〉 103 switching cycles）. It is found that the C-V curves of both high- and low-resistance states have the feature of space-charge-limited current （SCLC） conduction, indicating important roles of defects in the conduction. X-ray photoelectron spectroscopy measurement further verifies that oxygen vacancies based conductive filament mechanism is likely responsible for the observed RS effect. Our demonstration of stable RS effect in the PLT thin film and its possible coupling with ferroelectricity is promising in device development and applications, such as development of ferroelectric-tunable RS memories.

Improvement on Switching Characteristics and Switching Losses of IGBT by ZVS-PWM

Absrtact: The principle of ZVS - PWM inverting circuit is first described by means of inverting welder supply. The contrastive study is made on switching characte -ristics and switching losses of IGBT between ZVS - PWM and hard - switching.

Output Feedback Controller Design for Discrete-time Switched Singular Systems

This paper is concerned with the problems of robust admissibility and static output feedback( SOF)stabilization for a class of discrete-time switched singular systems with norm-bounded parametric uncertainties.The objective is to design a suitable robust SOF controller guaranteeing the regularity,causality and asymptotic stability of the resulting closed-loop system under arbitrary switching laws. Based on the basic matrix inequality sufficient condition for checking the admissibility of switched singular systems,together with some matrix inequality convexifying techniques,the SOF controller synthesis is developed for the underlying systems. It is shown that the controller gains can be obtained by solving a set of strict linear matrix inequalities( LMIs). A simulation example is given to show the effectiveness of the proposed method.

Egg White Protein-Bonded Columns and Their Applications

Egg white protein bonded columns were developed for HPLC. These columns can be used under aqueous mobile phase and separate various kinds of drug enantiomers. Hyphenated techniques using protein bonded columns with LC/MS and/or column switching have been recognized as integral methods in pharmaceutical research to analyze drug enantiomers. Therefore, these methods are very useful for research fields of pharmacokinetics and pharmacology.

Room Temperature Phosphorescence pH Switch Based on Photo-induced Electron Transfer

In this paper, photoinduced electron transfer(PET) phosphoroionophore, N-(1-bromo- 2-naphthylmethyl)-diethanolamine (BND) was synthesized and its phosphorescent characteristics were studied. The experimental results showed that strong phosphorescence could be observed in b-cyclodextrin aqueous solution only at low pH value. This system combined AND and NOT function to produce a three-input inhibit (INH) logic gate.

离子色谱-柱切换法测定土壤浸出液中的氟离子

建立了离子色谱-柱切换测定土壤浸出液中氟离子的方法。使用柱切换技术,将样品通过高聚物反相色谱柱进行在线预处理,分离氟离子和小分子有机酸,同时除去水溶性有机杂质,采用收集环收集氟离子并进入分析系统分析,消除了测定氟离子时普遍存在的干扰问题。分析系统的淋洗液为KOH溶液,流速为1.0 mL/min,采用抑制性电导检测,外标法定量。氟离子的线性范围为0.05~10.0 mg/L,相关系数为0.999 9,加标回收率为103.4%~105.3%,相对标准偏差为2.0%~2.1%,检出限（S/N=3）为5.50μg/L。该方法适用于测定复杂基体样品中的氟离子。

离子色谱-柱切换技术同步测定饮料中的三氯蔗糖、葡萄糖、果糖和蔗糖

建立了-种离子色谱-柱切换-安培检测技术同步测定饮料中三氯蔗糖、葡萄糖、果糖和蔗糖的方法.以 CarboPac PA10阴离子交换保护柱和分析柱进行分离,用水和250 mmol/L NaOH梯度淋洗,脉冲安培检测.弱保留 糖类在25 mmol/L NaOH流动相淋洗下分离检测,通过柱切换将保护柱切换至分析柱后,同时切换至250 mmol/L NaOH淋洗,三氯蔗糖仅通过较短的保护柱分离,4种糖类能够得到同步检测.4种糖类在0. 01 -20 mg/L 范围内 有良好的线性关系和较低的检出限,重复性好,样品测定的回收率分别为90. 38%- 102. 88% （三氯蔗糖）、95. 56%- 102. 75% （葡萄糖）、101. 66% - 114. 33% （果糖）和105. 03% - 106. 49% （蔗糖）.该方法可广泛应用于食品中强保留 物质的测定.

柱切换-反相高效液相色谱法测定血浆中沙丁胺醇浓度

目的 采用柱切换对反相高效液相色谱法测定血浆中沙丁胺醇浓度的方法进行改进。方法 采用Ultrasphere CN色谱柱 ( 2 5 0× 4.6m m,5μm )和 Krom asil C1 8( 2 0× 4m m,5μm )预处理柱 ,分析和预处理柱均以p H 2 .8、0 .0 2 5 mol/L磷酸盐缓冲液∶乙腈∶甲醇 ( 95∶ 4∶ 1)为流动相 ,吗啡作内标。血浆样品加入含二苯基硼酸 - 2 -氨基乙脂的缓冲液 ( p H 9.0 )后 ,用含四辛基溴化铵的氯仿萃取 ,再用 0 .0 8m ol/L醋酸 3 0 0μl反萃 ,取酸液10 0μl进样 ,预处理柱 0 .7～ 1.5 m in流出组份进入分析柱分析 ,2 2 4nm波长下检测 ,按内标法定量。结果 标准曲线线性范围为 0 .5～ 3 2μg/L ,最低定量限为 0 .5μg/L ,沙丁胺醇和内标的保留时间分别为 6.7min和 7.6m in,日内 RSD小于 5 % ,日间 RSD小于 8% ,萃取回收率大于 80 % ,方法回收率在 96%～ 10 7%。结论 本法具有快速简便 ,灵敏准确等特点 ,适用于沙丁胺醇血药浓度测定及药代动力学。

在线柱切换RP-HPLC测定人血清中卡马西平浓度

目的:通过在线样品预处理柱切换技术建立测定人体血清中卡马西平血药浓度的高效液相色谱法。方法:样品预处理采用 LiChroCART(25 mm×4 mm,25μm)预柱,分析柱为 Microsorb-MV C_(18) column(150 mm×4.6 mm,4μm);以水-乙醇(95:5,v/v)为血清蛋白冲洗流动相(流速2 mL·min^(-1)),水-乙醇(40:60,v/v)为分析流动相,流速0.8 mL·min^(-1);柱温:室温;检测波长285 nm。结果:本方法线性范围为2.0～40.0μg·mL^(-1),r=0.9997,定量下限为2μg·mL^(-1),日内、日间精密度 RSD 小于5%,方法回收率均大于95%。结论:该方法准确、稳定,灵敏度高,适用于卡马西平临床治疗药物监测的需要。

气相色谱毛细管柱切割-反吹技术及归一化法分析汽油中的芳烃(英文)

发展了一种采用毛细管气相色谱柱切割 反吹技术分析汽油中芳烃的方法。利用强极性毛细管预柱将芳烃保留至n C10 的脂肪族化合物之后 ,并将其反吹到非极性毛细管柱中按沸点详细分离分析。该方法使预柱先流出的组分和分析柱流出的组分通过一个微型三通进入同一检测器中 ,因此可用归一化方法定量分析汽油中的芳烃。该方法可在 15min内完成汽油中苯至C10 芳烃的分析 ,结果的相对标准偏差 (RSD)≤ 3% ,切割误差为± 5s时分析结果的RSD≤ 4 %。

柱切换LC-MSn法分析阿莫西林钠克拉维酸钾原料的杂质谱

目的对阿莫西林钠克拉维酸钾复方原料中的杂质结构进行分析。方法采用BDS Hypersil C18色谱柱,以0.01mol/L磷酸二氢钾溶液(pH6.0)-乙腈为流动相进行梯度洗脱分离杂质;对阿莫西林钠克拉维酸钾(5:1)原料进行强力实验,归属杂质来源;采用柱切换-LC/MSn技术采集杂质的质谱数据,根据青霉素类抗生素的质谱裂解规律和降解反应机理,推定相关杂质的化学结构。结果在原料中共检出并推断出11种杂质的化学结构,均为阿莫西林相关杂质,未检出与克拉维酸钾相关的杂质。结论采用柱切换-LC-MSn技术可快速推定阿莫西林钠克拉维酸钾复方原料中相关杂质的化学结构,为《中国药典》中该类药品标准的提高提供了基础数据。

柱切换技术-高效液相色谱法快速检测大鼠血浆中的普萘洛尔对映体

建立了快速检测大鼠血浆中普萘洛尔对映体浓度的柱切换-高效液相色谱法。将自制限进填料柱作为预处理柱,通过直接进样方式,使普萘洛尔对映体在预处理柱上保留,同时除去血浆中的蛋白质等大分子;再通过柱切换技术,使普萘洛尔对映体在键合型纤维素-三(3,5-二甲基苯基氨基甲酸酯)(Chiralcel OD-RH)分析柱上得到手性拆分。通过条件优化,确定切换前预处理流动相为硼酸盐缓冲液(pH 8.5)-甲醇(95∶5,v/v),流速为1.0mL/min;切换后分析流动相为异丙醇-乙醇-0.2 mmo l/L硼酸盐缓冲液(pH 8.5)(30∶30∶40,v/v/v),流速为0.8mL/min;切换时间为3 min;柱温为25℃;检测波长为293 nm。普萘洛尔两对映体在25～500 mg/L的质量浓度范围内具有良好的线性关系(r=0.999 5),3个加标水平(50、100、250 mg/L)的平均回收率为97.89%～101.56%,日内和日间精密度均小于5%。该方法简便、快速、灵敏、准确,适于血浆样本中手性药物的药代动力学研究。

电子制冷预浓缩-双柱气相色谱-质谱/氢火焰检测器法测定空气中104种挥发性有机物

基于吸附剂辅助电子制冷预浓缩技术,建立了多维切割双柱气相色谱-质谱/氢火焰离子化检测器(GC-MS/FID)同时测定环境空气中104种挥发性有机物(VOCs)的方法。将采集于苏玛罐中的环境空气样品在配有吸附剂的电子制冷预浓缩系统中富集、脱附、除水、除CO_2和浓缩,然后通过GC-MS/FID的多维切割单元将C_2～C_3组分和C_4～C_(12)组分分别引入PLOT柱和InterCap-624柱进行分离。C_2～C_3组分用FID检测,以保留时间定性、外标法定量;C_4～C_(12)组分采用电子轰击离子源质谱检测,以保留时间和特征离子定性、内标法定量。考察了冷阱吸附剂种类、辅助压力控制单元压力设置、双柱切换时间切割点等参数对分析结果的影响,优化了GC-MS/FID条件,并评估了在此优化条件下的方法性能。104种VOCs在0.044 6～0.892μmol/m^3范围内线性关系良好,相关系数(r)为0.998 4～0.999 9,对0.044 6μmol/m^3和0.223μmol/m^3水平的混合标准气体重复6次进样,平均回收率为86.4%～116.1%,相对标准偏差为0.9%～11.3%;方法的检出限为0.145～1.90μg/m^3,定量限为0.435～5.70μg/m^3。该法稳定性好,灵敏度高,操作简便,可用于环境空气中104种VOCs的测定。

毛细管色谱切割-反吹法归一化分析汽油中芳烃

发展了一种毛细管色谱切割 反吹方法分析汽油中的芳烃。利用OV 2 3 3 0强极性毛细管预柱将芳烃保留至n C1 0 之后 ,并反吹到非极性毛细管柱中按沸点详细分离分析。从预柱先流出的组分和从分析柱流出的组分都先后进入同一检测器中 ,因此可用响应因子校正的归一化方法定量分析汽油中的芳烃。该方法在15min内完成汽油中苯至C1 0 芳烃的分析 ,结果的重复精度误差≤ 3 % (RSD) ,切割误差± 5s时对分析结果的影响≤ 4% (RSD)。