液液萃取-气相色谱法测定尿液中的可卡因

目的:建立人体尿液中可卡因的快速提取及气相色谱-氢火焰离子化(GC-FID)检测方法。方法:用0.05 mol/L碳酸钠-碳酸氢钠缓冲溶液调节尿液pH9.5,提取溶剂:氯仿∶异丙醇=9∶1(体积比),液-液萃取10 min,气相色谱分析。结果:方法的平均回收率为84%,检出限50ng/mL,线性范围0.1～15μg/mL,精密度小于5.47%。结论:该方法可快速、准确进行可卡因滥用者的尿液分析。     

顶空气相色谱法测定盐酸氮卓斯汀中残留溶剂

建立毛细管气相色谱法测定盐酸氮卓斯汀中残留溶剂。采用DB-624毛细管色谱柱,FID检测器,二甲基甲酰胺为溶剂,程序升温,外标法同时检测盐酸氮卓斯汀中乙醇、丙酮、二氯甲烷、正己烷4种有机溶剂残留量。各待测组分完全分离,线性关系良好,检测限分别为3.51μg/mL、 0.35μg/mL、 2.12μg/mL、 0.11μg/mL,精密度RSD<5%,平均回收率99.1%-102.4%。本法操作简单,结果准确可靠,可用于盐酸氮卓斯汀中残留溶剂的检测。     

An improved single crystal adsorption calorimeter for determining gas adsorption and reaction energies on complex model catalysts

A new ultrahigh vacuum microcalorimeter for measuring heats of adsorption and adsorption-induced surface reactions on complex single crystal-based model surfaces is described. It has been specifically designed to study the interaction of gaseous molecules with well-defined model catalysts consisting of metal nanoparticles supported on single crystal surfaces or epitaxial thin oxide films grown on single crystals. The detection principle is based on the previously described measurement of the temperature rise upon adsorption of gaseous molecules by use of a pyroelectric polymer ribbon, which is brought into mechanical∕thermal contact with the back side of the thin single crystal. The instrument includes (i) a preparation chamber providing the required equipment to prepare supported model catalysts involving well-defined nanoparticles on clean single crystal surfaces and to characterize them using surface analysis techniques and in situ reflectivity measurements and (ii) the adsorption∕reaction chamber containing a molecular beam, a pyroelectric heat detector, and calibration tools for determining the absolute reactant fluxes and adsorption heats. The molecular beam is produced by a differentially pumped source based on a multichannel array capable of providing variable fluxes of both high and low vapor pressure gaseous molecules in the range of 0.005-1.5 × 10(15) molecules?cm(-2)?s(-1) and is modulated by means of the computer-controlled chopper with the shortest pulse length of 150 ms. The calorimetric measurements of adsorption and reaction heats can be performed in a broad temperature range from 100 to 300 K. A novel vibrational isolation method for the pyroelectric detector is introduced for the reduction of acoustic noise. The detector shows a pulse-to-pulse standard deviation ≤15 nJ when heat pulses in the range of 190-3600 nJ are applied to the sample surface with a chopped laser. Particularly for CO adsorption on Pt(111), the energy input of 15 nJ (or 120 nJ?cm(-2)) corresponds to the detection limit for adsorption of less than 1.5 × 10(12) CO molecules?cm(-2) or less than 0.1% of the monolayer coverage (with respect to the 1.5 × 10(15) surface Pt atoms?cm(-2)). The absolute accuracy in energy is within ～7%-9%. As a test of the new calorimeter, the adsorption heats of CO on Pt(111) at different temperatures were measured and compared to previously obtained calorimetric data at 300 K.     

Calibration method to characterize the accuracy of phase-shifting point diffraction interferometer

Characterization of measurement accuracy of the phase-shifting point diffraction interferometer (PS∕PDI) is usually performed by two-pinhole null test. In this procedure, the geometrical coma and detector tilt astigmatism systematic errors are almost one or two magnitude higher than the desired accuracy of PS∕PDI. These errors must be accurately removed from the null test result to achieve high accuracy. Published calibration methods, which can remove the geometrical coma error successfully, have some limitations in calibrating the astigmatism error. In this paper, we propose a method to simultaneously calibrate the geometrical coma and detector tilt astigmatism errors in PS∕PDI null test. Based on the measurement results obtained from two pinhole pairs in orthogonal directions, the method utilizes the orthogonal and rotational symmetry properties of Zernike polynomials over unit circle to calculate the systematic errors introduced in null test of PS∕PDI. The experiment using PS∕PDI operated at visible light is performed to verify the method. The results show that the method is effective in isolating the systematic errors of PS∕PDI and the measurement accuracy of the calibrated PS∕PDI is 0.0088λ rms (λ = 632.8 nm).     

气相色谱法-氮磷检测器检测污水处理厂进出水中有机磷农药残留

采用固相萃取全自动工作仪和Triazine前处理柱对污水处理厂的进、出水样进行前处理,用气相色谱法一氮磷检测器检测污水中测乐果、甲基对硫磷、马拉硫磷和对硫磷4种有机磷农药残留。研究了在不同铷珠电流值条件下氮磷检测器对4种有机磷农药的响应值。本法对乐果、甲基对硫磷和马拉硫磷的检出限为0．03ng／μL,对硫磷为0．005ng／μL,线性范围均为3-500ng／mL,加标回收率为79％～115％。试验结果证明,可以采用较大直径的毛细管柱进行污水中有机磷农药的测定。     

顶空气相色谱法测定双羟氟轻松中残留溶剂的含量

建立毛细管气相色谱法测定双羟氟轻松中残留溶剂。采用DB-624毛细管色谱柱,FID检测器,二甲基亚砜为溶剂,程序升温,外标法同时测定双羟氟轻松中甲醇、丙酮、二甲基甲酰胺和三氯甲烷等有机溶剂残留量。各待测组分完全分离,线性关系良好,检测限分别为1.20μg/mL、0.17μg/mL、11_32μg/mL和0.15μg/mL,精密度RSD<4%,平均回收率95.66%～106.31%。本法操作简单,结果准确可靠,可用于双羟氟轻松中残留溶剂的检测。     

气相色谱法测定雄烯二醇中的残留溶剂

用毛细管气相色谱法建立雄烯二醇7种残留溶剂的测定方法。采用DB-Wax（30m×0．45mrn,0．85μm）毛细管柱,载气为氮气,FID检测器。采用程序升温,柱温：起始温度为45℃,保持1Omin,然后以20℃／rain的速率升至140℃,保持10分钟。进样口温度：250℃,检测器温度：250℃。分流直接进样,N,N～二甲基甲酰胺为溶剂,丙酮为内标物,内标法测定残留溶剂的含量。在考察的范围内呈良好的线性关系（乙醇r=0．9997、吡啶r=O．9999、乙酸乙酯r=O．9995、甲苯r=O．99957、甲醇r=O．99997、二氟乙烷r=O．99995、乙酸r=O．9995）,样品加标回收率为100．1％～102．8％,理论塔板数大于10000,相邻峰的分离度均大于1．5,精密度、重复性的R,SD均小于5％。本法简单,结果准确,重复性好,适用于雄烯二醇中乙醇、吡啶、甲苯、乙酸、二氮乙烷、甲醇、乙酸乙酯7种残留溶剂的同时检测。     

Evaluation of Halogen‐Specific Detector (XSDTM) for Trace Analysis of Chlorinated Fatty Acids in Fish

Abstract

The applicability of a halogen‐specific detector (XSD?, manufactured by OI Analytical) was evaluated for GC analysis of chlorinated fatty acid methyl esters (FAMEs) that are present at trace levels in transesterified fish extract, a complex matrix consisting of similar but nonchlorinated compounds. A characteristic of the XSD working principle is that thermal electron emission, negative surface ionization and positive surface ionization are all operative in a concerted manner. While the XSD is not superior to other GC detectors in terms of signal‐to‐noise, its merit is in its high selectivity (10⁶) and low detection limit (2 pg Cl) for chlorinated fatty acids, and ease of operation and maintenance. Its reasonably wide linear range (up to 10 ng Cl) is desirable for trace analysis of chlorinated FAMEs. A major drawback of this detector is a certain degree of peak broadening and peak tailing of eluted compounds with concentrations larger than ～1 ng Cl/µL in the injected solution even though this value does not exceed the upper limit of the XSD linear range. Nevertheless, in trace analysis of chlorinated compounds, the concentrations of analytes are usually well below 1 ng Cl/µL. Parallel use of the XSD and a universal detector such as FID in gas chromatography is useful for optimizing operation conditions for trace analysis and simultaneously analyzing nonchlorinated major components.     

气相色谱法测定雌激素化合物S21中的残留溶剂

用毛细管气相色谱法建立S21中4种残留溶剂的测定方法。采用DB-Wax(30m×0.45mm,0.85μm)毛细管柱,载气为氮气,FID检测器。采用程序升温,柱温:起始温度为50℃,保持5min,然后以30℃/min的速率升至200℃,保持7min。进样口温度:250℃,检测器温度:250℃。分流直接进样,N,N-二甲基甲酰胺为溶剂,乙腈为内标物,内标法测定残留溶剂的含量。在考察范围内呈良好的线性关系(乙醇r=0.9997,丙酮r=0.9997,乙酸乙酯r=0.9998,甲苯r=0.9999),平均回收率为97%～100%,理论塔板数大于10000,相邻峰分离度均大于2,精密度、重复性的RSD均小于3%。本法简单、结果准确、重复性好,适用于S21中乙醇、丙酮、乙酸乙酯、甲苯4种残留溶剂的同时检测。     

毛细管气相色谱法测定塑料包装及其内食品中酞酸酯

建立了用毛细管气相色谱-氢火焰离子化检测器测定塑料食品袋及袋内包装食品中5种酞酸酯（邻苯二甲酸二甲酯（DMP）、邻苯二甲酸二乙酯（DEP）、邻苯二甲酸二丁酯（DBP）、邻苯二甲酸二正辛酯（DOP）和邻苯二甲酸二（2-乙基己基）酯（DEHP））的方法。样品用无水乙醇超声提取，经干燥脱水过0．45μm滤膜过滤，直接注入气相色谱仪进行分析。用保留时间定性，外标法定量。5种酞酸酯的回收率为71．5％～125．5％；精密度（RSD）为1．6％～3．2％；DMP、DEP、DBP、DOP和DEHP的检测限分别为0．18ng、0．13ng，0．13 ng、0．15ng和0．14 ng。该方法准确度和灵敏度高，样品用量少，前处理简单，可同时测定塑料食品袋及包装内食品中5种酞酸酯。     

高效液相色谱法-电雾式检测器测定酿酒酵母发酵液中甘油的含量

建立了高效液相色谱法-电雾式检测器检测酿酒酵母发酵液中甘油含量的方法。色谱柱采用Shodex Asahipak NH2P-504E（4．6mm×250mm）,柱温25℃。流动相采用乙腈-水（体积比为75：25）,流速1．0mL／min。最低检出限10ng,回收率95．06％～99．10％,相对标准偏差1．38％～4．87％。该方法简便、快速、准确,可用于酿酒酵母发酵液中甘油的测定。     

蒸馏法前处理联用离子色谱测定水体基质中氨氮

建立了一种用蒸馏法富集水体样品中氨氮并联用离子色谱技术检测的方法。该方法可以有效富集水体中的氨氮（以NH4＋形式）,并去除水体样品中的Na＋、K＋及其他基质离子的影响。以IonPac CS16色谱柱为分离柱,用甲磺酸等度洗脱方式使待测组分分离,流速为1mL/min,电导检测,外标法定量。在优化后的实验条件下,NH4＋的线性范围为0.01-50μg/mL,相关系数大于0.9991;将该方法应用于海水、湖水、苦咸水等水样的检测,实际样品加标回收率为86.8-106.8%,检测限为1.28ng/mL（信噪比S/N=3）。实验结果表明,该方法可以用于水体中氨氮的检测。     

Accurate measurements of water vapor transmission through high-performance barrier layers

We report a new approach to measuring very low rates of water vapor transmission through high-performance barrier layers, based on detection of the water vapor by cavity ring-down infrared spectroscopy. It provides accurate and traceable measurements with a detection limit for water vapor transmission significantly below 1 × 10(-4) g∕m(2)∕day. The system is underpinned by dynamic reference standards of water vapor generated between 5 and 2000 nmol∕mol with an estimated relative expanded uncertainty of ±2%. It has been compared with other methods and demonstrates good comparability.     

Li+ ion emission from a hot-plate alumina-silicate source stimulated by flash heating with an infrared laser

The Neutralized Drift Compression Experiment-II accelerator under construction at Lawrence Berkeley National Laboratory has been designed to employ a lithium-doped alumino-silicate (Al-Si) hot-plate surface-ionization ion source. In order to achieve the design 1 mA∕cm(2) current density, the emitter must be constantly kept at a high temperature, leading to the accelerated loss of Li material as ions or neutrals. As a result, the estimated lifetime of the source is 50 h. This lifetime can be extended if the source is kept at low temperature during standby, and pulse heated to the high temperature during the ion extraction phase only. A pulsed heating technique based on an infrared laser (CO(2) gas discharge, λ = 10.6 μm) is described in this paper. The feasibility of ion current emission stimulated by flash heating with an infrared (IR) laser was demonstrated. High repeatability of the laser-stimulated ion current was observed, creating an opportunity for modulation and gating of the ion current with a laser pulse. It was found that with the available low power (≈115 W∕cm(2)) IR laser, current densities as high as 0.8 mA∕cm(2) could be achieved with a 2.8 mm diameter source. Various approaches for scaling to a larger (10 cm diameter) source and the application of short pulse, high power lasers are discussed. The results and conclusions of this paper may apply to various species of hot-plate ion sources.     

Induction charge detector with multiple sensing stages

An induction charge detector yields the net charge and the time of flight of a particle. The unique ability to independently measure these two parameters sets apart this rather simple detection technique. The main shortcoming of this instrument is its high charge detection limit, resulting from the intrinsic noise of the detector electronics and the low signal associated with the charge to measure. The goal of the present work is to lower the detection limit of this detector. This article describes an induction charge detector whose main novelty is a sequence of aligned cylindrical electrodes for measuring the charge of a particle n times. In a time domain analysis, this feature reduces both the detection limit and the standard error of the charge measurement by factors of square root of 2 and square root of n. More importantly, sensing stages could be added to arbitrarily lower the detection limit in a frequency domain analysis.     

Preliminary characterization of a low-powered microwave induced flame plasma for direct organic solvent nebulization

A low powered (<90 W) microwave-induced plasma has been generated at atmospheric pressure by using a Beenakker cavity, a laboratory constructed torch, and a gas mixture of argon (400 ml/min), hydrogen (100 ml/min), and air (130 ml/min). This plasma has an excitation temperature of 3300-3500 K, electron number density of 7 × 10(14) cm(-3), and easily accepts direct methanol and ethanol introduction with a 1 ml/min solution nebulization rate. Detection limits (3σ) obtained from the atomic emission signals of Li, Sr, and Cr in water are 15, 120, and 290 ng/ml, respectively. Similarly, detection limits for the metals in methanol are 15, 120, and 260 ng/ml, respectively, and in ethanol they are 25, 360, and 330 ng/ml, respectively. The linear dynamic range is greater than three orders of magnitude.     

蔬菜、水果中杀扑磷、伏杀硫磷、亚胺硫磷、蝇毒磷的气相色谱法测定

采用乙腈提取,弗罗里土SPE柱（Florisil）柱层析净化,以DB－5毛细管柱、电子捕获检测器（ECD）的气相色谱（GC）方法,对果蔬中蝇毒磷、杀扑磷、伏杀硫磷、亚胺硫磷农药残留检测进行了系统研究。考察了不同的前处理技术与检测器对定量分析结果的影响。检出限分别为1．7ng、1．6ng、0．66ng、1．5ng,平均回收率为76．5％～117．1％。与常规方法比较,该法灵敏度高,分析时间短,便于这四种目标化合物在高化学背景样品中的准确定量。     

气相色谱法测定香兰素衍生物VND中的残留溶剂

目的用毛细管气相色谱法建立VND中4种残留溶剂的测定方法。方法采用DB-Wax(30m×0.45mm,0.85μm)毛细管柱,载气为氮气,FID检测器。程序升温,柱温:起始温度为35℃,保持17min,然后以30℃/min的速率升至200℃,保持8min。进样口温度:200℃,检测器温度:250℃。分流直接进样,二甲基亚砜为溶剂,正丁醇为内标物,内标法测定残留溶剂的含量。结果在考察范围内呈良好的线性关系(甲醇r=0.9996,异丙醇r=0.9996,乙醇r=0.9995,N,N-二甲基甲酰胺r=0.9995),平均回收率为96%～103%,理论塔板数大于10000,相邻峰分离度均大于1.5,精密度、重复性的RSD均小于3%。结论本法简单、结果准确、重复性好,可同时检测VND中甲醇、异丙醇、乙醇、N,N-二甲基甲酰胺4种残留溶剂。     

酱油中对羟基苯甲酸酯类的测定

对羟基苯甲酸酯是用途广泛的有机合成原料,是目前被广泛使用于食品、化妆品和药品等的防腐抗菌剂。本文所采用的方法参考TGBrr5009．31—2003,对样品前处理和色谱分析方法进行优化改进,通过检测底限、准确度、精密度和线性分析范围进行评价等。该法适用于采用PerkinElmerClams580型气相色谱仪配备FID检测器检测醋、果汁、果酱及含乳饮料等食品中对羟基苯甲酸酯类的检测。     

顶空气相色谱法测定曲安奈德中残留溶剂的含量

目的:建立曲安奈德中有机溶剂甲醇、乙醇、丙酮残留量的测定方法。方法:采用DB-624毛细管色谱柱,FID检测器,二甲基亚砜为溶剂,柱温采用程序升温,进样口温度为200℃,检测器温度为250℃。结果:各待测组分完全分离,线性关系良好,检测限分别为4.01μg/mL、0.40μg/mL和0.10μg/mL,精密度RSD<3%,平均回收率96.26%～107.43%。结论:本法操作简单,结果准确可靠,可用于曲安奈德中残留溶剂的检测。