快速测定含水溶液中乙醇的氧同位素比值（英文）

近年来,乙醇的氧同位素比值(δ~(18)O)在果汁和饮料酒真实性鉴别中起着重要作用,利用该指标可检测产品中的外源水、追溯产品的产地。本工作采用多孔聚合物气相色谱柱实现了水与乙醇的在线快速分离,建立了溶剂稀释后直接用气相色谱-裂解-稳定同位素比值质谱(GC-TC-IRMS)测定溶液中乙醇δ~(18)O值的方法。实验结果表明,该方法可排除水对乙醇δ~(18)O分析的干扰,乙醇浓度在1%~100%时测定稳定性良好,在不同水溶液中乙醇δ~(18)O的测定值保持一致;乙醇δ~(18)O值重复性和再现性的标准偏差均优于0.5‰,并通过欧盟实验室间能力验证(FIT-PTS)证明了方法的准确性。该方法具有样品用量少(仅需70~200μL)、分析速度快(约18min)、操作简单方便等特点,可为乙醇δ~(18)O在果汁和饮料酒真实性领域的研究与应用提供方法参考。     

固相萃取净化-气相色谱法同时测定茶叶中16种有机氯、拟除虫菊酯农药残留

对茶叶中多种农药残留气相色谱测定方法做了改进,建立了茶叶中16种农药残留同时测定的新方法.待测组分经提取、净化后进行气相色谱测定.淋洗液为石油醚和乙酸乙酯混合溶液,对两者的比例作了优化(石油醚:乙酸乙酯=7∶3,v/v).16种农药残留组分的标准加入回收率为92.7%～102.9%,检出下限为0.1～3.3μg/kg,相对标准偏差为3.4%～8.9%(0.04～0.2μg/kg,n=5),能满足出口企业对产品质量控制的要求.     

气质联用法测定鸡蛋中残留三聚氰胺的研究

目的建立了气相色谱-质谱法测定鸡蛋中残留三聚氰胺(Melamine)含量的分析方法。方法样品经甲醇-氨水(95:5)溶液超声提取,离心后,取其上清液真空挥干,经硅烷化衍生后,用气相色谱-质谱法测定,并以苯代三聚氰胺(Benzoguanamine)为内参照。结果该方法可实现目标物与杂质的基线分离,内参照可对检测质量进行监控。标准曲线的回归方程为Y=16732.77X-5313.914,R=0.9960,线形范围为0～8.0mg/kg;检出限为0.05mg/kg,重现性和精密度RSD分别为1.97%和0.46%,样品的加标回收率在98.00～104.85%。结论该方法简便、快速、灵敏、准确,适合鸡蛋中残留三聚氰胺的确证和定量测定。     

离子对液相色谱法测定柴枳四逆散中辛弗林的含量

目的:建立测定柴枳四逆散中辛弗林含量的方法。方法 :采用高效液相色谱法,色谱条件为Fortis C18色谱柱(4.6×250mm,5μm),流动相为甲醇-磷酸二氢钾溶液(43:57),流速为1.0ml·min-1,柱温:30℃,检测波长为275nm。结果:辛弗林在1.82³6.40μg·ml-1(r=0.9999)浓度范围内有良好的线性关系,平均加样回收率为98.0%,RSD为1.50%。结论:本方法准确,重复性好,可用于柴枳四逆散中辛弗林的测定。     

GC-MS/MS方法测定大米中农药残留杀虫环

目前测定大米中杀虫环的农药残留多采用气相色谱方法,样品前处理时试剂需要提纯,既危险又繁琐,目标峰还存在干扰,影响定性;采用液相色谱和液质联用的方法处理样品需使用固相萃取柱,增加了检测成本,也比较费时间,液质联用方法虽然定性比较准确,但其检出限比较高。本文采用溶剂萃取方法处理样品,气质质联用仪测定,样品处理简单,耗材成本低。本方法对仪器条件进行了优化,具有较好的重复性和较低的检出限。测定重复性的标准偏差(RSD)达到4.1%,检出限达到0.8μg/kg,由于本方法较低的检出限,对研究大米中农残杀虫环的降解过程将提供有力的检测手段。     

异硫氰酸苯酯柱前衍生法测定安尿通中3种氨基酸含量

本文介绍安尿通中 3种氨基酸的柱前衍生后以RP -HPLC测定的方法。PhenomenexLunaODS(4 .6× 2 5 0mm)色谱柱 ,移动相A∶0 . 1mol·L 1醋酸钠溶液 (pH6 . 5 ) -乙腈(93∶7) ,移动相B :水和乙腈 (2 0∶80 ) ,梯度洗脱检测波长是 2 5 4nm ,柱温 4 0℃ ,氨基酸的重复性是 99. 2 %～ 99 .5 %。     

毛细管气相色谱法分析土壤中苹果酸、柠檬酸和丙二酸

采用毛细管气相色谱法对土壤样品中苹果酸、柠檬酸、丙二酸进行了分析,通过将有机酸进行酯化衍生化前处理,增加了试样中有机酸的挥发性,以适应气相色谱法的检测要求,并对这些有机酸的色谱测定条件进行了优化选择。实验证明,该方法重复性好,精密度高。     

GC和GC/MS法测定洗涤及化妆用品中二噁烷残留量

建立了用毛细管气相色谱配氢火焰离子化检测器测定洗涤和化妆品中二噁烷的方法。样品用适量的水提取,将二噁烷完全溶解。加入1.0 g氯化钠固体,产生“盐析”效应,以增加二噁烷在顶空瓶中的浓度。70℃时于顶空瓶中混合40 min,达到气液平衡状态,取上清气体直接注入气相色谱进行分析。采用程序升温,用保留时间定性,外标法定量。并进一步采用气相色谱-质谱定性定量。该方法测定二噁烷含量具有较高的准确度。二噁烷回收率为98.8%~108.5%,相对标准偏差2.95%~7.61%,最低检出限为2.5mg/kg。     

水源地5种阴离子的同时测定

建立用单柱阴离子色谱测定水源地水中的F~-、CI~-、NO_2~-、PO_4~(3-)、NO_3~(-)5种阴离子的方法。采用NJ-SA-4A阴离子交换柱、0.35 mmol/L NaCO_3和0.05mmol/L NaHCO_3混合溶液为流动相、电导检测器在11min内完成5种阴离子的测定。该法具有良好的线性相关性和重复性(相对标准偏差2.18%～4.33%),回收率为93%～109.5%。方法简便实用,用于实际样品分析,所得结果令人满意。     

气相色谱法测定食品中丙酸钠 丙酸钙方法的改进

建立使用填充柱(填装涂布5%(m/m)DEGS+1%磷酸固定液的(60~80目)Chromosorb W/AW DMCS,2 m*3 mm)代替使用昂贵的国外Porapak系列高分子聚合物色谱柱测定食品中丙酸钠、丙酸钙的气相色谱法。结果:本法在丙酸盐浓度0~250 mg/L范围内呈良好线性关系,相关系数r大于0.999,方法平均回收率95%~105%,进样精密度实验的RSD(%)值均小于3.0,方法的检出限为0.012 g/kg,满足检测要求。     

Investigation on the influence of various welding parameters on the arc thermal efficiency of the GTAW process by calorimetric method

Arc efficiency of Gas Tungsten Arc Welding (GTAW) was determined by calorimetric method. A water-cooled anode calorimeter was designed and manufactured to measure the arc thermal efficiency, which was determined as a function of current, arc length, polarity and gas flow rate for GTAW of mild steel. With Direct Current Electrode Negative (DCEN) polarity and 5 mm arc length, a thermal efficiency of 67±4% was obtained, which was independent of the welding current. With Direct Current Electrode Positive (DCEP) polarity and 5 mm arc length, arc thermal efficiency was determined as 52±4%. The experimental data show that the arc efficiency decreases from 67% to 58% and 51% as the arc length increases from 5 mm to 11 and 17.5 mm, respectively. The experimental results also show that the arc efficiency is not significantly affected by the shielding gas flow rate.     

Rapid Isothermal Gas Chromatography‐Mass Spectrometry Method for Validating a Small Ion Mobility Spectrometer Sensor

Abstract

A fast and reproducible isothermal gas chromatographic‐mass spectrometric method for validating a small ion mobility spectrometer (IMS) sensor for detection of gaseous volatile organic compounds (VOCs) is presented. This method utilizes an automated cyclic valving (CV) sampling technique coupled to a gas chromatograph‐mass spectrometer (GC/MS) in selected ion monitoring (SIM) mode (CV/GC/MS/SIM). The sampling time is considerably reduced by operating the GC isothermally at 300°C. This approach provides rapid measurements with 15 times more data points than the conventional GC/MS methods in which the column temperature is ramped, then cooled before the next sample can be injected. With the mass spectrometer operated in SIM mode, pre‐selected ions that represent the primary quantitation and secondary ions of toluene and a BTX (benzene, toluene, o‐, m‐, and p‐xylene) mixture were monitored and their corresponding breakthrough curves for flow through partially saturated soil columns were generated. The small variation in measured steady state mean concentrations (SSMC) from run to run demonstrates the reproducibility of this new method. A comparison of the transient concentration profiles of toluene from a BTX mixture and toluene alone obtained under identical test conditions shows a linear correlation with R²=0.997. This result suggests that the new method can be used to analyze and quantify some mixtures of co‐eluting gaseous analytes.     

火焰原子吸收光谱法测定茄子中钙镁

本文建立悬浮液技术及非完全消化 -火焰原子吸收光谱法快速测定茄子中钙、镁的分析方法。试验表明 ,在悬浮液中加入适量盐酸可显著提高钙、镁的吸光度。对盐酸溶液用量、化学干扰、背景吸收干扰、试液与空白溶液物理性质的一致性进行考察。测定结果的RSD小于 1.1% ,测定结果与灰化法一致 ,相对误差小于± 1.0 %。     

High GVF and low pressure gas–liquid two-phase flow measurement based on dual-cone flowmeter

Parameter measurement of gas–liquid two-phase flows with a high gas volume fraction (GVF) has received great attention in the research field of multiphase flow. The cone meter, as a new proposed differential pressure (DP) meter, is increasingly being applied in flowrate measurement of gas–liquid two-phase flow. A dual-parameter measurement method of gas–liquid two-phase flow based on a dual-cone meter is proposed. The two-phase flow is investigated in a horizontal pipeline with high GVF and low pressure, and exists in the form of annular flow. By adding a second cone meter, both gas mass fraction (GMF) and mass flowrate are measured. The pressure drop performances of five different sized cones have been discussed to make a cooperating cone selection and efficiently position the dual-cone in the pipe. Dual-cone flowmeter experiments of 0.45 and 0.65 equivalent diameter ratio combination, and 0.65 and 0.85 equivalent diameter ratio combination are respectively carried out to analyze the linearity of two-phase flow multiplier with Lockhart–Martinelli parameter and obtain the dual-parameter measurement results. The relative experiment error of GMF, gas mass flowrate and total mass flowrate are respectively within ±7%, ±5% and ±10%. The relative error of the liquid phase is within ±10% when the liquid mass fraction is beyond 40%. The experimental results show that it is efficient to utilize this dual-cone method for high GVF and low pressure gas–liquid two-phase flow measurement.     

采用裂解气相色谱/质谱法研究双酚A环氧树脂结构

采用裂解气相色谱/质谱联用方法对不同品种和牌号的双酚A环氧树脂进行分析研究。选择550℃裂解,其裂解产物通过SE～54高效毛细管柱分离和质谱鉴定,提供了有关环氧树脂的特征结构信息。通过对总离子流图中裂解碎片峰峰面积比值的计算,可初步鉴定7种不同牌号的环氧树脂。此方法,具有样品无需前处理,作量少,对应性强,灵敏度高等特点。     

Laboratory-scale apparatus for the characterization of gas-phase dioxin adsorption

Zeolites are reported as selective adsorbents for the preconcentration of dioxin congeners for emission monitoring at stationary sources. This article involves the development of a laboratory-scale apparatus to characterize gas-phase dioxin adsorption on zeolites and thermal desorption. The laboratory-scale apparatus prepared stable levels of dioxin in a nitrogen flow and in-line adsorption/thermal desorption coupled to a gas chromatograph–mass spectrometer. The apparatus takes into account the low-volatility of the dioxins for their transport in the carrier gas and the possible high temperatures used for zeolite desorption. The apparatus functionalities, such as in-line concentration measurement by a sampling loop and gas chromatograph–mass spectrometer and breakthrough measurement during in-line adsorption, were validated. The generator delivers a stable 2,3-dichlorodibenzo-p-dioxin concentration of 304 ± 6 µg/m³ over 20 days. Two methods, weighing a vial and mass analysis of the sampling loop, were employed for measuring the concentration provided results that were in good agreement. Preliminary gas-phase adsorption experiments have been carried out without any memoryw effects in the valves and transfer lines. The dioxin concentration generated and large diameter of the beads led to low adsorption efficiency of dioxin on FAU13X Na-type zeolites due to a low micropore accessibility.     

A V-Cone meter measurement correlation in low pressure wet gas based on Chisholm model

To gain a deeper understanding of the performance of V-Cone meter in low pressure wet gas measurement, the over-reading of the V-Cone meter was experimentally investigated in the present study. The equivalent diameter ratio of the V-Cone meter is 0.55. The experimental fluids were air and tap water. The operating pressure and the gas volume fraction ranged from 0.1 MPa to 0.4 MPa and 97.52%–100%, respectively. The results showed that the existing V-Cone wet gas correlation, which was developed for the medium and high pressure wet gas cannot be well extended to the low pressure conditions. The Chisholm exponent monotonically decreased with the ratio of liquid-to-gas mass flow rate increasing, and was almost not affected by the gas to liquid density ratio and the gas densiometric Froude number in the present test ranges. A measurement correlation dedicated for the low pressure wet gas was developed. In the present cases, the relative deviation of the gas mass flow rate predicted by the new correlation was within ±4.0% and ±3.0% under the 95% and 90% confidence level, respectively; the average relative deviation was 0.046%. Our results provide insights into the measurement performance of V-Cone meter in low pressure wet gas and may help to develop a more comprehensive wet gas correlation.     

氮中氢气体标准物质性能的评价方法

本文介绍了用北京赛洋技贸有限公司QSP—KI型气敏色谱仪和日本岛津GC-8A气相色谱仪（TCD）分析氮中氢气体标准物质的实验方法和条件。用所建立的分析方法和条件分别对氮中氢系列标准气体色谱分析方法的精密度、方法的线性度进行了考察。QSP—KI型气敏色谱仪在氮中氢气体标准物质量值（1～10）×10^-6mol／mol范围内,获得的方法的精密度≤±0．6％。GC-8A气相色谱仪在量值（10×10^-6～50％）mol／mol范围内,其方法的精密度〈±0．5％。二者的最大线性误差≤±2．0％。文章中还对重量配制法、容量法、色谱法的比对误差进行了考察,同时给出了氮中氢标准气体的性能评价（均匀性、稳定性、随压力的稳定性变化）的实验结果。     

关于气相色谱仪进样器系统的性能验证探讨

通过解析国内外标准对气相色谱仪进样器系统性能验证的方法,结合国内气相色谱仪计量现状,设计了一套气相色谱仪进样器系统性能验证方案。对方案进行了验证试验,并就试验中遇到的一些问题进行了探讨。     

DETERMINATION OF CINACALCET HYDROCHLORIDE BY CAPILLARY ELECTROPHORESIS WITH PHOTODIODE ARRAY DETECTION

This article reports a validated stability-indicating capillary electrophoresis method using a photodiode array detector at 220 nm for the determination of cinacalcet hydrochloride. The best electrophoretic separation between the analyte and internal standard (lamotrigine) was achieved within 5 min in a deactivated fused silica capillary (55 cm effective length × 75 µm internal diameter) maintained at 24°C using a background electrolyte solution consisted of phosphate buffer (50 mM, pH 6.4):methanol (95:5, v/v) at a separation voltage of 30 kV. The linear range of the method was 0.5–30 µg/mL (r = 0.9999) with limits of detection and quantitation of 0.1 and 0.5 µg/mL, respectively. The assay precision and accuracy were favorable as the relative standard deviations did not exceed 1.09%, and the recovery values were 98.99–100.33 ± 0.19–1.09%. The induced degradation products, when any, did not interfere with the detection of analyte. The proposed method was successfully applied for the determination of cinacalcet hydrochloride in bulk and pharmaceutical formulations; the percentage recovery values were 98.16–102.00 ± 0.24–1.08%. The results demonstrated the value of the method.