用二维色谱技术测定聚合反应气体组成

介绍一种无阀切换的二维气相色谱分析方法。采用两根不同性质的色谱柱并联连接，样品分别经两根色谱柱分离后汇合在一起进入同一检测器。一次进样可同时测定Ｈ２、Ｏ２、Ｎ２及Ｃ１～Ｃ３的组分。     

Analysis of nitriles at low parts per million levels by capillary gas chromatography

Two methods have been developed for the determination of trace levels of acetonitrile and propionitrile in light naphthas. One involves clean-up and preconcentration by medium pressure liquid chromatography (MPLC) in which nitriles are concentrated ten-fold while the complex hydrocarbon matris is removed. The concentrated solution is then analyzed by high resolution GC with flame ionization detection. The second method involves direct injection of samples into a capillary GC equipped with chemiluminescence nitrogen detection. The results and repeatability obtained from both methods are comparable. Preconcentration enables identification by GC-MS and simultaneous analysis of other polar species, with no need for selective detectors. Direct analysis is, on the other hand, much less time-consuming and requires less sample.     

Sequential optimisation of the separation of a complex mixture of plastics additives by HPLC with a quaternary gradient and a dual detection system

Summary The separation of two families of plastics additives (phenolic antioxidants and UV absorbers) has been achieved by high performance liquid chromatography with a quaternary gradient. A methodology of separation based on a sequential optimization is described. After a preliminary study of the effects of solvents on retention of compounds, the mobile phase is first chosen for each class of additives (Irganox and Tinuvin), then for the mixture of all the compounds and the separation is finally optimized. The importance of the column phase ratio is also reported. The use of two detectors, UV absorbance and light-scattering, enables all the compounds to be detected. The performance of the detectors has been compared and the effects of the nebulization temperature on the detection of low molecular mass compounds is reported.     

Ion pair generation rates near planar3H and63Ni electron capture detector foils

The ion-pair generation rate (ionization topography) in plasmas from⁶³Ni and particularly Ti³H₄ foils, as used in electron capture detectors, was measured at room temperature using large, parallel plates of low backscattering ability in nitrogen gas of varying density. For one atmosphere pressure, the fall-off of ion pair formation as calculated from the exponential region equalsN ₀·e ^–0.19d for⁶³Ni andN ₀·e ^–1.4d for³H (whereN ₀ is the initial ionization rate immediately adjacent to the foil andd is the distance from the foil in mm). The experimentally measured half ranges (distances from the foil within which 50% of all possible ion pairs are created) are 2.7 mm for⁶³Ni and 0.27 mm for³H. The half ranges calculated from the exponential region where there is less interference from electron backscattering, are 3.7 and 0.5 mm, respectively. The latter values are considered closer to the true, unimpeded ionization topography near planar⁶³Ni and³H foils.Material taken from doctoral thesis     

Stability of the FID sensitivity during an analysis in capillary GC

The sensitivity of an FID may change when the carrier gas flow rate changes during a chromatographic run. Sample parts which are eluted at reduced FID sensitivity produce a reduced peak area, hence are discriminated as compared to other components. Sensitivity changes were studied for hydrogen as carrier gas. For the detector tested, differences in the carrier gas flow rates of 1 ml/min shifted the FID sensitivity by 1 to 5% (depending on the fuel gas supply). Thus the stability of the sensitivity is no longer ensured as soon as the carrier gas flow rate is changed manually or by an automatic programmer during an analysis. Sensitivity drifts may also occur during temperature programmed runs with a pressure regulated carrier gas supply since the gas flow through the capillary drops with increasing temperature. Such shifts in the response became noticeable as soon as relatively high carrier gas flow rates combined with long range temperature programmes were used. The typical patterns of such discriminations are shown, closing with a discussion on the possibilities for minimizing such undesired effects.     

溶液酸度在线检测装置的研制

研制了酸度在线检测装置，并应用于溶液酸度在线检测，溶液酸度在线检测装置，设有防污过滤器，自动采样器，蠕动泵，小型管道ｐＨ传感器和控制电路等，其特点为防污除油，随机自动采样，定时检测，全部管道化，可单独使用和计算机控制系统联网，适用于溶液酸在线分析，测定精度〈ｐＨ０．０５。     

Selectivity enhancement of a metal-sensitive flame ionization detector for capillary gas chromatography

A novel modification of a hydrogen-atmosphere flamo ionization detector (HAFID) is presented which attenuates response to hydrocarbon compounds, significantly enhancing selectivity towards organometallic compounds by more than an order of magnitude. Chromatograms of an organometallic compound test mixture and regular leaded gasoline are presented to depict the specificity of the response.     

Development and validation of an analytical methodology for the determination of p,p′-DDT, p,p′-DDE and p,p′-DDD in fish oil pills

An analytical methodology was proposed and validated to be applied to the determination of p,p′-DDT and its metabolites p,p′-DDE and p,p′-DDD in fish oil. The analytical procedure presented in this paper involves a single-step clean up process prior to the analysis. A solution of 1,2,3,4-tetrachloronaphtalene was used as internal standard.The analytical technique used was gas chromatography coupled to an electron capture detector. Details on the validation process are provided.The limits of detection ranged from 2.6 to 4.7 pg μL^− 1. The BCR 598 standard reference material (cod liver oil) was used to evaluate the performance of the methodology with satisfactory recoveries for all the compounds.The analytes were determined in three different fish oil pills sold in Spain as a supplementary vitamin support. The sum of p,p′-DDT and metabolites was from 13.2 to 51.3 ng g^− 1, the dominant compound being p,p′-DDE.     

端视式全谱直读电感耦合等离子体发射光谱法测定高纯氧化镧中稀土杂质

电感耦合等离子体发射光谱(ICP-AES)测定高纯氧化镧中14个稀土元素杂质,镧对其它稀土元素的光谱干扰比较严重,要求光谱仪单色器有较高的分辨率。使用端视式全谱直读ICP-AES仪,选择测定波长,工作参数优化,讨论了镧和酸度的影响。大部分稀土元素测定使用曲线拟合(FACT)的背景校正方法。该方法的稀土元素氧化物检出限达到3×10-4~0.022 mg.L-1(3σ)。     

Applications of a miniaturized fluorimetric photodiode array detector for capillary liquid chromatography

A high sensitivity, multichannel fluorescence detector with small volume has been developed for capillary column liquid chromatography. Using an intensified linear photodiode array to monitor fluorescence emission, several important mixtures exhibiting native fluorescence have been examined following high efficiency separation on a capillary column. By correlating mass spectral, fluorescence spectral, and retention time data, information of potential utility in the structural elucidation of aromatic molecules contained in complex mixtures can be obtained. Examples include the separation and spectral examination of the polyaromatic compounds in samples of both biological and environmental interest.