Metallic impurities in germanium tetrafluoride and germanium dioxide prepared from it

The composition and contents of metallic impurities (in nonvolatile form) in isotopically unmodified and ⁷⁶Ge-depleted germanium tetrafluoride samples were determined by chemical atomic emission spectrometry. The germanium tetrafluoride samples were then converted to germanium dioxide. The impurity compositions of the resultant germanium dioxide samples were determined by laser mass spectrometry, atomic emission spectrometry, inductively coupled plasma mass spectrometry, and spark source mass spectrometry.     

High-resolution Fourier-transform IR spectroscopic determination of impurities in silicon tetrafluoride and silane prepared from it

The impurity compositions of silicon tetrafluoride and silane prepared from it have been determined by high-resolution Fourier-transform IR spectroscopy. In the spectra of SiF₄ samples differing in purity, we have identified rovibrational bands arising from Si₂F₆O, SiF₃OH, HF, SiF₃H, SiF₂H₂, SiH₃F, CH₄, CO₂, and CO impurities. Their detection limits lie in the range 9 × 10^?5 (CO₂) to 3 × 10^?3 mol % (Si₂F₆O). In the spectra of SiH₄ samples of different purity, we have detected CH₄, CO₂, SiF₃H, SiF₂H₂, and SiF₄ impurities. Their detection limits lie in the range 8 × 10^?5 (CO₂) to 1 × 10^?3 mol % (SiF₄).     

Determination of impurities in high-purity germanium dioxide using atomic emission spectrometry

A technique for the determination of the impurity composition of soluble germanium dioxide and one containing up to 0.1% insoluble in 12 M HCl is described. The technique offers the possibility to control the content of 31 impurities simultaneously after preconcentration with detection limits of about 10⁻⁶ to 10⁻⁸ wt % and with an intralaboratory precision not exceeding 20 rel. %.     

气相色谱法测定茶色素中的乙酸乙酯残留量

本文建立了一个气相色谱法测定茶色素中的乙酸乙酯残留量的方法。方法的回收率为100.1％～101.1％,相对标准偏差为2.0％,检测限为2ng(S/N≥3).测定结果表明:方法具有简单、可靠、快速、准确等特点。     

Determination of methane in ambient air by multiplex gas chromatography

A multiplex gas chromatographic technique for the determination of methane in ambient air over extended periods is reported. A modest gas chromatograph which uses air as the carrier gas was modified by adding a silver oxide sample modulator for multiplex operation. The modulator selectively catalyzes the decomposition of methane in air. The resulting analytical systems requires no consumables beyond power. A profile of the methane concentration in this laboratory was obtained for an 8-day period. During this period, methane concentration varied with an approximately daily period from a low of 1.53 +/- 0.60 ppm to a high of 4.63 +/- 0.59 ppm over the entire 8 days. Some of the measured concentrations are higher than those reported elsewhere indicating the presence of some local source or sources for methane. This work has demonstrated the utility of a relatively simple multiplex gas chromatograph for the analysis of environmental samples. The technique should be applicable to other trace components in air through use of other selective modulators.     

气相色谱法测定异丙醇及影响因素讨论

采用气相色谱法测定脱蜡装置用异丙醇溶液的浓度,内标法定量,简便、快速、准确。对测定结果影响因素进行讨论。     

气相色谱法测定黄酒中的高级醇

本文采用毛细管气相色谱法,以峰面积外标法定量测定黄酒中的高级醇,测得的相对标准偏差为0.01%～1.03%。该方法具有操作简捷、精密度好、准确度高等特点。     

用气相色谱法对水中有机磷农药的测定

本文采用固相萃取法预处理,然后用带有火焰光度检测器(FPD)的气相色谱仪测定有机磷农药。结果表明,该法具有简单、快速、准确的持点。     

气相色谱-质谱测定化妆品中的硝基麝香类化合物

建立了化妆品中5种硝基麝香含量的气相色谱-质谱联用检测方法。采用丙酮/正己烷混合液超声提取化妆品中的硝基麝香,提取液经过浓缩,由气相色谱-质谱联用仪检测,以氘代二甲苯麝香内标法定量。该方法对化妆品中5种硝基麝香的加标回收率在85.21%~110.2%之间,相对标准偏差(RSD)不大于7.15%,在50μg/L~5000μg/L范围内呈现良好的线性关系,灵敏度高,最低检测限分别达到20~50μg/kg;选择性好,能有效消除复杂基体干扰。可用于常见化妆品中硝基麝香类化合物含量的检测。     

超声波提取—气相色谱法测定土壤中有机氯农药残留

本文采用超声波萃取-气相色谱法测定土壤中八种有机氯类农药残留,方法简单、快速、灵敏度高,检测限在0．70-2．4μg/L之间,回收率在81．4—105．5％之间,精密度在4．08—8．52％之间。     

气相色谱法测定饮用水源中四氯化碳

基于FYGC-2000(C)气相色谱仪气相色谱法测定了饮用水源中四氯化碳含量,所得的回归方程为=79477X-6097.8相关系数r=0.9998,2μg/L和10μg/L两个浓度电位的精密度试验中的所得标准偏差分别为3.3778％和0.742％.在加标回收率测试中加标量分别为2 ug/L和5 ug/L时,回收率在99...     

顶空气相色谱法测定利奥西呱原料药中9种残留溶剂的含量

建立同时测定利奥西呱原料药中残留溶剂甲醇、异丙醇、二氯甲烷、正己烷、乙酸乙酯、六甲基二硅醚、三乙胺、甲苯与N,N-二甲基甲酰胺残留量的方法。采用顶空进样气相色谱法,以二甲基亚砜为溶剂,外标法计算残留溶剂量。9种残留溶剂色谱峰的理论板数均10 000,相邻峰的分离度均1.5,在考察的浓度范围内各溶剂线性关系良好(r=0.998 2~0.999 7);RSD10%;平均加标回收率为90.86%~105.01%。各残留溶剂的检测限和定量限分别为0.000 025%~0.002 6%,0.000 051%~0.008 8%,均低于《中国药典》规定。利奥西呱原料中检出甲醇、正己烷、乙酸乙酯与DMF残留,但均未超过限度,其余溶剂未检出。该方法操作简单、方法灵敏、结果准确,可用于利奥西呱原料药中残留溶剂检测。     

Determination of elemental impurities in plastic calibration standards using laser-induced breakdown spectroscopy

Dual-energy computed tomography (CT) scanning is a rapidly emerging imaging technique employed in nondestructive evaluation of various materials. CT has been used for characterizing rocks and visualizing multiphase flow through rocks for over 25 years. The most common technique for dual-energy CT scanning relies on homogeneous calibration standards to produce the most accurate decoupled data. However, the use of calibration standards with impurities increases the probability of error in the reconstructed data and results in poor rock characterization. Laser-induced breakdown spectroscopy was used to determine impurity concentration in a set of commercially purchased calibration standards used in dual-energy scanning for material identification with coal samples. Two calibration models were developed by using univariate calibration with the internal ratio method and multiple linear regression. Seven elements (Al, Fe, Mg, Na, Ni, Sr, and Ti) were examined in five different samples containing varying amounts of each ion to compare calibration from univariate data analysis and from multivariate data analysis. The contaminant concentrations were also measured by a commercially available inductively coupled plasma optical emission spectroscopy instrument, and the data were used as a reference in developing calibration curves for a modified version of the single linear regression model and the multiple linear regression model.     

Removal of carbon tetrafluoride from nitrogen trifluoride by gas hydrate crystallization

This paper examines the separation of gas mixtures based on nitrogen trifluoride and carbon tetrafluoride by different versions of gas hydrate crystallization. We calculate the distribution coefficient and separation factor of the major components of the mixture in the temperature range 253–273 K for different pressures and gas mixture compositions. The results demonstrate that gas hydrate crystallization ensures efficient separation of mixtures containing nitrogen trifluoride and carbon tetrafluoride. Directional crystallization allows nitrogen trifluoride to be separated more completely, whereas crystallization at constant pressure ensures a larger yield of the purified material.