光催化氧化丙烯产物的气相色谱分析

建立了光催化氧化微量丙烯所产生的CO2和H2O的气相色谱分析检测方法.CO2通过一个装有Ni催化剂的转化炉加氢转化成CH4,H2O通过一个CaC2反应管转化成C2H2,从而可以利用氢火焰离子化检测器（FID）进行微量分析.利用该分析方法能对反应生成的CO2进行定性和定量分析,对反应生成的H2O进行定性分析.实验证明该分析方法的准确度、精密度和灵敏度都能满足实验的要求.有氧气的存在下会出现＂鬼峰＂,文中对这一现象进行了讨论.     

气相色谱法测定洗涤剂用脂肪醇

建立了一种快速、准确测定洗涤剂用脂肪醇的气相色谱分析方法。采用气相色谱和质谱联机方法对洗涤剂用脂肪醇进行了定性分析,采用气相色谱法对洗涤剂用脂肪醇进行了定量分析。用正构脂肪醇对定量分析方法进行了考察,其结果的相对标准误差为2．2％。用气相色谱确定了每个组分的含量,定量结果的相对标准偏差小于2．6％。分析结果为装置操作优化及改进洗涤剂脂肪醇的正构度提供了技术支持。     

近两年国内气相色谱的应用进展(Ⅱ)

对近两年国内各个领域的学者在气相色谱方面的研究和应用作了综述,本综述分3部分叙述,本篇为第Ⅱ部分,包括：5．中药中有效成分的气相色谱分析。6．西药的气相色谱分析。7．气相色谱在食品中有害物质分析的应用。     

天然气密度计算结果的不确定度分析比较

天然气的密度通常采用气相色谱分析方法得到。分析了这种方法计算密度结果的不确定度,并与SY/T6143《天然气流量的标准孔板计量方法》中经验公式计算的密度不确定度进行比较。结果表明:按照SY/T 6143标准计算的密度不确定度与天然气压力和温度有关,而采用气相色谱分析方法计算的密度结果的不确定度仅与天然气组分含量有关;SY/T 6143标准所计算的密度不确定度结果更可靠些。     

气相色谱法测定饮料中的苯甲酸

采用三氟化硼一甲醇衍生化气相色谱法 ,对饮料中苯甲酸的测定进行了研究 ,建立了一种饮料中苯甲酸的气相色谱分析方法 ,经精密度、准确度测定 ,结果令人满意     

安眠镇静药物的串联质谱分析方法

气相色谱以及气相色谱／质谱联用经常被用来分析生物体液样品中的药物。用这些方法分析时，需要在色谱分析前，进行长时间的样品制备和衍生化过程。本文描述了用地识别１６安眠镇静药物的ＥＩ／ＭＳ／ＭＳ过程，并且对两例服毒自杀者的尿样进行了检测。     

超临界CO2萃取柚子种子油及脂肪酸的气相色谱分析

应用超临界CO2萃取技术萃取柚子种子油,并对种子油进行了气相色谱分析。研究了萃取压力、温度和时间对柚子种子油得率的影响。当萃取温度为45℃,萃取压力35 MPa,萃取时间150 min时,柚子种子油的提取率为44.58%。气相色谱分析表明,柚子种子油中主要含有各类不饱和脂肪酸,其中亚麻酸、亚油酸、油酸的相对含量分别为4.40%、34.56%和27.19%。通过对柚子种子油的分析,为其进一步开发利用提供科学依据。     

煤焦油中洗油组分气相色谱分析方法的建立

建立了一种分析煤焦油中洗油组分的气相色谱分析方法.以无水乙醇做溶剂,SE-52弱极性的毛细管色谱柱和氢火焰离子检测器进行分析.在用标准试剂配制的已知各组分浓度的模拟洗油的分析中,得到了效果最好的程序升温方式.在对每种标准试剂制作色谱分析工作曲线的基础上,对实际洗油进行了分析,得到了很好的结果.     

气相色谱法测定有机锡化合物的样品前处理技术

用气相色谱分析有机锡化合物，前处理技术是降低检出限、提高灵敏度的前提和重要途径，也是研究的重点和难点。本文就气相色谱分析有机锡化合物时样品的制备与储存，样品的萃取、衍生、净化等前处理技术作了较为系统的介绍。     

噻吩产物的气相色谱分析

含硫有机化合物的气相色谱分析早有报道.但是适用于呋喃噻吩产物气分析,尤其是有关的定性定量用参考数据未见报道。本文介绍了用气相色谱分析呋喃制噻吩产物方法,得到满意结果. 实 验 部 分 气相色谱仪:SP-2305E型。N_2为载气.为避免产物气中大量H_2S和H_2O的干扰,采用FID检测器。用APPLE-Ⅱ微机与之联机进行色谱数据的采集和处理.     

Ion-exchange chromatography of anions with tiron as eluent

The characteristics of Tiron (1,2-dihydroxybenzene-3,5-disulfonic acid and its sodium salt) solution as an eluent for anions in ion-exchange chromatography was investigated with conductivity and UV absorbance detectors. Tiron (acid and sodium salt) has such a strong affinity for the anion exchanger that the concentration in the eluent can be made lower than that of benzene carboxylates, such as phthalate, which have been used similarly. Tiron acid exhibited an unusual effect which increased the sensitivity with a conductivity detector. The water dip was not observed, and a big ghost peak appeared near the sulfate peak. Tiron salt did not produce a ghost peak, and was better for highly sensitive detection in indirect photometric chromatography than phthalate, because of a better balance between UV absorptivity and elution ability. Because Tiron forms stable chelates with many metal ions, pretreatment with a cation-exchange resin is necessary for real samples such as tap water.     

Characteristics and application of an electrochemical concentration modulator in correlation chromatography Part 1. Characterization

An electrochemical concentration modulator is tested for its applicability as an injection device in correlation chromatography. The use of conventional signals to control the potential of the working electrode in the modulator cell produces ghost peaks in the correlogram. The effects of the modulation interval, the time scale of the control signal and the concentration of an electroactive model compound (hydroquinone) on the pattern of the ghost-peak intensities are described. A simple model, based on the combined action of a charging-current time constant and the relative position of the half-wave potential in the modulation interval, is used to describe the result on the concentration profile of the analyte. The mechanisms responsible for ghost peak generation are described.     

Cholesterol-rich membrane coatings for interaction studies in capillary electrophoresis: application to red blood cell lipid extracts

The purpose was to develop a stable biological membrane coating for CE useful for membrane interaction studies. The effect of cholesterol (chol) on the stability of dipalmitoylphosphatidylcholine (DPPC) and sphingomyelin (SM) coatings was studied. In addition, a fused-silica capillary for CE was coated with human red blood cell (RBC) ghost lipids. Liposomes prepared of DPPC/SM with and without chol or RBC ghost lipids were flushed through the capillary and the stability of the coating was measured electrophoretically. Similar mixtures of DPPC/SM with and without chol were further studied by differential scanning calorimetry. The presence of phosphatidylcholine as a basic component in the coating solution of DPPC/SM/chol was found to be essential to achieve a good and stable coating. The results also confirmed the stability of coatings obtained with solutions of DPPC with 0-30 mol% of chol and SM in different ratios, which more closely resemble natural membranes. Finally, the electrophoretic measurements revealed that a stable coating is formed when capillaries are coated with liposomes of RBC ghost lipids.     

Rapid determination of short-chain fatty acids in colonic contents and faeces of humans and rats by acidified water-extraction and direct-injection gas chromatography

Short-chain fatty acids (SCFAs) have attracted much attention recently because of their positive physiological effects. In this work, a rapid and reliable gas chromatographic method for determination of eight SCFAs, in colonic and faecal samples from rats and humans has been developed and validated. The methodology involves extraction of the SCFAs in water before a direct injection procedure on a FFAP capillary column. A stock standard solution containing acetic acid, propionic acid, n-butyric acid, i-butyric acid, n-valeric acid, i-valeric acid, n-caproic acid and n-heptanoic acid was prepared and used. A high linearity (r2 > 0.9990), low quantification limit (2.38-30.14 microm) and high recovery for most acids were obtained. Acidification of faecal samples was found to be crucial for quantitative determination of the SCFAs, and adjustment of pH to 2-3 was regarded as necessary. Glass wool inserted in the glass liner of the injection port proved effective in preventing the contamination of the column by non-volatiles, and 12% formic acid reduced the ghost peak that appeared gradually after several injections. After validation, the methodology was applied on two faecal samples from rats fed diets containing different amount of dietary fibre and one faecal sample from human fed a normal diet to test the accuracy of the developed method.     

QUENCHING OF SINGLET OXYGEN BY HUMAN RED CELL GHOSTS

Time resolved measurements of singlet oxygen phosphorescence at 1270 nm were made from unsealed red cell ghosts, labeled with 5-(N-hexadecanoyl)aminoeosin and suspended in deuterium oxide buffer. The singlet oxygen emission lifetime was long, 23 +/- 1 microseconds. The lifetime of the singlet oxygen phosphorescence from intact unsealed ghosts was not a measure of the singlet oxygen lifetime within the red cell ghost membrane, however. The prolonged singlet oxygen emission was due to singlet oxygen escaping from the thin membrane into the buffer, since the emission lifetime was significantly shortened by adding azide ion or water to the deuterium oxide buffer. The lifetime of singlet oxygen within the red cell ghosts membrane was estimated by dispersing the ghosts with detergent and then measuring the singlet oxygen lifetime in deuterium oxide buffers containing various dilutions of the dispersed ghosts. Apparent singlet-oxygen quenching constants were measured using four different photosensitizing dyes and two different detergents. The apparent quenching constant was independent of the dye used, but varied significantly with different detergents. Extrapolation of this data to "100%" ghost concentration gave a singlet oxygen lifetime from 24 and 130 ns. A ghost concentration of "100%" was defined as that concentration of red cell ghost molecules which would be contained within a red cell ghost membrane pellet containing no buffer solutions. Most of the singlet oxygen quenching was due to proteins. Lipids extracted from red cell ghosts accounted for only 2-7% of the total singlet oxygen quenching.     

A comparison of photopeak area computation methodologies

The accuracy and precision of photopeak area calculation methods has been studied by comparison of a digital method of computation with the fitting of a mathematical function to the data. In the present study, peak areas for 16 replicate photopeaks were computed both by the total peak area method any by the peak fitting method of program SAMPO. Both methods worked well with the fitting method showing somewhat smaller spread in the results.     

Computer analysis of weak spectral components in gamma-ray spectra

Optimal accuracy and precision for relatively weak gamma-ray spectral components were the goal of this study. Such components exhibit small photopeaks situated on large Compton continua; an example of this situation often occurs in measurement of low levels of mercury in biological samples. In this study, four calculational methods were tested: peak area, spectrum stripping, least squares, and peak fitting. All the methods were reasonably accurate on the average. Of significance here is the spread of individual results; the least squares results provided the smallest spread in results, but stripping did almost as well. The other two methods displayed poor precision. In conclusion, the least squares technique gave the best results in terms of accuracy, precision, and ease of application. Work performed at National Bureau of Standards, Washington, D. C., USA.     

A full-scale tracing study of “ghost peaks” encountered in impurity analysis of budesonide based on experimental operation inspection-liquid chromatography/mass spectrometry fingerprint-mechanism based stress studies integrated strategy

Budesonide is an active pharmaceutical ingredient used in various dosage forms of finished products for the treatment of asthma. During the process of drug development, unbiased analysis of related substances is of utmost significance for both pharmaceutical research and quality control purposes. In this work, the official method documented in the United States Pharmacopoeia was selected to determine the related substances of budesonide considering the pros and cons of critical chromatographic parameters, compared to the European Pharmacopoeia. In doing so, several unpredictable interference peaks, namely “ghost peaks”, were observed occasionally during analysis. A strategy that integrated information derived from experimental operation inspection, liquid chromatography/mass spectrometry fingerprint analysis, and mechanism-based stress studies was then proposed for comprehensively and quickly exploring those non-degradable and degradable peaks. Some ghost peaks were found to originate from nylon syringe filter, illumination, and alkali borosilicate glass high-performance liquid chromatography vials. Besides, degradation pathways under alkaline conditions were also unraveled through liquid chromatography-mass spectrometry qualitative analysis. Overall, an optimization of the analytical methodology based on the United States Pharmacopoeia for its application in impurity analysis of budesonide and corresponding formulations was carried out with the design of experiments, by which “ghost peaks” could be suppressed or prevented. The results obtained herein are not only crucial to studies on budesonide's stability or degradation kinetics but also contribute to clarifying the impurity research of other drugs.     

Improved computer algorithm for characterizing skewed chromatographic band broadening : II. Results and comparisons

A newly developed method using an exponentially modified Gaussian peak shape model produces results that are more precise and less subject to baseline noise than previous methods for characterizing chromatographic band broadening. The method requires only precisely measurable experimental peak parameters: peak retention time, peak height, peak area, and peak centroid (first moment). Accuracy and precision of the new method were compared with other digital approaches by using computer-synthesized peaks and experimental chromatographic data from many HPLC columns. The proposed method offers a reasonable compromise between accuracy, precision, and convenience. A rapid visual estimate of peak skew can be made by inspecting peak shape and referring to a calibration plot involving peak parameters. Peak variance and skew data from this method are also useful for finding column dispersion corrections in size-exclusion chromatography calibrations.