色谱气相分析法判定变压器内部故障

1色谱分析变压器油故障的分类 色谱分析变压器油溶解气体分析法(简称DCA)是诊断器身故障的有效技术措施,变压器油中溶解气体经脱气、检测(采用气相色谱法),在得到一组数据后按图1所示步骤进行工作.

气相分子吸收光谱法在水质无机检测中的应用

气相分析吸收光谱法是基于朗伯-比尔定律,通过将被测组分分解成相应气体分子而载入测量系统,测定其对特征光谱的吸收及吸光强度来进行定性定量分析的方法。目前在水质无机检测中应用较广。本文对近年来国内气相分子吸收光谱法在该领域的应用进行了研究,并对以后的发展提供了方向。

响应面法优化樟树籽油脂质体的制备工艺

采用薄膜分散法结合动态高压微射流技术制备樟树籽油纳米脂质体,以包封率及粒径为主要指标,考察各因素对樟树籽油脂质体制备的影响,建立以癸酸、月桂酸为指标的包封率测定方法,薄膜分散-动态高压微射流技术制备樟树籽油脂质体最佳工艺为大豆卵磷脂质量浓度3g/100mL、大豆卵磷脂与樟树籽油质量比3:1、大豆卵磷脂与胆固醇质量比6.7:1、磷酸缓冲溶液pH7.0、吐温80加入量占卵磷脂质量的24.2%、微射流120MPa处理两次,此条件下包封率可达(91.8±3.7)%,平均粒径达(107.1±8.6)nm。

定量分析被吸附的黄药捕收剂的方法

用顶空分析气相红外光谱法(HAGIS)对方铅矿/黄药体系中吸附在矿物表面上的黄药进行了定量分析。考查了4个可能的标准异丙基黄原酸钠、异丙基黄原酸铅、与异丙基黄原酸钠搅拌过的方铅矿和与异丙基黄原酸钠搅拌过的硫化铅矿石。对4个体系都得到了线性标定曲线。试验结果表明,用矿石作为标准具有实用价值。

变压器铁芯接地故障的分析及处理

铁芯多位置接地是变压器常见的故障之一,文章对故障特征、原因及分析检查方法进行了详细的阐述,并使用常见的几种故障问题分析法对数据进行了比较。然后对一个在变压器运行过程中发生的铁芯接地故障进行了分析,根据其气相和对故障点的检查和处理,指出了故障产生原因及应作的预防措施。

海南岛113种代谢遗传病的筛查

目的 调查海南岛新生儿及儿童代谢遗传病的发病情况 ,了解其种类及发生率。方法 :采用气相——质量色谱分析法出生 5— 10天的新生儿至 14岁以下高危儿童的尿液检测其代谢产物。结果 :检测新生儿及儿童共111例 ,阳性率为 3.6 0 (4/111)。共分两组 ,高危儿为一组阳性 3例 ,阳性率为 2 3.0 8 (3/13) ,对照组 ,阳性 1例 ,阳性率为 1.0 2 (1/98)。两组对比存在显著差异。结论 :采用气相—质量色谱分析法 ,只需少量尿液即可明确诊断113种先天性代谢性疾病 ,可以早期发现、早期诊断、早期预防、早期干预 ,从而避免造成体格发育落后和神经系统发育迟滞 ,如智力障碍。

甲霜灵在水中的光化学降解

该文阐述了水中甲霜灵残留量的气相色普仪分析检测方法,研究了两种不同光源对甲霜灵在水中光化学降解的影响。结果表明,当甲霜灵添加浓度在0.05mg/L～5mg/L时,回收率变幅为83.85%～91.80%,相对标准偏差在2.50%～6.44%,在不同光源照射下,甲霜灵于纯水中的光解速率有显著的差异,表现为高压汞灯>太阳光。

Determination of constituents of essential oil from Angelica sinensis by gas chromatographymass spectrometry

Gas chromatographymass spectrometry (GC-MS) coupled with chemometric resolution upon two- dimensional data was employed to analyze the constituents of essential oils of Angelica sinensis. Constituents in essential oils of Angelica sinensis root were identified by GC-MS with the help of subwindow factor analysis (SFA) method resolving two-dimensional original data into mass spectra and chromatograms. 76 of 97 separated constituents in essential oil of Angelica sinensis root were identified and quantified, and they account for about 91.36% of the total content. The results show that ligustilide, butylene phthalide, 2-methoxy-4-vinylphenol, carvacrol, allo-ocimene,2,6,6-trimethylbicyclo-[3,1,1]hept-2-ene are the main constituents in essential oil of Angelica sinensis root.

Flame retardancy and its mechanism of polymers flame retarded by DBDPE/Sb_2O_3

The flammability characterization and thermal composition of polymers flame retarded by decabromodiphenylethane (DBDPE) and antimony trioxide (Sb2O3) were studied by cone calorimeter and thermogravimetry (TG). The results show that ABS/DBDPE/Sb2O3 has the similar flammability parameters and thermal composition curves to ABS/DBDPO/Sb2O3. It suggests that DBDPE/Sb2O3 has the similar flame retardant behavior to DBDPO/Sb2O3. The heat release rate (HRR) and the effect heat combustion (EHC) curves of polymers flame retarded by DBDPE/Sb2O3 all decrease, but the mass loss rate (MLR) curve slightly increase. It shows that the decrease of HRR is not due to the increase of char formation ratio but the generation of incombustible gases. The major flame retardant mechanism of DBDPE/Sb2O3 is gas phase flame retardant mechanism. Increasing content of Sb2O3 in DBDPE/Sb2O3 can improve the flame retardant property and thermal stability of acrylonitrile butadiene styrene. Sb2O3 has a good synergistic effect with DBDPE.

Identification of Volatile Compounds in Codfish(Gadus) by a Combination of Two Extraction Methods Coupled with GC-MS Analysis

Codfish is a kind of abyssal fish species with a great value in food industry. However, the flavor of codfish, especially the unpleasant odor, has caused serious problems in its processing. To accurately identify the volatile compounds in codfish, a combination of solid phase micro-extraction(SPME) method and simultaneous distillation extraction(SDE) method was used to extract the volatiles. Gas chromatography-mass spectrometry(GC-MS) along with Kovats indices(KI) and authentic standard compounds were used to identify the volatiles. The results showed that a total of 86 volatile compounds were identified in codfish, of them 24 were extracted by SDE, 69 compounds by SPME, and 10 compounds by both SDE and SPME. Seventy volatile compounds were found to have specific odors, of them 7 typical compounds contributed significantly to the flavor of codfish. Alcohols(i.e.,(E)-2-penten-1-ol and 2-octanol), esters(i.e., ethyl butyrate and methyl geranate), aldehydes(i.e., 2-dodecenal and pentadecanal) contributed the most to fresh flavor while nitrogen compounds, sulphur compounds, furans, as well as some ketones(i.e., 2-hydroxy-3-pentanone) brought unpleasant odor, such as fishy and earthy odor. It was indicated that the combination of multiple extraction methods and GC-MS analysis can enhance the accuracy of identification, and provide a reference for the further study on flavor of aquatic products.

CFA与GPMAS在炼油污水氮化合物快速检测中的应用比较

炼油厂污水具有排放源头多、过程监控频次高等特点,因此对其水样分析的方法提出了快速、准确、能批量分析等要求。通过对比研究连续流动分析法(CFA)和气相分子吸收光谱法(GPMAS)两种方法在炼油污水氮化合物分析过程中的标准曲线线性、准确性、重复性以及实际样品测试偏差,明确了这两种方法均适用于炼油污水氮化合物的批量快速分析,但在适用条件、分析效率、系统维护复杂程度、仪器价格等方面存在显著差异,对炼油污水快速批量分析方法的选择具有指导意义。

Diethylstilbestrol in Fish Tissue Determined Through Subcritical Fluid Extraction and with GC-MS

As the key point in sex hormone analysis, sample pre-treatment technology has attracted scientists' attention all over the world, and the development trend of sample preparation forwarded to faster and more efficient technologies. Taking economic and environmental concerns into account, subcritical fluid extraction as a faster and more efficient method has stood out as a sample pre-treatment technology. This new extraction technology can overcome the shortcomings of supercritical fluid and achieve higher extraction efficiency at relatively low pressures and temperatures. In this experiment, a simple, sensitive and efficient method has been developed for the determination of diethylstilbestrol(DES) in fish tissue using subcritical 1,1,1,2-tetrafluoroethane(R134a) extraction in combination with gas chromatography-mass spectrometry(GC-MS). After extraction, freezing-lipid filtration was utilized to remove fatty co-extract. Further purification steps were performed with C_(18) and NH_2 solid phase extraction(SPE). Finally, the analyte was derived by heptafluorobutyric anhydride(HFBA), followed by GC-MS analysis. Response surface methodology(RSM) was employed to optimizing the extraction condition, and the optimized was as follows: extraction pressure, 4.3 MPa; extraction temperature, 26℃; amount of co-solvent volume, 4.7 m L. Under this condition, at a spiked level of 1, 5, 10 μg kg^(-1), the mean recovery of DES was more than 90% with relative standard deviations(RSDs) less than 10%. Finally, the developed method has been successfully used to analyzing the real samples.

Natural Attenuation and Biostimulation of Biodiesel Contaminated Soils from Southern Brazil with Different Particle Sizes

Biodiesel bioremediation in soils may occur by natural attenuation or by engineered techniques, such as biostimulation and bioaugmentation. The present study evaluated the degradation of biodiesel in two soils with different particle size characteristics by the bioremediation processes of natural attenuation and biostimulation. The experiment was carried out ex situ, with the factors temperature, moisture content, and pH being controlled for the experimental period of 110 days. The study aimed at evaluating the biodegradation of a clayey soil （A） and a sandy soil （B）, both contaminated with pure biodiesel, by using the analytical methods of respirometry and gas chromatography. Biostimulation treatments using nitrogen, phosphorus, and potassium solutions （NPK） promoted higher microbiological activity in both soils. At the end of the experiment, it was observed that biostimulation was more efficient when compared to natural attenuation, showing higher biodiesel degradation for both soils A （59.76%） and B （90.41%）.

Principal Component Analysis （PCA） on Multivariate Data of Lard Analysis in Cooking Oil

Discrimination of fatty acids （FAs） of lard in used cooking oil is important in halal determination. The aim of this study was to find the information related to the changes FAs of lard when frying in cooking oil. Quantitative analysis of FAs composition extracted from a series of experiments which involving frying cooking oil spiked with lard at three different parameters; concentration of spiked lard, heating temperatures and period of frying. The samples were analyzed using Gas Chromatography （GC） and Principal Components Analysis （PCA） technique. Multivariate data from chromatograms of FAs were standardized and computed using Unscrambler X10 into covariance matrix and eigenvectors correspond to Principal Components （PCs）. Results have shown that the first and second PCs contribute to the FAs mapping which can be visualized by scores and loading plots to discriminate FAs of lard in used cooking oil

UV enhanced gas–solid synthesis of chlorinated poly vinyl chloride characterized by a UV–Vis online analysis method

Dynamic characteristics of UV enhanced gas–solid PVC chlorination process were revealed by a UV–Vis spectral online analysis method. Experimental results showed an instantaneous increase of the chlorination rate as soon as UV light was affiliated, which demonstrated the intensified effect of UV radiation on PVC chlorination directly.Different affiliation methods of UV light were then studied, proving that continuous UV radiation could enhance the chlorination process significantly while intermittent UV radiation was able to initiate the chlorination reaction once it was conducted. Besides, experiments were carried out to study the influences of parameters on the chlorination process such as UV wavelength, chlorination temperature, partial pressure of chlorine gas and PVC raw materials. Among all the parameters, chlorination temperature and partial pressure of chlorine gas were testified as two key factors to determine the chlorination performance. Thermal analysis of CPVC products showed that their corresponding properties such as the glass transition temperature(Tg) and the homogeneity of chlorine distribution in polymer phase were improved with the increase of chlorine content.

Utilization of Hydrocarbons Obtained by Waste Plastic Pyrolysis： Energetic Utilization （Part Ⅰ）

The pyrolysis of different waste polymers （polyethylene, polypropylene and polystyrene） was investigated in a tube reactor at 550 ℃ in the absence of oxygen. Additionally the energetic utilization of products have also been followed both in refining and petrochemical industry. Pyrolysis products were separated into fractions of gases, naphtha, middle distillates and heavy oil. Raw materials have been collected both from industrial and household sources： polyethylene from agriculture, polyethylene from packaging and polystyrene from packaging and electronic equipments. Yields and properties of volatile products have changed by the raw materials. Products have been analyzed by gas chromatography. Fourier transformed infrared spectroscopy, size exclusion chromatography and other standardized methods. Naphtha had high octane numbers （80 〈 RON）, while high cetane numbers （〉 75） in case of middle distillates. Moreover fractions contained approximately half of unsaturated hydrocarbons, mainly α-olefins, but the percentage was depending on the raw materials. These properties are advantageous for fuel-like applications.

Biodiesel Production by Enzymatic Catalysis Process Using Two Analytical Ways： Gas Chromatography and Total Glycerol Determination

Currently, biodiesel is presented as one of the best alternatives for gradually replacing the use of fossil fuels, but it has some factors that make it economically impractical if it does not have a government support. For this reason, research efforts focused on this area have been responsible for optimizing the process of biodiesel production by different catalytic routes to achieve greater efficiency at a lower cost. In this case, the biggest problem has been the high cost generated by an investigation, which in many occasions is the main factor to decide if an investigation could be carried out. Trying to reduce these costs, in the current study, we are using a technique of glycerol quantification by volumetric methods and comparing obtained results with the chromatographic method, which is conventionally used and comparatively much more expensive. Biodiesel employee was obtained by an enzymatic catalysis process varying one of three process variables：oil：alcohol molar ratio, temperature and proportion of catalyst. The numerical differences obtained between the two quantification methods generated relative errors lower than 10%, resulting in some occasions lower than 1%. By gas chromatography analysis the best yield was obtained at the same conditions of the volumetric method, a temperature of 45 ℃, an oil：alcohol ratio 1：4 and 8 wt.% of catalyst, but a yield of 95.5% and 97.1%, respectively. Due to the high precision of gas chromatography, this method is used to carry out a surface response analysis obtaining as ideal operating conditions a temperature of 43.5 ℃, 8.9 wt.%. of catalyst and an oil：alcohol ratio 1：4.

Analysis Method for Pesticide Residues in Biological Matrices： Gas Chromatography-mass Spectrometry

Pesticides have done a great service to human, but their use is not safe for public health. Apart from pesticides acute toxicity, their chronic toxicity can cause various problems for human health. The objective of this work was to validate a liquid-liquid extraction method, which allows a fairly reliable analysis of pesticides using gas chromatography-spectrometry mass （GC/MS） in toxicology laboratory at National Institute of hygiene, Rabat Morocco. The equipment required to perform these analyzes are the biological matrices （blood, gastric fluid）, in which the authors have doped the Organophosphorus pesticides such as Chlorpyrifos, Dichlorvos and Organochlorine pesticide： dichlorodiphenyltrichloroethane （DDT） and Heptachlor. After extracting the mixture with toluene, the supernatant was collected after centrifugation and concentrated in a small volume of 1.5 mL and then analyzed in GC/MS. After analyzing, the authors found that the yields of each pesticide in samples are significant; respectively they represented 73.4% of Chlorpyrifos, 70.8% of Dichlorvos, 47.8% of DDT and 71.6% of Heptachlor. The blood has a strong link with the most pesticides, where it＇s important to use the GC/MS to identify these products. The extraction with toluene was effective, especially to OP, but it＇s also sensitive to OC.