Analysis of antioxidants in oil

Oils containing from 0 to 200 ppm of the most common phenolic antioxidants, BHA, BHT and TBHQ, were analyzed by a new gas chromatographic method. This method requires neither extraction of antioxidants from oil nor derivatization of antioxidants. The correlation coefficients (r) between gas chromatographic peak heights or peak area and their concentrations in oils were 0.99 for BHA, BHT and TBHQ. This simple gas chromatographic method can accurately determine as little as 10 ppm of BHA, BHT and TBHQ in oils in 1 hr.     

一种新型气相色谱固定液的制备及应用

以柠檬酸、OP-10和二乙醇胺为原料合成了柠檬酸壬基酚聚氧乙烯醚单酯二乙醇酰胺。用红外光谱法表征了结构,热分析技术考察了热稳定性。以此产物作为气相色谱固定液,对一些混和组分进行分离,效果良好。     

Sulphonated Biphenylated Poly(aryl ether ketone)s for Fuel Cell Applications

New series of fully aromatic poly(ether ketone)s with a biphenyl pendant groups were synthesised. A direct comparison of sulphonation reaction among monophenylated poly(ether ether ketone) (Ph‐PEEK), biphenylated poly(ether ether ketone) (BiPh‐PEEK) and PEEK (Victrex) was thoroughly investigated. Several advantages of the pendant‐phenyl poly(ether ketone)s compared with commercial PEEK were identified, including ready control over the site of sulphonation and degree of sulphonation (DS), and mild and rapid sulphonation. The basic membrane physical properties comprising of thermal and mechanical properties, dimensional stability and proton conductivity were studied. One new membrane, sulphonated biphenylated poly(ether ether ketone) (BiPh‐SPEEKDK) having a good combination of membrane properties was fabricated into a membrane electrode assembly (MEA), and it showed excellent direct methanol fuel cell (DMFC) performance.     

Kinetics of isothermal and nonisothermal crystallization of novel poly(arylene ether ether sulfide)s

The kinetics of crystallization have been studied for a series of novel poly(ether ether sulfide)s based on a biphenyl moiety in the backbone (M_n = 14.3K, 19.1K), referred to as biphenyl sulfide (T_g = 142°C, T_m = 347°C) and phenyl moieties in the backbone (M_n = 8.1K, 19.9K, 34K), referred to as phenyl sulfide (T_g = 100°C, T_m = 243°C). Isothermal melt crystallization kinetics were analyzed based on the Avrami equation. Avrami exponents close to three were obtained for the phenyl sulfides, independent of molecular weight or crystallization temperature, which implies growth of three-dimensional spherulitic superstructures following heterogeneous nucleation. For the biphenyl sulfides, values closer to 2 were obtained for the exponent, also independent of molecular weight or crystallization temperature, which could imply the incomplete development of three-dimensional superstructures following heterogeneous nucleation. Nonisothermal crystallization kinetics were also studied by cooling from the melt; in all cases studied, the Ozawa analysis could not well describe the evolution of crystallinity, probably because of the inapplicability of some of the inherent assumptions in this type of analysis. The data were analyzed using the conventional form of the Avrami equation, which yielded good fits. This semiquantitative method of analysis yields a reduced rate constant that was found to increase with increasing cooling rate and decreasing molecular weight. The results of the isothermal and nonisothermal crystallization studies carried out on the poly(ether ether sulfide)s have been compared wherever possible to the results available for PPS and PEEK.     

液化石油气中二甲醚的气相色谱分析

建立了利用填充柱测定液化石油气中二甲醚含量的气相色谱方法。采用水浴完全气化样品,气体进样六通阀进样,热导池检测器检测。定量标准曲线的相关系数大于0.999,最低检测限(S/N=3)为0.8%(V/V),该方法简便快速,已成功地应用于液化石油气样品的测定。     

气相色谱法检测液化石油气中各组分和二甲醚含量分析

本文采用二甲醚专用分析柱对二甲醚和液化石油气组分含量进行气相色谱法分析。实验表明,该方法对二甲醚、C2、C3、C4以及C5各组分都有良好的分离效果,测定结果回收率在98.46%~102.36%,有较好的准确度和精密度;同时能够满足标准《SH/T 0230-1992》对色谱柱的分离要求和实验结果的精密度要求。     

CO_2加氢合成二甲醚反应产物的快速分析

采用GDX-101和GDX-401耦合双柱,可有效、快速、方便地分析出CO2加氢合成二甲醚反应产物气中CO、CO2、水、甲醇、二甲醚等。考察了柱温、载气流速等对保留时间和分离度的影响,测定了相对物质的量校正因子,并应用于CO2加氢合成二甲醚催化剂评选,得到了满意的结果。     

1-丁烯中微量甲基叔丁基醚和甲醇含量的测定方法改进

根据测定1-丁烯中微量甲基叔丁基醚和甲醇的分析方法中存在的问题,分别对进样方式、毛细管色谱柱和仪器操作条件作了改进,建立了一次进样便可同时检测甲基叔丁基醚和甲醇的气相色谱法。改进后的方法操作简便,分离效果及重复性良好。     

Design and synthesis of aryl ether inhibitors of the Bacillus anthracis enoyl-ACP reductase

The problem of increasing bacterial resistance to the current generation of antibiotics is well documented. Known resistant pathogens such as methicillin-resistant Staphylococcus aureus are becoming more prevalent, while the potential exists for developing drug-resistant pathogens for use as bioweapons, such as Bacillus anthracis. The biphenyl ether antibacterial agent, triclosan, exhibits broad-spectrum activity by targeting the fatty acid biosynthetic pathway through inhibition of enoyl-acyl carrier protein reductase (ENR) and provides a potential scaffold for the development of new, broad-spectrum antibiotics. We used a structure-based approach to develop novel aryl ether analogues of triclosan that target ENR, the product of the fabI gene, from B. anthracis (BaENR). Structure-based design methods were used for the expansion of the compound series including X-ray crystal structure determination, molecular docking, and QSAR methods. Structural modifications were made to both phenyl rings of the 2-phenoxyphenyl core. A number of compounds exhibited improved potency against BaENR and increased efficacy against both the Sterne strain of B. anthracis and the methicillin-resistant strain of S. aureus. X-ray crystal structures of BaENR in complex with triclosan and two other compounds help explain the improved efficacy of the new compounds and suggest future rounds of optimization that might be used to improve their potency.     

超声波萃取-高效液相色谱测定电子产品中多溴二苯醚

文章采用超声波萃取-高效液相色谱建立了测定电子电器产品中的方法：选用正丙醇作为萃取剂,采用超声波萃取装置对电子电器产品中的溴系阻燃剂,以甲醇/超纯水为流动相,在反相C18色谱柱上进行梯度淋洗,检测波长226 nm,该方法对于9种目标多溴二苯醚的回收率为92%~96%,相对标准偏（RSD）均小于5%,该方法的检测限为〈0.1 mg/kg,具有良好的准确性和精密度。可以满足RoHS指令中溴阻燃剂的测定分析。如用该方法对普通电路板进行测定,可知道其中PBDE-209的含量约为314.7436 mg/kg。     

Effects of variation in composition and temperature on the amine cure of an epoxy resin model system

Prior liquid chromatographic studies have shown that the reactions in epoxy resin model system phenyl glycidyl ether, p-chloroaniline, and Monuron include amine addition to epoxy, homopolymerization of the epoxy, and a chain-transfer reaction involving the hydroxy groups of the addition products. The present work examines the effect of variation in concentration of the accelerator Monuron, the amine-to-epoxy ratio, and the temperature on the competitive reaction mechanisms. The fraction of phenyl glycidyl ether reacting by homopolymerization increases with accelerator concentration and decreases with increasing amine-to-epoxy ratio and increasing temperature. The estimated contribution from chain transfer is much smaller and appears to parallel the homopolymerization reaction, as might be expected.     

Determination of 6-ketocholestanol in unirradiated and irradiated chicken meats

A method to detect 6-ketocholestanol in unirradiated and irradiated chicken meats was developed by means of chloroform-methanol-water extraction, adsorption chromatographic column separation and gas chromatography. This method is able to measure cholesterol oxidation products at levels that are much lower than those of previous methods. The new procedure was used to detect 6-ketocholestanol in fresh, unirradiated chicken and measured more than 97% of the test compound added to chicken below the ppm level. Irradiation of the chicken meats to a dose of 10 kGy increased the concentration of this compound to about four times the level of unirradiated meats.     

Simultaneous analysis of BHA,TBHQ, BHT and propyl gallate by gas chromatography as extracted from refined vegetable oil

A method has been developed for the simultaneous gas chromatographic (GC) analysis of 4 phenolic antioxidants extracted from refined cottonseed oil. The antioxidants in the study were butylated hydroxyanisole (BHA), tertiary butyl hydroquinone (TBHQ), butylated hydroxytoluene (BHT), and propyl gallate (PG). The method involves extraction with acetonitrile, followed by silyl derivatization prior to GC injection. The method was applied to a study designed to measure the percentage of recovery of each antioxidant at the 100 ppm level over a two-week time span. Statistical treatment of the results indicate there is no significant time trend in any of the 4 antioxidants. The percentage recoveries range from 84% to 108%. The standard deviations for the analysis range from 8 ppm to 10.2 ppm.     

Poly(ethyene terephthalate)–solvent interaction: Gelation and melting point depression

The interactions between poly(ethylene terephthalate) (PET) and six high temperature solvents are discussed in terms of gelation and melting temperature depression. The six solvents are 1′-acetonaphthone (AN), phenyl ether (PE), biphenyl (BP), 1-methyl naphthalene (MN), nitrobenzene (NB), and a eutectic mixture of phenyl ether and biphenyl (EU). Although the six solvents have very similar solubility parameter values, the dissolution, gelation, and gel melting temperatures of the PET-solvent systems are vastly different. The characteristic transition temperatures (dissolution, gelation, and gel melting temperatures) of the six solvents decrease in the following order: PE > EU > BP > MN > AN > NB, which is the reverse order of the solvent power. While the transition temperatures of the gel vary with the solvent system, the melting temperature of the dry gel formed from quiescent solution is independent of solvent system. That is, PET-solvent interactions are only discernible in solvated state (wet gel). All the experimental results suggest crystallization is the primary cause of gelation of high temperature PET solutions, with crystals acting as junction points in the network. Based on the dissolution and gel melting temperatures, interaction parameters for the six PET-solvent systems have been calculated.     

A study of odor stability of commercial stearic acid through isolation and identification of its volatile odoriferous compounds

Commercial stearic acid may have an iodine value of less than 0.5. However, it develops a characteristic objectionable odor quite rapidly, sometimes before a shipment has reached its destination. The present investigation is an identification of the volatile odoriferous compounds which are responsible for this undesirable odor. Volatile compounds were isolated from commercial stearic acid and separated into acidic and nonacidic compounds. The acidic fraction did not have the characteristic off-odor of the commercial stearic acid and was discarded. The nonacidic fraction was fractionated into pure compounds by repeated gas chromatography, which then were identified by a combination of gas chromatographic retention time and IR and mass spectrometry. A total of 52 compounds was identified positively. They contained a relatively large number of lactones, viz, 7 γ-lactones, 4 δ-lactones, and 2 γ-2-ene lactones. The other identified compounds were 11 saturated hydrocarbons, 7 saturated primary alcohols, 6 saturated methyl ketones, 10 saturated normal aldehydes, 4 saturated esters, and 1 diphenyl ether. In addition, 2 saturated aldehydes and 1 γ-3-ene lactone were identified tentatively. The odors of the saturated and unsaturated lactones were reminiscent of the objectionable odor characteristic of commercial stearic acid. Quantitative estimation indicated that commercial stearic acid contained: 0.47 ppm of 4-hydroxy-hexanoic acid, lactone; 0.06 ppm of 4-hydroxy-heptanoic acid, lactone; 0.31 ppm of 4-hydroxy-octanoic acid, lactone; 0.06 ppm of 4-hydroxy-nonanoic acid, lactone; and 0.53 ppm of 4-hydroxy-undecanoic acid, lactone. Paper of the Journal Series, New Jersey Agricultural Experiment Station, Cook College, Rutgers, The State University of New Jersey, Department of Food Science, New Brunswick, N.J. 08903.     

Phosphorus‐containing polyhedral oligomeric silsesquioxane/polyimides hybrid materials with low dielectric constant and low coefficients of thermal expansion

Novel phosphorus‐containing polyhedral oligomeric silsesquioxane (POSS)/polyimides (PI) hybrid materials with low dielectric constant and low linear coefficients of thermal expansion (CTE) were prepared and characterized. The POSS/PI hybrid materials were synthesized with octa(aminopropyl)silsesquioxane (OAPS) and a series of phosphorus‐containing polyamide acids(PAA). The PAAs were synthesized with bis(4‐aminophenoxy) phenyl phosphine oxide (BAPPO), 4,4’‐diaminodiphenyl ether (ODA) and 3,3',4,4'‐biphenyl tetracarboxylic diandhydride (BPDA). The structures and properties of the hybrid materials were characterized. And the effect of the phosphorus‐containing structure on the POSS/PI hybrid materials was discussed. The dielectric constants and CTE of the hybrid materials were remarkably lower than that of the unmodified POSS/PI films. The lowest values of dielectric constant and CTE could achieve as low as 2.64 (1 MHz) and 27.45 ppm/K. Besides, the hybrid materials also had excellent thermal properties. The highest 5% weight loss temperature of the hybrid materials was as high as 580°C under air. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42611.     

Effects of β-carotene on light stability of soybean oil

β-Carotene was added to soybean salad oils to study its effect in inhibiting flavor deterioration due to light exposure. Flavor evaluations indicated that (a) when oils treated with citric acid were exposed to light (7535 lux) for 8 to 16 hr, oils containing 5 to 10 ppm β-carotene showed improved flavor stability compared to oils containing 0 to 1 ppm β-carotene; and (b) when oils were not treated with citric acid, only oils containing 20 ppm β-carotene were more stable to light. Capillary gas chromatographic analysis showed that the addition of 1 to 20 ppm of β-carotene significantly decreased formation of 2-heptenal and 2,4-decadienal in the absence or presence of citric acid. Determination of peroxide values showed the same trends as gas chromatographic analyses of volatiles. In the presence of 15 and 20 ppm β-carotene, some off-flavors, as well as poor ratings for color quality, were reported by panelists. Therefore, flavor deterioration initiated by light can be inhibited effectively in soybean oil, without affecting color quality, by addition of β-carotene at concentrations from 5 to 10 ppm to oils treated with citric acid.     

Bis[4(1-methyl-1,2-epoxyethyl)] derivatives of phenyl ether, 1,4-diphenoxybenzene,and bis(4-phenoxyphenyl) ether

The syntheses of three new α-methyl-substituted bis(epoxyethyl) derivatives of phenyl ether, 1,4-diphenoxybenzene, and bis(4-phenoxyphenyl) ether are reported. Improved procedures for preparing 1,4-diphenoxybenzene and bis(4-phenoxyphenyl) ether by the Ullmann method are described. Infrared spectral data for the bisepoxides and their precursors are given, as are some reactions of the bisepoxides.     

含芳醚配体的芳茂铁盐的合成研究

以Lewis酸AlCl3为催化剂,分别考察了二茂铁与苯甲醚、二苯醚、苯基正丁基醚、苯基正辛基醚和苯基正十六烷基醚的配体交换反应.发现二茂铁与苯甲醚和二苯醚反应可以合成出带有醚键的芳茂铁盐,即(环戊二烯基-铁-苯甲醚)盐和(环戊二烯基-铁-二苯醚)盐,而二茂铁与苯基正丁基醚、苯基正辛基醚和苯基正十六烷基醚的反应产物均为(环戊二烯基-铁-苯酚)盐.通过FT-IR和 1HNMR对上述产物进行了结构表征,并提出了可能的反应机理.     

顶空气相色谱法测定醇醚硫酸盐中1,4-二噁烷的含量

本文介绍了顶空气相色谱法测定醇醚硫酸中1,4-二烷含量的测试方法。对顶空气相色谱法的主要条件、油浴温度、平衡时间、液上压力及气液体积比进行了讨论,确立了最佳测试条件。采用顶空法测定醇醚硫酸盐中的1,4-二烷可得平均回收率为98％,方法的精密度为3．2％。此方法适用于中控和成品分析。