Simultaneous Determination of Free Fatty Acids and Esterified Fatty Acids in Rice Oil by Gas Chromatography

Free fatty acids (FFA) in crude rice oil were selectively and stoichiometrically derivatized to fatty acid N,N-dimethylamides (FADMA) by catalytic condensation at 45 °C, and then esterified fatty acids (eFA) were directly converted to fatty acid methyl esters (FAME) at 37 °C. The mixture of FADMA and FAME formed in a single test tube was injected into the capillary column of a gas chromatograph (GC). No mutual contamination occurred between FFA and eFA, and reliability of the method was confirmed by comparison between GC data obtained by this method and by a conventional isolation method. The advantages of the present method are that no FFA isolation procedures are required, the reactions proceed under mild temperature conditions, and FFA and eFA can be analyzed simultaneously by GC.     

Metabolic Conversion of C20 Polymethylene-Interrupted Polyunsaturated Fatty Acids to Essential Fatty Acids

Polymethylene-interrupted (PMI)-polyunsaturated fatty acids (PUFA) are fatty acids present largely in gymnosperm. Sciadonic acid (SciA, 20:3 Δ-5,11,14) and juniperonic acid (JA, 20:4 Δ-5,11,14,17) are typical C20 PMI-PUFA with an isolated double bond at Δ5. Previously, we found that SciA and JA are converted to linoleic acid (LNA) and α-linolenic acid (ΑLA), respectively. The conversion process includes chain-shortening step by peroxisomal β-oxidation for elimination a double bond at Δ5, and subsequent chain-elongation step in microsomes. In this study, we examined the substrate specificity of this metabolism in rodent and human cells. Supplementation of SciA, eicosadienoic acid (EDA, 20:2 Δ-11,14) or JA to CHO-K1 cells (wild type) induced an accumulation of LNA, LNA or ALA, respectively, in cellular lipids. These changes were not observed in the peroxisomes-deficient CHO cells, indicating involvement of peroxisomes in the metabolism. Two types of human cells (MKN74 and HepG2) also converted the C20 PMI-PUFA and EDA to the respective essential fatty acids. In contrast, no chain-shortened metabolite of pinolenic acid (18:3 Δ-5,9,12) was detected in any cell lines tested. From these results, C20 PMI-PUFA and EDA, but not C18 PMI-PUFA, are suggested as being effectively converted to essential fatty acids by the fatty acid remodeling system in rodent and human cells.     

胆汁酸溶解度的测定与数据关联

在胆汁酸结晶过程中,温度对胆汁酸在不同有机溶剂中溶解度的影响至关重要。采用平衡法结合HPLC法测定303.15~353.15 K胆酸、鹅去氧胆酸、熊去氧胆酸在5种有机溶剂中的溶解度,分别采用多项式经验方程和理想溶液方程对实验数据进行关联。结果表明,胆酸、鹅去氧胆酸、熊去氧胆酸在不同有机溶剂中的溶解度均随温度升高而增加,这两种方程均能较好地关联溶解度实验数据,其中多项式经验方程关联的相关系数均在0.98以上。     

混合脂肪酸的分离

以一般油脂加工副产物十八碳混合脂肪酸为原料,采用配合结晶梯度冷冻反萃取分离技术,不经任何热处理以避免聚合作用的发生,使混合脂肪酸中的饱和脂肪酸与不饱和脂肪酸分离,同时将不饱和脂肪酸分成油酸和(亚油酸+亚麻酸)两组分。后者含量可达95%以上。     

石油馏分中的环烷酸分离

对于各种石油馏分中酸及油的分离方法进行了评价。传统的碱液脱酸工艺仍具有良好的发展前曩，醇胺脱酸技术，分离效果好，且环境污染少，但能耗高，脱酸油色度受影响。其它方法尚在实验阶段。     

超声条件下单取代芳基硼酸的合成研究

在超声条件下,以碘为催化剂,利用硼酸酯与卤代芳烃、金属镁粉合成了4种单取代芳基硼酸.确定了反应的最佳工艺条件:在碘的催化作用下,超声波功率170 W,反应温度46℃,反应时间30min,产物收率79%～86%.研究表明,随着硼酸酯取代基空间结构的增大,收率也会提高.产品经1HNMR、IR进行了确认.     

环烷酸的分离提纯方法

本文简要介绍了环烷酸的来源，分子结构和提纯方法。环烷酸的提纯方法主要有物理方法和化学方法。物理方法包括蒸馏法，吸附法等。化学方法包括酸洗法，皂化法，酰化法和酯化法等。     

固体酸催化酯化反应的研究进展

对目前研究较多的 3类新型催化酯化固体酸催化剂 :固体超强酸、分子筛和杂多酸进行了概述。以SO2 -4/MxOy 型金属氧化物固体超强酸为例 ,介绍了其负载物的结构特点、催化机理及其在酯化反应中的应用 ;按分子筛的发展历程分别简介了沸石类分子筛、中孔分子筛和复合型分子筛 ;并对杂多酸及其化合物的结构组成和催化特点进行了简要评述。最后通过固体酸催化剂目前存在的问题 ,展望了其今后的研究方向和重点。     

对腐植酸类标准中一些概念的质疑与建议

腐植酸标准化工作中存在许多亟待商榷和统一的概念和定义。本文就腐植酸、黄腐酸、有机质、碳系数等的定义和分析方法，以及数据表达基准、计算公式、标准制定和基础研究等方面的问题提出个人的看法与建议。     

硫铝酸盐水泥抗酸侵蚀性能与机理研究

本文研究了硫铝酸盐水泥(CSA)在盐酸和硫酸环境下的力学性能演化规律,并探究了其抗酸侵蚀机理。分别测试了水和酸溶液养护的CSA胶砂试件的抗折强度,计算了CSA的抗酸侵蚀系数。采用XRD、TGA、CT和SEM分析了酸侵蚀导致的产物种类和数量变化,表征了微观结构演化过程。结果表明:与普通硅酸盐水泥(OPC)相比,CSA在盐酸和硫酸中抗折强度损失率更低,具有更好的抗盐酸和硫酸侵蚀能力;CSA主要水化产物(钙矾石)比OPC主要水化产物(氢氧化钙和硅酸钙凝胶)更难与酸反应,因此抗酸侵蚀能力更强。盐酸与硫酸对CSA的侵蚀机制略有不同,盐酸对CSA的侵蚀过程实质上为氢离子对CSA水化产物钙矾石的酸解,硫酸对CSA的侵蚀则是氢离子和硫酸根离子的共同作用。     

杂多酸的催化、阻聚作用

探讨了杂多酸的结构特征与催化性能之间关系 ,对杂多酸的酸催化和氧化 -还原催化 ,特别是对烯类单体的阻聚作用的最新研究成果进行了综述。     

3-芳基丙烯酸及其酯的合成

研究了以无水碳酸钾作催化剂 ,芳香醛与酸酐反应合成 3 芳基丙烯酸 ,用对甲苯磺酸催化酯化反应合成 3 芳基丙烯酸酯。产品结构经1HNMR、IR和元素分析证明与预期结构相符。     

食品接触材料中羟酸迁移量的研究

采用高效液相色谱内标法同时检测食品接触材料中对苯二甲酸、间苯二甲酸、顺丁烯二酸3种羟酸的迁移量。从流动相、流动相梯度、紫外波长3个方面对色谱条件进行了优化,并计算了方法的检出限、定量限、回收率和相对标准偏差,最后,按照优化后的色谱条件测试了样品中对苯二甲酸、间苯二甲酸、顺丁烯二酸的迁移量。结果表明,在1~20 mg/L范围内线性良好,相关系数R>0.999,回收率为98.3 %~109.7 %,相对标准偏差为0.14 %~3.75 %,方法准确度、精密度高;11 min内完成一次检测,分析效率高,是一种简单、经济的方法;在正常使用条件下,样品中对苯二甲酸、间苯二甲酸、顺丁烯二酸的迁移量符合限量要求,证实了食品接触材料的安全性,而误用条件下的安全评价需进一步试验。     

Hepatocyte Proteome Alterations Induced by Individual and Combinations of Common Free Fatty Acids

Non-alcoholic fatty liver disease is a pathology with a hard-to-detect onset and is estimated to be present in a quarter of the adult human population. To improve our understanding of the development of non-alcoholic fatty liver disease, we treated a human hepatoma cell line model, HepG2, with increasing concentrations of common fatty acids, namely myristic, palmitic and oleic acid. To reproduce more physiologically representative conditions, we also included combinations of these fatty acids and monitored the cellular response with an in-depth proteomics approach and imaging techniques. The two saturated fatty acids initially presented a similar phenotype of a dose-dependent decrease in growth rates and impaired lipid droplet formation. Detailed analysis revealed that the drop in the growth rates was due to delayed cell-cycle progression following myristic acid treatment, whereas palmitic acid led to cellular apoptosis. In contrast, oleic acid, as well as saturated fatty acid mixtures with oleic acid, led to a dose-dependent increase in lipid droplet volume without adverse impacts on cell growth. Comparing the effects of harmful single-fatty-acid treatments and the well-tolerated fatty acid mixes on the cellular proteome, we were able to differentiate between fatty-acid-specific cellular responses and likely common lipotoxic denominators.     

n-3 Polyunsaturated Fatty Acids and Atopy in Korean Preschoolers

Atopy is a growing problem for Korean children. Since eicosapentaenoic acid is a precursor of less active inflammatory eicosanoids, n-3 polyunsaturated fatty acids (PUFA) may have a protective effect on atopy. This study was undertaken to determine whether n-3 PUFA in red blood cells (RBC) is lower in atopic than in non-atopic preschoolers. Three hundred and eight Korean children aged 4–6 years were enrolled. Total RBC fatty acid composition was measured by gas chromatography. The prevalence of atopic dermatitis, allergic rhinitis, or asthma was 29%. Total RBC n-3 PUFA were lower in preschoolers with atopy than controls (9.8 ± 1.2 vs. 11.4 ± 1.6%; P < 0.05), while n-6 PUFA (33.0 ± 1.4 vs. 32.2 ± 1.0%; P < 0.05) and n-6/n-3 PUFA ratio (3.4 ± 0.6 vs. 2.8 ± 0.5; P < 0.05) were greater. The following factors were also associated with an increase in atopy: higher saturated fatty acids (39.6 ± 1.4 vs. 40.6 ± 1.9; P < 0.05) and arachidonic acid (15.3 ± 1.6 vs. 16.0 ± 2.9; P < 0.05), and lower total PUFA (43.8 ± 0.7 vs. 42.8 ± 1.4; P < 0.05) and omega-3 index (EPA + DHA; 9.1 ± 0.8 vs. 7.8 ± 0.5; P < 0.05) in RBC. Maternal history of atopy was a significant (P < 0.05) risk factor, while lactation was not. The results suggest that a reduced content of n-3 PUFA in the RBC membrane could play a role in early children atopy.     

三辛胺萃取丁二酸、苹果酸、马来酸、富马酸特性的研究

Extraction equilibrium features of succinic acid, malic acid, maleic acid and fumaric acid were investigated systematically with trioctylamine (TOA) in chloroform, 4-methyl-2-pentanone (MIBK) and 1-octanol. Fourier transform-infrared (FTIR) spectroscopic analysis of organic samples loaded with the acid shows that amine forms 1:1 complex of ion-pair association with succinic acid, malic acid and maleic acid, and 1:1, 2:1 complex of ion-pair association with fumaric acid. It is proposed that the complex forms depend on the second dissociation constant of the dibasic acid, pKa2 Results of equilibrium experiments show that diluents affect extraction behavior, and depend on the solute concentration. Protic diluents, chloroform and 1-octanol, are more effective than the others when the equilibrium solute concentration is lower than 1:1 stoichiometry of TOA to acid, otherwise the extraction ability shows that MIBK>l-octanol>chloroform for malic and maleic acids, and l-octanol>MIBK>chloroform for succinic acid.     

在教学实验中用固体酸催化酯化反应

酯化反应是常见的有机反应,通常是在酸催化作用下由羧酸与醇反应生成酯。采用固体酸代替硫酸应用在酯化反应的实验中,几种固体酸对酯化反应的催化活性好,反应时间短,转化率高。避免了使用硫酸时的安全问题,在大学教学实验中,收到了良好的教学效果。     

Identification of Aromatic Fatty Acids in Butter Fat

Bovine milk fat contains a large variety of structurally different fatty acids. In this study, we describe the presence of aromatic fatty acids in a butter fat sample. Fatty acids were released from butter fat and converted into the corresponding methyl esters (FAME). Urea complexation was used to separate the main saturated fatty acids. GC/MS screening of the FAME in the filtrate of the urea complexation indicated the presence of aromatic fatty acids. By (1) conversion of two representatives into picolinyl esters which were analyzed by GC/MS, (2) linear log t_R over carbon number plots (R² = 0.95) and by the use of two reference standards we were able to show that the phenyl unit was located on the terminal carbon of the straight acyl chain of the FAME. In a fraction gathered by countercurrent chromatography we were able to identify 3‐phenylpropionic acid (Ph‐3:0), 4‐phenylbutyric acid (Ph‐4:0), 5‐phenylpentanoic acid (Ph‐5:0), 6‐phenylhexanoic acid (Ph‐6:0), 7‐phenylheptanoic acid (Ph‐7:0), 8‐phenyloctanoic acid (Ph‐8:0), 9‐phenylnonanoic acid (Ph‐9:0), 10‐phenyldecanoic acid (Ph‐10:0), 11‐phenylundecanoic acid (Ph‐11:0), 12‐phenyldodecanoic acid (Ph‐12:0), 13‐phenyltridecanoic acid (Ph‐13:0), along with one unsaturated phenyldecenoic acid (Ph‐10:1) isomer. Preliminary results indicate that the aromatic fatty acids may have been formed exogenously in the rumen of the cows. The total amount of the aromatic fatty acids was estimated at 0.15 mg/g butter fat, which corresponds with an average daily intake of ~5 mg per day in Germany and ~4.4 mg per day in Europe.     

络合萃取法分离一元有机羧酸盐析效应的研究

络合萃取法对极性有机物稀溶液的分离具有高效性和高选择性,今选择醋酸、丁酸为分离对象,三烷基胺为络合剂,正辛醇为极性稀释剂,加氢煤油和甲苯为惰性稀释剂,考察了无机盐硫酸钠、氯化钠、硝酸钠对萃取过程的影响,探讨了分配系数 D 随盐浓度变化的规律,分析了产生盐析效应的原因,并对实验数据进行关联得到盐析效应的经验公式.     

含钾硅酸盐肥料在盐酸与柠檬酸中的溶解行为

为研究高温煅烧法制备的含钾硅酸盐肥料在酸性条件下的溶解行为,选择盐酸与柠檬酸作为浸提液,在室温下研究营养元素溶出与矿物组成的变化,探讨硅酸盐肥料包含矿物遇酸发生的化学反应.结果表明:浸提液pH值越低,元素溶出越多;pH值为2.1的柠檬酸的溶解作用强于pH值为2.1的盐酸.pH值为0.3的盐酸对硅酸盐肥料矿物的溶解率最高...