顶空气相法测定小鼠粪便短链脂肪酸

建立经过简单前处理的顶空气相色谱法(HS-GC)以简便快捷地定量分析小鼠粪便中短链脂肪酸(SCFAs),并测定糖尿病小鼠粪便SCFAs含量。将粪便研磨成粉末,加入内标液后,进行HS-GC分析。结果显示,该方法的前处理简单,可同时测定六种SFCAs,具有良好的专属性、精密度、重复性、稳定性及加样回收率,检测限LODs和定量限LOQs均符合测定要求。该方法可避免复杂前处理的弊端,满足简便快速测定小鼠粪便短链脂肪酸含量的需求。     

气相色谱法测定化妆品中脂肪酸含量

建立了气相色谱法检测化妆品中脂肪酸(十二酸、十四酸、十六酸、十八酸)。采用HP-5毛细管柱,研究脂肪酸甲酯化及气相程序升温的参数,得到了应用保留时间和峰面积对脂肪酸进行定性定量的方法。结果表明,此方法参数可以使化妆品中的脂肪酸得到很好分离,具有较高的准确性和重复性,线性相关系数均为1,测定结果与实际添加量的偏差在2%以内。     

短链脂肪酸测定方法的研究进展

近年来,短链脂肪酸作为肠道菌群的代谢产物已被证实参与宿主的能量代谢,已成为预测肥胖、糖尿病等代谢性疾病及抑郁症,阿尔兹海默等神经精神疾病的生物标志物。因此,如何精准有效的测定短链脂肪酸的水平,对临床疾病的病症进行有效的的预判或诊断已成为科学家研究的重点。本文通过对近几年SCFAs的测定方法(如气相色谱法、液相色谱法、毛细管电泳法、核磁共振法等)等进行综述,为进一步开发高效灵敏的粪便短链脂肪酸测定方法提供依据。     

用气相色谱法测定皂用合成脂肪酸中正构二元酸含量

本文用气相色谱法,以OV-225为固定相成功地分离了皂用合成脂肪酸中正构一元酸(甲酯)与正构二元酸(甲酯),并以C_15,甲基酮为内标求出了C_9~C_16正构二元酸(甲酯)的相对重量校正因子,对皂用合成脂肪酸中正构二元酸进行了定性定量分析,其相对误差<±1.1%,相对标准偏差<±1.2%。     

毛细管气相色谱法测定核桃油中的脂肪酸

讨论了核桃油中脂肪酸的提取方法和毛细管气相色谱法测定条件，并对5种主要脂肪酸进行定量的测定。     

长链脂肪酸淀粉酯合成及应用研究进展

长链脂肪酸淀粉酯是一类具有特殊的热塑性、疏水性、乳化性和可生物降解性的变性淀粉,在食品、纺织、化妆品、医药等行业有着广泛的应用。本文系统地介绍了长链脂肪酸淀粉酯的性质、合成方法和应用领域;分析了各种制备方法的特点,并指出了今后研究方向和发展前景。     

极长侧链脂肪酸生物合成抑制剂及其新品种应用

传统除草剂氯代乙酰胺、氧乙酰胺等是极长侧链脂肪酸生物合成抑制剂,此类除草剂的研究促使发现了除草剂设计中的新靶标—VLCFA延伸酶。Pyraxasulfone是芽前防治玉米与大豆田重要禾本科与阔叶杂草的除草剂,它抑制C18：0至C20：0阶段极长侧链脂肪酸生物合成,用量比氯代乙酰胺类品种低8-10倍。     

洗衣液中脂肪酸盐含量测定

为准确分析洗衣液中脂肪酸盐含量,采用复合脂肪酸洗衣液样品,通过气相色谱法与干钠皂法相结合的分析方法测定其中脂肪酸盐含量,并比较与实际含量的差别.结果表明,测定C12～C18饱和脂肪酸盐及油酸盐的绝对误差均小于0.1％,表观上准确度较高,但对于不同脂肪酸组成洗衣液的测定相对准确度存在一定的差异(相对误差低于5％).该方法...     

固体酸SO_4~(2-)/ZrO_2-SiO_2催化合成长链脂肪酸酯

以固体酸SO_4~(2-)/ZrO_2-SiO_2为催化剂,利用长链脂肪酸(C12~C18)和长链脂肪醇(C12~C18)合成了8个脂肪酸酯,产物结构经IR或1H NMR分析表征。以十二酸十八醇酯为例,采用正交实验法得出了酯化反应的最佳条件为:醇与酸的物质的量比为1∶1.2,反应所用催化剂用量占原料总质量的2.0%,反应时间为2.5h,产率可达85.5%。     

气相色谱法测定食品油脂中的十八碳反式脂肪酸

反式脂肪酸是在油脂的加氢反应或高温精炼过程中伴随产生的一类不饱和脂肪酸,过多的食用这些成分可能会对人体健康产生危害。食品油脂中以十八碳反式脂肪酸最为常见。采用气相色谱法对食品中十八碳反式脂肪酸的检测进行了实验摸索,获得了一套准确度高、精确度好的方法,可应用于日常监督检测。     

油脂中八种脂肪酸的分析测定

油脂经氢氧化钾-甲醇溶液甲酯化后,生成的脂肪酸甲酯用DB-WAX毛细管柱进行分离,GC-FID进行检测。该方法的回收率在91.45%~107.55%,相对标准偏差小于8%,八种脂肪酸的检出限在0.29~1.10μg/mL之间。本方法准确度高,检出限低,能满足实际检测工作的需要。     

气相色谱法测定煤化工废水中酚类和脂肪酸的实验研究

建立了直接测定煤化工废水中酚类和短链脂肪酸的气相色谱分析方法,该法采用强极性毛细管柱,对脂肪酸和酚同时进行分析测定,用外标法进行定量计算。煤气化废水水样中各物质检出限在3 mg/L~10mg/L,标准曲线在考察质量浓度范围(0.01 g/L~10 g/L)内呈线性关系,相关系数在0.999 7以上,相对标准偏差≤7%。该方法无需复杂的前处理,操作简单易行,测定结果准确。     

Structural Determination and Occurrence in Ahiflower Oil of Stearidonic Acid Trans Fatty Acids

Several marine oils and seed oils on the market contain relevant quantities of stearidonic acid (18:4n‐3, SDA). The formation of 18:4n‐3 trans fatty acids (tFA) during the refining of these oils necessitates the development of a method for their quantification. In this study, 18:4n‐3 was isolated from Ahiflower and isomerized to obtain its 16 geometric isomers. The geometric isomers of 18:4n‐3 were isolated by silver ion HPLC (Ag⁺‐HPLC) and characterized by partial reduction with hydrazine followed by gas chromatography analysis. The elution order of all 16 isomers was established using a 100 m × 0.25 mm 100% poly(biscyanopropyl siloxane) capillary column and at the elution temperature of 180 °C. The 4 mono‐trans‐18:4n‐3 isomers produced during the refining of oils rich in 18:4n‐3 were chromatographically resolved from each other, but c6,t9,c12,c15‐18:4 coeluted with the tetra‐cis isomer. These 2 fatty acids (FA) were resolved by reducing the separation temperature to 150 °C, but this change caused tetra‐cis‐18:4n‐3 to coelute with t6,c9,c12,c15–18:4. Combining the results from 2 isothermal separations (180 and 150 °C) was necessary to quantify the 4 mono‐trans 18:4n‐3 FA in Ahiflower oil.     

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.     

气质联机-气相色谱仪测定UASB处理猪废水中挥发性脂肪酸

挥发性脂肪酸（VFA）是厌氧消化过程中主要的中间产物,是判断厌氧降解阶段的主要指标.本实验采用一种新型测定方法,一方面利用气质联机仪定性分析养猪废水中有机物的组分并准确定位各组分的保留时间,与标样在气相色谱仪中挥发性脂肪酸保留时间比较,有效避免了因废水中有机物与挥发性脂肪酸保留时间相近而带来的误差;另一方面气质联机仪测定出废水中的有机物成分,根据其链式结构采用顶空法直接使水样进入气相色谱仪中,减少了水样复杂的前处理过程,缩短了检测时间.     

The Divergent Immunomodulatory Effects of Short Chain Fatty Acids and Medium Chain Fatty Acids

Fatty acids are derived from diet and fermentative processes by the intestinal flora. Two to five carbon chain fatty acids, termed short chain fatty acids (SCFA) are increasingly recognized to play a role in intestinal homeostasis. However, the characteristics of slightly longer 6 to 10 carbon, medium chain fatty acids (MCFA), derived primarily from diet, are less understood. Here, we demonstrated that SCFA and MCFA have divergent immunomodulatory propensities. SCFA down-attenuated host pro-inflammatory IL-1β, IL-6, and TNFα response predominantly through the TLR4 pathway, whereas MCFA augmented inflammation through TLR2. Butyric (C4) and decanoic (C10) acid displayed most potent modulatory effects within the SCFA and MCFA, respectively. Reduction in TRAF3, IRF3 and TRAF6 expression were observed with butyric acid. Decanoic acid induced up-regulation of GPR84 and PPARγ and altered HIF-1α/HIF-2α ratio. These variant immune characteristics of the fatty acids which differ by just several carbon atoms may be attributable to their origins, with SCFA being primarily endogenous and playing a physiological role, and MCFA exogenously from the diet.     

气相色谱法同时检测水中九种卤乙酸和两种除草剂

在美国EPA测定卤乙酸最新标准方法的基础上,加入我国农业生产常用的两种除草剂——茅草枯和2,4．D,对前处理过程和仪器条件进行了的优化,使九种卤乙酸和两种除草剂的检测能同时完成。九种卤乙酸和两种除草剂的检出限均在1．0μg／L以下,加标回收率在90．0％-110．0％之间。     

Fatty Acids and Flavor Components in the Oil Extracted from Golden Melon Seeds

For complete utilization of raw materials and edible oil production, the oil from golden melon seeds (GSs) is extracted via the cold-pressing, hot-pressing, and ultrasound-assisted aqueous enzymatic extraction (AEE), and the fatty acid composition, and nutritional value of the extracted GS oils (GSOs) are analyzed. The volatile compounds present in the GSOs are determined using gas chromatography–mass spectrometry. The aroma profiles of different GSO samples are further distinguished by using an electronic nose. A total of 16 fatty acids are identified in the GSO samples, with atherogenic, thrombogenic, and nutritive value indices ranging from 0.142–0.151, 0.366–0.403, and 5.019–5.299, respectively. Moreover, 43 volatile compounds, including esters, hydrocarbons, alcohols, ketones, pyrazines, and aldehydes are identified. The cold-pressed GSO presents fresh and fruity flavors, while the hot-pressed GSO presents roasted, nutty, fatty, and fruity flavors, and the GSO obtained via AEE presents fatty and fruity flavors. The acid and peroxide contents of these oil samples are 0.69–079 mg g⁻¹ and 5.17–5.79 mmol kg⁻¹, respectively. The results indicate that the extraction method affects the fatty acid composition, flavor components, and physiochemical properties of the GSO. This study may help promote the development of edible GSO. Practical applications: With high demand for edible oils, it is of great significance to find natural edible oils from different sources. The oil in golden melon seeds is extracted by different methods. Their fatty acid composition and flavor components are analyzed. The GSO extracted via AEE method is rich in fatty acids composition. This work would guide the development of an edible GSO and increase the value of golden melon.     

越南安息香种子脂肪酸的在线甲基化-GC分析研究

建立了分析越南安息香种子油、果实和果壳的脂肪酸组成的在线甲基化-气相色谱法。将微克级的安息香样品与2μL衍生化试剂三甲基氢氧化硫（0.2 mol/L）加入裂解器,在350℃下瞬间反应,由气相色谱在线检测到8种脂肪酸甲酯成分,主要有棕榈酸（ C16∶0）、硬脂酸（ C18∶0）、油酸（ C18∶1）、亚油酸（ C18∶2）和亚麻酸（ C18∶3）,不饱和脂肪酸含量在84.5%以上,其中亚油酸含量最高,达47.29%。5次平行测定的相对标准偏差（ RSD）小于3.81%。并结合相似性分析法比较了4种不同产地的安息香种仁与6种食用油的脂肪酸组成,相似性结果表明不同产地的安息香种仁的脂肪酸组成相似,其脂肪酸组成与食用植物油相近,与玉米油的组成分布最为接近,相似系数在0.987~0.990,且越南安息香种子中人体必需的多不饱和脂肪酸含量（ C18∶2和C18∶3）与大豆油和葵花籽油相近,高于一般植物油,具有较高的营养价值。结果表明该法简便、快速、准确,适合越南安息香种子油脂的测定。