酸性离子液体催化油酸酯化合成生物柴油简

酸性离子液体具有催化活性好、选择性高及易于回收等优点,是一种应用前景非常好的环境友好的酸性催化剂,在生物柴油合成反应中具有重大的理论意义和应用价值. 本文以油酸和甲醇为原料,探讨了7种不同酸性离子液体在生物柴油合成反应中的催化效应. 研究表明,离子液体酸性越强,催化酯化活性越高;引入磺酸基团可大大增强离子液体Brönsted酸性,使其在酯化反应中发挥溶剂/催化剂的双重作用,促进酯化反应向产物方向进行,达到高产率,因而1-丁基磺酸-3-甲基咪唑硫酸氢盐（[BHSO₃MIM]HSO₄）催化效果最好. 此外,系统研究了[BHSO₃MIM]HSO₄催化油酸与甲醇酯化反应,并采用响应面法优化了反应条件. 结果发现,该反应的最适醇酸摩尔比、催化剂用量、反应温度及反应时间分别为4：1,10%（基于油酸的质量）,130 ℃和4 h;在此条件下,生物柴油产率为97.7%. [BHSO₃MIM]HSO₄连续使用10批次后,仍能保持初始催化活性的95.6%,表现出极好的操作稳定性. 另外,利用该离子液体催化游离脂肪酸含量为72%的废油脂生产生物柴油,反应6 h可获得产率94.9%. 可见,[BHSO₃MIM]HSO₄在酯化生产生物柴油方面具有巨大的应用潜力.     

生物柴油树种油脂脂肪酸组成对燃料特性的影响

以目前中国主要开发或具有开发潜能的10种生物柴油树种为研究对象,分析其果实或种子油脂脂肪酸组成对合成生物柴油燃料特性的影响。结果表明,木本植物生物柴油产品十六烷值、碘值、氧化安定性等燃料特性主要由原料油脂肪酸的不饱和度决定,脂肪酸不饱和度低于133.13,十六烷值(GB/T 20828-2007)和碘值(EN 14214)就可以达标。生物柴油产品冷滤点随着长碳链饱和脂肪酸的增加而升高,脂肪酸饱和碳链长度因子分别小于8.41和2.72时,可以满足冷滤点0℃和-10℃的要求。高品质生物柴油的原料中应该具有较高的单元不饱和脂肪酸含量。通过油脂脂肪酸单不饱和脂肪酸、多不饱和脂肪酸和饱和脂肪酸的组成绘制出生物柴油特性三角预测图,为预测生物柴油产品燃料特性提供参考依据。     

分散式固相萃取结合高效液相色谱法快速测定油脂制品中苯并(a)芘

1引言苯并(a)芘(BaP)具有强致癌和致突变作用[1]。油脂制品中的苯并(a)芘主要源自不合理的加工方式:如温度过高的油料焙炒、高温压榨等工艺过程均可导致油脂受热分解,环化聚合生成苯并(a)芘[2]。目前,关于食品中苯并(a)芘较为普遍的检测方法主要有薄层色谱法[3]、高效液相色谱法(HPLC)[4]、气相色谱-质谱法[5]等。提取净化方法主要有凝胶渗透色谱法[6]、液液萃取法[7]、固相萃取法[8]、层析柱法等[9]。本研究采用高效液相色谱荧光检测法,应用分散式固     

华根霉全细胞脂肪酶催化合成生物柴油

比较了5种不同商品化脂肪酶和自制的华根霉CCTCCM201021全细胞脂肪酶(RCL)催化油脂合成生物柴油的转化效果,结果表明,RCL能有效应用于无溶剂体系催化合成生物柴油.在无溶剂体系中对该酶催化生物柴油的转酯化反应工艺进行优化,考察了甲醇用量、体系含水量、酶的添加量和反应温度对生物柴油收率的影响,使生物柴油最终收率大于86.0%.在有机溶剂体系中选择不同有机溶剂作为助溶剂进行转酯化反应,发现logP值在4.0～4.5的有机溶剂具有较好的转化效果.其中以正庚烷为助溶剂的转酯化反应具有最高的生物柴油收率86.7%.在无溶剂体系中RCL催化转化油酸和模拟高酸价油脂合成脂肪酸甲酯的研究表明,该酶具有很好的催化合成生物柴油的潜力.     

固载双功能酸性离子液体催化剂[PSMIM]HSO4/SiO2的制备及其催化制备生物柴油

该大学生创新研究项目以清洁能源为切入点,借助绿色催化剂离子液体催化制备生物柴油。在制备双功能Brönsted酸性离子液体[PSMIM]HSO4的基础上,以多孔氧化硅为载体,采用物理负载法制备固载型催化剂[PSMIM]HSO4/SiO2。并以此为催化剂催化葵花油制备生物柴油,探讨催化剂用量、反应时间、醇油比和反应温度对生物柴油产率的影响。结果表明：醇油比为25：1、催化剂用量为8%、反应温度为160℃、时间为10 h的条件下,生物柴油的转化率达到92.5%。采用FTIR、13C NMR、XRD对催化剂结构进行表征;采用GC-2010气相色谱对生物柴油进行组分分析;并对其密度、运动黏度、凝点等理化性能进行了测定。结果表明所制得的生物柴油基本符合我国生物柴油的标准。本项目的开展不仅在研究成果方面取得了一定的成绩,同时也使学生的创新意识和团队意识,以及教师的教学能力得到提升。     

适应多种原料的生物航煤生产技术的开发

为了减少温室气体排放,扩大航煤的原料来源,生物航煤制备技术的开发受到许多国家的重视.中国石油化工股份有限公司(简称中国石化)开发出了适应多种原料的生物航煤制备技术,该技术以多种生物质油脂为原料,采用加氢法生产生物航煤.针对不同的产品需求,可有不同的产品方案,如最大量生产生物航煤方案,生物航煤兼顾生物柴油方案.以动植物油脂为原料,生物航煤质量收率为35%~45%,生物航煤的冰点可达48℃以下,同时还有7%~11%的柴油馏分和23%~29%的石脑油馏分.中国石化已在工业装置上生产出了符合ASTM D7566-11标准的生物航煤产品,并成功进行了试飞.     

气相色谱法测定生物柴油中甲醇和乙醇的残留量

正生物柴油是由可再生的动植物油脂甲醇(或者乙醇)在催化剂的作用下,经酯交换反应而得到的长链脂肪酸酯,是一种可以替代普通石化柴油的可再生清洁燃料~([1-3])。随着世界范围内车辆的快速增加,柴油的需求量愈来愈大。而石油资源的日益枯竭和人们环保意识的提高,大大促进了世界各国加快柴油替代燃料的开发步伐,生物柴油以其优越的环保性能和可再生性受到各国的重视~([4-6])。醇是生产生物柴油的原料之一,只有在适当的     

废弃油脂生产生物柴油的研究进展

简单介绍了生物柴油的生产原料,综述了用废弃油脂生产生物柴油的现状和方法。废弃油脂生产生物柴油的方法主要有物理法和化学法,物理法主要有掺和法和微乳法,化学法主要有热裂解法和酯交换法。目前生产中采用化学法的酯交换法、以酸碱两步催化法的工艺为主,而生物酶法和超临界法是研究热点。     

废弃油脂原料SRCA生物柴油技术的研发与工业应用示范

针对废弃油脂品质差,酸值高,难于采用传统的碱催化酯交换技术加工生产生物柴油,中国石化石油化工科学研究院开展了超/近临界甲醇介质中油脂溶解和反应的基础研究,相继解决了甲醇与油脂的互溶、降低反应条件,三脂肪酸甘油酯和游离脂肪酸的深度转化,以及产品质量等问题,成功开发了近临界醇解生物柴油技术(以下简称SRCA),于2009年建成了6万吨/年工业化示范装置,以酸化油和餐厨废油为原料,生产连续稳定,产品收率高且满足国家生物柴油质量标准(GB/T20828-2007).     

HPLC-ELSD法测定生物柴油中的游离甘油

采用液液萃取及高效液相色谱-蒸发光散射检测技术,建立了生物柴油中游离甘油含量的测定方法.待测生物柴油经乙腈-水(75:25)抽提并离心分离后,取部分下层水相进行分析.优化的色谱条件为:色谱柱Inertsil NH2 (250 nun ×4.6 mm,5μm );流动相为乙腈-水(75:25);流速1.0 mL/min;...     

原子吸收光谱法间接测定叶酸的含量

在pH5．0的NaOAc-HOAc缓冲溶液中，过量的硝酸银完全沉淀叶酸，用原子吸收光谱法测定剩余的硝酸银，间接计算出叶酸的含量。方法简单快速，回收率在98％～104％之间，相对标准偏差为2．4％。     

Simultaneous determination of creatinine and uric acid in human plasma and urine by micellar electrokinetic chromatography

High performance capillary electrophoresis using a buffer solution containing micelles of ionic surfactant (e.g. sodium dodecyl sulfate), called micellar electrokinetic chromatography, has been applied to the separation and simultaneous determination of creatinine and uric acid in human plasma and urine. The sample was introduced into the capillary by siphoning an appropriate volume of untreated plasma or urine spiked with an internal standard (antipyrine). Creatinine, uric acid, and antipyrine were separated mutually, and from other endogeneous components within 18 min. The calibration plots showed good linearity (correlation coefficient > 0.999) over the concentration range needed for clinical analysis. Standard addition tests indicated that the recoveries of creatinine and uric acid from urine samples ranged, respectively, from 97 % to 106 % and 97.4 % to 108 % with a coefficient of variation (C.V.) of 3.3 % (n = 5), and that those from plasma samples ranged, respectively, from 100 % to 112 % and 101 % to 107 % with a C.V. of 4.7 % (n = 5). The results were in agreement with those obtained by conventional methods.     

Gas chromatographic determination of guanidino compounds in uremic patients using glyoxal as derivatizing reagent

The guanidino compounds guanidine, methylguanidine, guanidinoacetic acid, guanidinopropionic acid, guanidinobutyric acid and guanidinosuccinic acid were eluted and separated after pre-column derivatization with glyoxal from an HP-5 column (30 m × 0.32 mm i.d.) with film thickness 0.25 μm at an initial column temperature of 100 °C for 2 min, with ramping of 20°C/min up to 250 °C and a nitrogen flow rate of 3 mL/min. Detection was by flame ionization detection. Linear calibrations were observed within 0.1-20.0 μmol/L, with limit of detection within 0.024-0.034 μmol/L for each compound. The separation was repeatable with relative standard deviation (RSD) (n = 6) within 1.2-1.8 and 1.1-1.6% in terms of retention time and peak height/peak area, respectively. The method was applied for the determination of the guanidino compounds from serum of uremic patients (n = 7) and healthy volunteers (n = 8), and amounts were observed within 1.33-11.71 and 0.07-0.39 μmol/L with RSD 1.1-3.5 and 1.1-3.0%, respectively. The results were further supported by the standard addition method.     

基于纯水提取的烟熏鲣鱼中肌苷酸的提取方法

建立了一种基于纯水提取的新型烟熏鲣鱼中肌苷酸的提取方法。样品前处理采用95 ℃的纯水作为提取液,提取5 min。采用的色谱条件: 色谱柱为Agilent Zorbax SB-C18柱(150 mm×4.6 mm, 5 μm),柱温为30 ℃,流动相为甲醇-50 mmol/L乙酸铵水溶液(5:95, v/v),流速为1.0 mL/min,检测波长为254 nm。结果表明,该方法测定烟熏鲣鱼中肌苷酸含量的线性范围为1.0～120.0 mg/L;在0.40、2.00、4.00 g/kg (n=3)的添加水平下,回收率为84.6%～100.2%,测定结果的相对标准偏差(RSD)为1.00%～6.12%;检出限(信噪比(S/N)为3)为4 mg/kg;定量限(S/N=10)为12 mg/kg。该方法与常规采用的基于高氯酸的提取方法相比较,提取效率提高了37.0%,并且该方法操作安全、与环境友好,对烟熏鲣鱼中肌苷酸含量测定准确度良好,对其他食品中肌苷酸含量的测定具有借鉴意义,是一种值得推广的样品预处理方法。     

电感耦合等离子体发射光谱法测定银精矿中氧化镁

本文建立了采用直接加混合酸（氢氟酸5mL、硝酸5 mL、盐酸5 mL和高氯酸1mL）酸溶法,10 mL HCL(1:1)提取样品,电感耦合等离子体发射光谱法测定银精矿中氧化镁含量的方法。本方法检出限为0.0016%,测定下限为0.0064%,经富铜(银)矿石成分分析国家标准物质GBW07164验证,相对误差为0.43%;应用于实际样品分析,与标准方法火焰原子吸收光谱法对比,分析结果一致,方法的相对标准偏差（RSD,n=6）均小于4%。方法简便快速准确,结果满意。     

Quantitative determination of melatonin in human plasma and cerebrospinal fluid with high-performance liquid chromatography and fluorescence detection

A validated new and precise reversed-phase high-performance liquid chromatographic method for the determination of melatonin in human plasma and cerebrospinal fluid, with 5-fluorotryptamine as internal standard, is described. Liquid-liquid extraction with dichloromethane was performed under alkaline conditions. After evaporation of the organic solvent, the extract was dissolved in eluent and chromatographed on a base-deactivated octadecyl column, using an eluent composed of 650 mL potassium dihydrogenphosphate solution (0.07 mol/L water), adjusted to a pH of 3.0 with a 43% phosphoric acid solution, mixed with 350 mL methanol. Fluorescence detection at an excitation wavelength of 224 nm and an emission wavelength of 348 nm was used for quantitation. Melatonin and 5-fluorotryptamine chromatographed with retention times of 5.3 and 9. 3 min, respectively. Mean recoveries of 96% (n = 10) and 95% (n = 5) were found for melatonin in plasma and cerebrospinal fluid respectively. 5-Fluorotryptamine was found to have a mean recovery of 90% (n = 10) and 82% (n = 5) in plasma and cerebrospinal fluid, respectively. The repeatability coefficients of variation for both melatonin and 5-fluorotryptamine in plasma were 4-5% [five different samples (r = 5) on two consecutive days (n = 2)], with reproducibility coefficients of 1.6-7% (n = 2, r = 5) and 0.9-4% (n = 2, r = 5) for melatonin and internal standard, respectively. In cerebrospinal fluid the repeatability coefficient of variation of the extraction procedure was 5% (n = 1, r = 5) for melatonin and 7% (n = 1, r = 5) for 5-fluorotryptamine. The correlation coefficients of the calibration curves were 0.9998 (n = 2) in plasma at a concentration range of 0.108-25.9 ng/mL and 0.9994 (n = 2) at a concentration range of 0.108-25.9 ng/mL in cerebrospinal fluid. The limit of detection was determined at 8 pg/mL which enables to measure melatonin concentrations at physiological concentrations reached during daytime.     

电动流动分析-胶束电动毛细管色谱联用测定食品防腐剂

采用电动流动分析(EFA)和胶束电动毛细管色谱(MEKC)联用系统测定了食品中的防腐剂.EFA系统设备简单便携、易于实现自动化.EFA由一台自制电渗泵、5个电磁切换阀(由计算机通过自制接口卡和自编VC语言程序控制)和一个固相萃取微柱组成,采用EFA-MEKC低试剂消耗接口,可减少含贵重试剂的缓冲液消耗.MEKC缓冲溶液为100 mmol/L十二烷基硫酸钠(SDS) 20 mmol/L Na2B4O7(pH 9.3).使用对羟基苯甲酸(PBA)为内标物,方法可在15 min内分离测定6种防腐剂,峰面积相对标准偏差小于3.4%;检出限范围为0.04～0.1 mg/L;实际样品的回收率为91.4%～104%.     

RP-HPLC Determination and Pharmacokinetic Comparison of Cinnamic Acid in Rat Plasma After Administration of Di-Gu-Pi Decoction and Pure Cinnamic Acid

IntroductionTraditionally,Di-Gu-Pi has been used as a naturaltherapeutic agent for the treatment of diabetes,hemor-rhagic inframmation,hypertension,ulcers,and feverunder the guidance of the theory of Traditional ChineseMedicinal(TCM)science[1].This fact h…     

Continuous preconcentration system for nitrate ions using anionic reverse osmosis tubes coupled to an ion chromatograph

A continuous preconcentration system for nitrate ions was developed using cation exchange tubing made from Nafion perfluorosulfonic acid membrane. This method is based on ion exclusion effects and reverse osmosis phenomena. The system was evaluated by connecting it to an ion chromatograph. The concentration ratios could be increased by raising the pressures between the two sides of the cation exchange tubing. Twenty-fold concentration of nitrate ion was achieved when the pump pressure was 20 x 10(5) Pa. The relative standard deviations of the preconcentration ratio at four different pump pressures, 5, 10, 15 and 20 x 10(5) Pa were 1.2-2.8% (n = 5).     

高效液相色谱分析七种氟苯甲酸示踪剂

建立了高效液相色谱法测定7种新型水文示踪剂氟苯甲酸的分析方法。使用C18(150 mm,4.6 mmi.d,5μm)色谱柱、乙腈∶水(磷酸盐)=20∶80(2.56 mmol/L)为流动相、紫外检测器,检测波长223 nm。考察了pH、缓冲溶液浓度、有机相浓度等对保留时间的影响。相对标准偏差1.2%~4.2%,线性范围0.05~5.6μg/L。方法的检出限为0.03~0.07μg/L。平均回收率93.3%~106.6%之间。