电纺聚苯乙烯纳米纤维固相萃取-气相色谱质谱法测定复合膜袋中27种芳香胺的迁移量

目的 建立电纺聚苯乙烯纳米纤维固相萃取-气相色谱质谱法测定复合膜袋中27种芳香胺的迁移量的方法.方法 样品经活化的、由电纺纳米聚苯乙烯材料制作的固相萃取小柱上样后,使用叔丁基甲醚洗脱,采用程序升温进样口进样.采用气相色谱质谱法(gas chromatography mass spectrometry,GC-MS)测定复...     

Pd／C催化剂的表征及其制备条件对脂肪腈加氢催化的影响

通过浸渍法制备了负载型钯炭催化剂并用于脂肪腈加氢催化制备单烷基二甲基叔胺，并使用N2-吸附、透射电子显微镜、X射线衍射等测试手段对催化剂进行物性表征，而且用气相色谱对叔胺产品进行定性定量分析。通过制备条件的优化，选定了pH值为7．90、浸渍时间15h，并且在反应温度120℃、反应时间5h、二甲胺间歇式进料的反应条件下，叔胺含量可以高达98．6％，说明浸渍法制备的钯炭催化剂，作为脂肪腈加氢催化制备叔胺的催化剂，其活性较高。     

食源性乳酸菌安全性的评价

从不同来源的样品中分离得到36 株乳酸菌,对其进行常见抗生素如氯霉素、四环素、红霉素抗药性分析,结果表明,26 株菌具有抗药性,其中4 株携带抗生素抗性基因,并且菌株Enterococcus faecium KN9所携带的四环素抗性基因tet（M）和tet（L）能通过接合作用,转移到受体菌Lactococcus lactis MG1614中。对这些乳酸菌产生有害代谢产物分析结果表明,部分菌株可以产生生物胺,所有的菌株都不产生硝基还原酶和偶氮还原酶。所以,本实验分离到的大部分乳酸菌是安全的,只有携带有抗四环素基因的E. faecium KN9具有潜在的安全隐患。因此,需要在食用前对乳酸菌进行安全性评价,以减少可能的安全隐患。     

葡萄酒中生物胺含量的影响因素研究

研究了葡萄酒生产过程中影响生物胺产生量的主要因素,结果表明,葡萄酒酒精发酵和苹果酸．乳酸发酵过程均有牛物胺的产生,影响葡萄酒中生物胺产生的主要因素是乳酸菌中氨基酸脱羧酶的活性,本研究添加了氨基酸脱羧酶辅酶的样品与对照相比,生物胺含量提高了90．6％。酵母菌和乳酸菌种类、酒精发酵温度,生物胺前体物质也是影响生物胺含量的主要因素,发酵温度越高、生物胺产生量越;在一定范围内,氨基酸的浓度越大产生物胺越多。但酵母菌和乳酸菌的添加量对生物胺浓度的影响较小。     

亲水作用色谱-电喷雾串联质谱法测定水产品中的氟苯尼考胺的残留量

建立亲水作用色谱-电喷雾串联质谱测定水产品中氟苯尼考胺残留量的测定方法。样品用碱性乙酸乙酯提取,以正己烷和脂肪吸附材料去除油脂,用5 mmol/L乙酸铵溶液(含0.2%甲酸)和乙腈作为流动相,以梯度洗脱方式在Acquity UPLC BEH HILIC柱(55 mm×2.1 mm,1.7μm)色谱柱上分离,以电喷雾离子源正离子模式进行质谱分析,基质外标法定量。结果表明,氟苯尼考胺的质量浓度在0.1~20μg/L范围内呈良好的线性,相关系数(r2)大于0.990。在1.0~50.0μg/kg加标水平下,虾、黄鱼、鳗鱼、烤鳗的平均回收率为70.5%~87.7%,相对标准偏差为4.8%~11.6%,定量限为1.0μg/kg。该方法简单、灵敏、稳定,可满足水产品中氟苯尼考胺残留量的检测和确证需要。     

聚醚胺页岩抑制剂抑制性能研究

以聚醚胺为钻井液用页岩抑制剂,通过相对抑制率实验、抑制膨润土造浆实验考察了其页岩抑制性能.结果表明,聚醚胺浓度越大,相对抑制率越高,浓度大于0.5％时,相对抑制率不再变化,抑制性能优于5％ KCl.抑制膨润土造浆实验中,浓度越高,动切力越小,抑制造浆能力越强.加入聚醚胺的泥浆在100～180 ℃下老化16 h后,相对抑制率均在90％以上,抗温性能良好.加入不同浓度的NaCl(1％～36.5％)或CaCl2(1％～5％)老化16h后,流变参数变化不大,相对抑制率均在95％以上,抗盐性能良好.     

氧化叔胺合成条件的优化

通过Ｌ３（３）正交试验，对双氧水氧化法合成氧化叔胺的工艺条件进行了优化研究，测试了反应温度、反应时间和双氧水过量比对产物得率的影响。从而获取了在有机酸值化作用下的最佳工艺条件为：反应温度７５℃，反应时间１２ｈ，双氧水过量１５％，在此条件下重复试验，均可使最终氧化叔胺收率≥９５％，从而为该表面活性剂的工业生产提供了可靠的工艺参数。     

端氨基超支化聚酰胺—胺皮革游离甲醛捕获剂的合成

以二乙烯三胺和丁二酸酐为单体,四氢呋喃为溶剂,低温下合成结构中含一个羧基、2个氨基的AB2型单体,再以逐步滴加AB2型单体的方式熔融聚合得到端氨基超支化聚合物;以红外光谱、核磁共振对聚合物结构进行了表征;以GPC测定了聚合物分子质量;将合成的聚合物用做皮革甲醛捕获剂,结果表明:当捕获剂加入量为皮质量的4.0%时,配合水洗工艺,最终能将皮革中的甲醛含量由约560mg/kg降低至280mg/kg,且对皮革具有良好的助染效果。     

Free radical-scavenging activity of nonenzymatically-browned phospholipids produced in the reaction between phosphatidylethanolamine and ribose in hydrophobic media

The reaction of phosphatidylethanolamine (PE) and ribose (RI) in olive oil was studied in an attempt to both explore the possibilities of producing Maillard reaction in hydrophobic media and analyse the antioxidant properties of the formed compounds. When oil samples containing PE/RI mixtures were heated at a temperature higher than 90 °C, the oil rapidly developed browning, fluorescence, and free radical-scavenging activity, which was higher than the developed by the oil in the absence of added compounds or in the presence of only either PE or RI. These changes were a consequence of the formation of Maillard reaction products in the oil by reaction between PE and RI. Among them, the N-alkylpyrrole derivatives produced in this reaction could be determined by GC–MS after transpyrrolisation. Differently to Maillard products formed between carbohydrates and amino acids, the products of the reaction with aminophospholipids are more hydrophobic and, therefore, better candidates to be employed as lipophilic antioxidants in food products. Because of the different polarity of Maillard products between carbohydrates and either amino acids or aminophospholipids, Maillard reaction can be a useful procedure to obtain a wide range of antioxidants with different polarities to be employed in different food systems.     

Determination of pesticide residues in food matrices using the QuEChERS methodology

The determination of pesticide residues in food matrices is a formidable challenge mainly because of the small quantities of analytes and large amounts of interfering substances which can be co-extracted with analytes and, in most cases, adversely affect the results of an analysis. However, safety concerns require that pesticides of the wide range of chemical properties (including acidic, basic and neutral) should be monitored. Because of the wide variety of food matrices, the sample must initially be cleaned up before final analysis. That is why the analytical chemist is faced with the need to devise new methodologies for determining such residues to be determined in a single analytical run. To accomplish the goal, QuEChERS methodology has been developed. It is a streamlined and effective extraction and cleanup approach for the analysis of diverse analyte residues in food matrices. So far, there have been achieved promising results by liquid or gas chromatography analysis, including pesticides, but also acrylamide, pharmaceuticals and veterinary drugs.