Effects of ultrasound intensities on a glycin–maltose model system – a means of promoting Maillard reaction

Effects of ultrasound on pH, intermediate products, browning, maltose content, reducing power and antioxidant activity of a glycin–maltose solution were investigated. Results showed that the ultrasonic treatment at the intensity of 17.83 W cm^?2 for 100 min resulted in the increases of the solution’s absorbance at 294 and 420 nm and the antioxidant activity from approximately 0% to 1.06%, 0.30% and 22.53%, respectively. At the same time, 86.93% reduction in maltose was observed. In addition, little 5‐hydroxymethyl‐2‐furaldehyde was found in HPLC analyses. This study indicated that ultrasound, especially at higher intensities, could potentially be employed as a means to promote the Maillard reaction in the glycin–maltose solution.     

杭州湾南岸滩涂沉积物中HCHs与DDTs污染特征分析

目的 了解六六六(hexachlorocyclohexanes,HCHs)与滴滴涕(dichloro diphenyl trichloroethanes,DDTs)在杭州湾南岸滩涂沉积物中的污染现状.方法 于2018年4月采集杭州湾南岸地区4个采样点不同深度(0～80 cm)滩涂沉积物,利用气相色谱-串联质谱法(gas...     

氟氯苯胺的新合成法及冠醚在其中的应用

以邻二氯苯为原料，经硝化、氟化、还原合成氟氯苯胺．对关键的第二步氟化进行了改进，用１８－冠－６作相转移催化剂，ＤＭＳＯ为溶剂，在（１９０±２）℃反应１ｈ，产率达８９．５％，三步总收率为７６．５％．     

Physiologically based persistent organic pollutant accumulation in pig tissues and their edible safety differences: An in vivo study

As one of the most important animal food sources, pigs are an important model in the assessment of human exposure to persistent organic pollutants (POPs). In the present study, the distribution of the administrated polychlorodibenzo-p-dioxin/furan (PCDD/F)–polychlorinated biphenyl (PCB) mixture and polybrominated diphenyl ethers (PBDEs) in the different tissues of pigs, including liver, lung, kidney, subcutaneous fat, mesentery and muscle, for understanding the physiologically based pollutant accumulation in these tissues and their edible safety was investigated. It was found that liver had a much higher potential to accumulate PCDD/Fs and dioxin-like pollutants like PCB-126 than the other tissues, but it did not specifically concentrate PBDE congeners as compared to the other tissues. The different PCDD/F congeners and PCB-126 followed a similar distribution pattern in the different tissues; also the different PBDE congeners have the similar pattern in these tissues. The liver’s higher concentrating potency for dioxin-like pollutants may result from its detoxification function, however, it can concentrate dioxin-like pollutants but not PBDEs may suggest that it is the toxicity but not lipophilic property of these POPs dominated their accumulation in liver tissues. Also the result suggested that liver is a high-risk edible tissue for dioxin-like pollutants. In conclusion, the present study suggested that physiologically based assessments are necessary for evaluating edible tissue safety in animal source foods.     

高效液相色谱法测定竹筷中噻苯咪唑、邻苯基苯酚和联苯

建立高效液相色谱测定竹筷中噻苯咪唑、邻苯基苯酚、联苯的方法。以甲醇为提取溶剂,用索氏提取法提取竹筷中噻苯咪唑、邻苯基苯酚和联苯3种保鲜剂。以甲醇-水(体积比70:30)为流动相,流速1.0mL/min,采用C18柱(250mm×4.6mm,5μm)分离,紫外检测器检测,检测波长247nm,进样量20μL。方法的相关系数均大于0.999,最低检出限为0.01μg/mL,平均回收率为95.8%～97.1%,相对标准偏差为1.4%～2.6%。应用所建立的方法测定一次性竹筷中噻苯咪唑、邻苯基苯酚、联苯的残留量,结果表明：该方法样品处理简单,色谱分离完全,结果准确可靠,适于竹筷中噻苯咪唑、邻苯基苯酚和联苯的分析检测。     

气相色谱测定小麦和稻米中11种多溴联苯醚

目的 建立气相色谱-电子捕获检测器法测定小麦和稻米中11种代表性多溴联苯醚的分析方法。方法 小麦粉或糙米粉经水化后,采用乙酸乙酯提取和5 g酸性硅胶(44%, m:m)固相净化柱净化,使用气相色谱-电子捕获检测器进行检测,外标法定量。结果 小麦和稻米中,11种多溴联苯醚的定量线性范围分别为0.1~50.0 ng/g,0.2~50 ng/g,0.5~50 ng/g,回归系数均大于0.998;方法检出限在0.03~0.15 ng/g之间,定量限为0.1~0.5 ng/g之间;方法回收率为66.9%~93.5%,相对标准偏差为0.4%~17.8%。结论 本方法的样品前处理简单,对仪器要求低,准确度和精密度较好,适用于小麦和稻米中多溴联苯醚的检测分析。     

碳酸二甲酯与苯酚酯交换合成碳酸二苯酯研究

选择Lewis酸催化剂、分子筛催化剂、有机钛和锡化合物催化剂和不同负载型金属氧化物催化剂用于碳酸二甲酯(DMC)与苯酚酯交换合成碳酸二苯酯(DPC)的过程。试验结果表明,：MoO3/SiO2和TiO2／SiO2催化剂对该反应具有相对较好的催化活性和选择性。以MoO3／SiO2为催化剂,DMC转化率和DPC选择性分别为24.3％和37.6％;以TiO2／SiO2,为催化剂,DMC转化率和DPC选择性分别为13.7％和20.0％。在该酯交换反应中,SiO2与Al2O3和MgO相比,是一种良好的催化剂载体。     

钯负载锰氧化物基双金属复合氧化物催化氧化羰基化合成碳酸二苯酯

采用共沉淀法分别制备锰掺杂钨、钒、铋3种双金属复合氧化物载体,以氯化钯为活性组分制备负载型催化剂,并用于苯酚氧化羰基化合成碳酸二苯酯（DPC）。通过气相色谱（GC）、X射线衍射（XRD）、氢气程序升温还原（H₂-TPR）、X射线光电子能谱（XPS）等表征手段,对催化剂结构和性能进行表征。结果表明:钨-锰载体随掺杂比例和焙烧温度升高,逐步形成四氧化三锰晶粒,同时钨渗入锰氧化物晶格中,在掺杂比（物质的量比）为1:1、焙烧温度为600 ℃条件下制备的催化剂性能最佳,DPC收率为5.20%;钒-锰载体在焙烧温度为400 ℃、掺杂比为1:5条件下形成二氧化锰晶相,催化剂性能明显提高,DPC收率为10.46%,而较高的焙烧温度会破坏晶型的完整;铋-锰载体在掺杂比为1:5、焙烧温度为400 ℃条件下制备的催化剂催化效果最好,DPC单程收率可达到13.13%。     

高效液相色谱法测定二苯硫脲含量

建立了外标法分析对称二苯硫脲含量的高效液相色谱分析方法。色谱柱为菲罗门Hydro-RP柱（250 mm×4.6 mm,4μm）;流动相为甲醇-水混合溶液;检测波长：272 nm;流速：0.8 mL/min;进样量：20μL,保留时间约8.0 min。利用该方法对二苯硫脲进行分析,线性关系良好,相关系数为0.9998,相对标准偏差为1.9%,回收率为99.58%～101.23%,最小检出限14 ng。该方法具有快速、准确、简便等特点。