利用GPC法测定PET的平均分子量

利用凝胶色谱(GPC)法测定PET的分子量及其分子量分布,方法可靠,数据合理,为PET的纺丝加工提供了有效的参考数据。     

The influence of macromolecular architecture on the critical aggregation concentration of large amphiphilic starch derivatives

A range of hyperbranched emulsifiers were prepared by reaction between starch and 2-octen-1-yl succinic anhydride (OSA, commonly used in the food industry), under slightly basic conditions in water, leading to starches bearing hydrophobic OSA groups randomly distributed along the chains. By using different starch backbones and varying the amount of OSA during the synthesis, amphiphilic OSA-modified starches were obtained that formed aggregates in water and having controlled structural parameters. These parameters were characterized using ¹H NMR, multiple-angle laser light scattering and size-exclusion chromatography. The critical aggregation concentration (CAC) was measured for samples with different levels of OSA modification, of macromolecular size and degree of starch branching. Increasing the dispersity in macromolecular size and/or degree of OSA substitution noticeably decreased the CAC. The results are interpreted in terms of the branching structure and conformation of the modified starches: all findings can be understood in terms of the various influences of molecular size, composition and flexibility. The structural factors affecting the CAC of large hyperbranched surfactants are found to be similar to those seen with smaller and simpler branched synthetic surfactants.     

GPC净化联合GC-MS/MS测定番石榴中2种杀菌剂残留

建立同时测定番石榴中三唑酮和腐霉利的气相色谱-串联质谱(GC-MS/MS)分析方法。番石榴样品经乙腈提取,凝胶渗透色谱净化,GC-MS/MS检测,外标法定量。结果表明:三唑酮和腐霉利在0.05~0.50 mg/kg范围内,回收率在77.4%~100.7%之间,相对标准偏差为5.0%~9.6%(n=5)。三唑酮、腐霉利定量限分别为0.01和0.005 mg/kg。该方法灵敏、准确,适用于番石榴中2种杀菌剂的残留检测分析。     

电动汽车驱动系统广义预测控制

为了柔化电动汽车运行时速度变动带来的冲击,采用了单变量隐式广义预测控制的方法对电机电流进行控制,提出了一种基于车辆变速舒适度控制的加速度模型。在对电动汽车用永磁同步电动机驱动系统分析的基础上,建立了控制对象受控自回归滑动平均模型;为了避免系统参数变化引起的模型失配,采用递推最小二乘法对模型参数进行了辨识,并对电动汽车的启动和变速过程进行了仿真,得到了速度、加速度曲线。仿真结果表明,在变速始端和末端,加速度和加加速度均趋于零,说明了该方法能够实现对电动汽车变速过程的有效控制且鲁棒性强,具有实用价值。     

乙烯-乙烯醇共聚物(EVOH)的辐射效应研究

用凝胶抽提、凝胶渗透色谱以及傅立叶变换红外光谱等方法研究了两种乙烯-乙烯醇共聚物（Ethylene-vinyl alcohol copolymers,EVOH）本体和E151／甘油体系的室温辐射效应。在氮气保护下,试样在^60Co源中的吸收剂量最高达到1800kGy。结果显示,EVOH在室温下是一种十分难交联的聚合物。E151本体（乙烯醇摩尔分数56％）在吸收剂量达到800kGy时出现痕量凝胶,当吸收剂量增至1200kGy时,体系凝胶含量也只有5．9％。而F101本体（乙烯醇摩尔分数68％）在1800kGy才出现痕量凝胶。造成这两种EVOH的凝胶化剂量不同的原因是乙烯醇基含量不同。EVOH在辐照过程会产生共轭双键,其含量在辐照初期随吸收剂量的增加而增大,达到最大值后随吸收剂量的增加而减少。双键的存在促使EVOH产生了交联。加入增塑剂甘油后,体系在800kGy以前与本体一样无凝胶,而在800kGy之后凝胶含量随着吸收剂量的增大而增大,且比本体E151的凝胶含量值大。     

Evaluation of polyphosphoric acid on the performance of polymer modified asphalt binders

The aim of this research is to evaluate the effect of polyphosphoric acid (PPA) on the mechanical performance of styrene–butadiene–styrene (SBS) and styrene–butadiene–rubber (SBR) modified asphalt. Conventional properties, multiple stress creep recovery (MSCR), bending beam rheometer (BBR), and linear amplitude sweep (LAS) tests were conducted to evaluate the performance characteristics of asphalt at different PPA inclusions. Gel-permeation chromatography (GPC), saturates, aromatics, resins, and asphaltenes (SARA), and Fourier transform infrared (FTIR) were carried to reveal the molecular weight, component and infrared spectra of asphalt. Results showed that PPA hardened the asphalt, improved the rutting and fatigue performances of polymer modified asphalt (PMA) binder, but weakened the anti-cracking performances. Besides, storage stability had a significant improvement as the addition of PPA. The addition of PPA brought more macromolecules into asphalt and led to more high-average molecular weight compounds. Furthermore, PPA changed four component ratios of asphalt. Both PMA with or without PPA have similar absorption peaks. This may be due to absorption peak of PMA covered the changes in PPA modification process as the low content of PPA. 0.8% dosage of PPA may be considered optimum for composite modified binder combining the above experimental results for this binder source.     

凝胶渗透色谱净化超高效液相色谱法测定 辣椒油和火锅底料中的10种工业染料

目的建立辣椒油和火锅底料中的10种工业染料的检测方法。方法采用凝胶渗透色谱仪作为前处理设备,采用超高效液相色谱仪作为检测设备,对高脂肪含量的辣椒油及火锅底料等辣椒制品中的10种红黄类工业染料进行检测,并对方法的有效性进行验证。结果以空白的辣椒油和火锅底料为基质,分别在高、中、低三个水平进行加标实验,回收率分别在56.0%~96.4%之间和70.0%~98.2%之间,RSD(n=6)分别为1.9%~8.2%之间和1.8%~7.9%之间,各工业染料的检出限(S/N=3)在0.009~0.051 mg/kg之间,定量限(S/N=10)在0.030~0.153 mg/kg之间。结论该方法操作简单,稳定性好,适于在实际检测工作中推广应用。     

同位素稀释凝胶渗透色谱-气相色谱-质谱法测定膳食样品中16种邻苯二甲酯类物质

建立膳食样品中16种邻苯二甲酸酯的同位素稀释凝胶渗透色谱净化(GPC)-气相色谱(GC)-串联质谱(MS)检测方法。方法 加入同位素内标的膳食样品用正己烷饱和过的乙腈超声提取,GPC净化,DB-5ms 毛细管色谱柱分离(30m×0.25mm,0.25μm),GC-MS选择离子监测模式(SIM)测定,内标法定量。结果 16种邻苯二甲酸酯在8类膳食样品中的平均添加回收率为52.3%～124.7%;RSD为1.6%～16.2%;检出限为0.03～0.06mg/kg。结论 该方法简便、灵敏、准确,适用于膳食样品中邻苯二甲酸酯的检测。     

银杏淀粉的分离和纯化

用重结晶法可以得到纯度较高的银杏直链淀粉和支链淀粉。凝胶过滤色谱表明：银杏直链淀粉的分子量比玉米直链淀粉的小,而支链淀粉的分子量则具有较宽的分布。银杏直、支链淀粉的碘亲和力分别为19．19％和0．13％,蓝值分别是0．85和0．12,γmax为626nm和564nm;银杏淀粉中直链淀粉含量为33％。     

超高效液相色谱-质谱联用法快速测定豆酱中PC、LPC和GPC的含量

建立快速、简单、准确测定豆酱中活性成分磷脂酰胆碱(PC)与其降解产物溶血磷脂酰胆碱(LPC)和甘油磷脂酰胆碱(GPC)含量的超高效液相色谱-质谱联用(UPLC-MS)分析方法。将豆酱样品经过预处理后,以乙腈、醋酸铵为流动相,使用Waters ACQUITY UPLC超高效液相色谱仪,经ACQUITY UPLC BEH HILIC色谱柱(2.1×100mm,粒径1.7μm)分离,利用质谱定性定量测定其含量。质谱在电喷雾正离子模式下,对m/z782、m/z520和m/z258进行选择离子监测。该方法下PC、LPC和GPC分别在0.191～1.910μg/mL,0.236～2.360μg/mL和0.016～0.160μg/mL范围内峰面积和浓度呈良好的线性关系,相关系数R2PC=0.9959、R2LPC=0.9986和RG2PC=0.9991;PC、LPC和GPC的最低检测限分别为0.05、0.07、0.005μg/mL,最低定量限分别为0.19、0.24、0.016μg/mL;方法的平均回收率为93.2%～97.8%,相对标准偏差为1.5%～3.5%。此方法准确,灵敏度高,样品处理简单,分析时间短,可快速测定豆酱中PC与其降解产物LPC和GPC含量。