液相色谱法测定地表水中氯酚类化合物

采用单滴液相微萃取-高效液相色谱法测定水中的4-氯酚、2,6-二氯酚、2,4-二氯酚和2,4,6-三氯酚。色谱条件为:Diamonsil C18柱(250×4.6mm i.d.,5μm),柱温:室温,流速1.0mL/min,以甲醇∶水∶甲酸(体积比70∶30∶0.2)为流动相,225nm紫外检测。考察了萃取溶剂种类、萃取时间、萃取温度、搅拌速度和pH值对萃取效率的影响。4-氯酚、2,6-二氯酚、2,4-二氯酚在1.5~100mg/L和2,4,6-三氯酚在2.5~100mg/L范围内有良好线性,相关系数不低于0.9996,回收率在74.9%~84.4%之间,相对标准偏差低于4.9%。     

Preparation of Polystyrene/Triphenyl Phosphate Composites by Suspension Polymerization and Melt Extrusion Method——A Comparative Study

Polystyrene (PS)/triphenyl phosphate (TPP) composites were prepared by both suspension polymerization and melt extrusion, and a comparative study of the flame retardance and mechanical properties was carried out. The results showed that suspension polymerization was a better technique than melt extrusion for obtaining good dispersity of the PS/TPP composite. The TPP nanoparticles, which were approximately 50 nm in size, were homogenously and uniformly dispersed in the PS matrix by suspension polymerization in one-step. However, the PS/TPP composite was partially agglomerated, exhibiting irregularly shaped micron-scale particles as a result of melt extrusion. In contrast to the melt extrusion, the limited oxygen index (LOI) of the PS/TPP nanocomposite by suspension polymerization increased to 22.6% from 21.8%, and time to ignition (TTI) increased by 12.3%, the peak heat release rate (PHRR) decreased by 8.5%, and the total heat release (THR) decreased by 11.0%. The mechanical properties of the PS/TPP nanocomposite by suspension polymerization also increased. The tensile strength, elongation at break, and flexural strength increased by 36.4%, 8.5%, and 108%, respectively.     

多面体低聚八硝基苯基硅倍半氧烷纯度分析

使用高效液相色谱-电喷雾四级杆飞行时间质谱(HPLC-ESI-Q-TOF MS)联用技术对八硝基苯基硅倍半氧烷(ONPS)纯度进行分析,从而判定ONPS产物峰及杂质峰的位置,根据ONPS峰和杂质峰的面积比计算ONPS的纯度.通过改变HPLC的洗脱梯度和测试时间,将ONPS产物中的杂质峰完全分开,测得硝基苯基硅倍半氧烷(NPS)质量分数为97.55%,其中ONPS的纯度约为92.42%,产物中含有九硝基八苯基硅倍半氧烷(9-NPS)约5.13%,其它杂质含量约为2.45%.通过对ONPS高效液相色谱图峰形和同分异构体极性情况分析,进一步证明ONPS分子中硝基取代发生于对位和间位.使用超高效液相色谱(UPLC)对ONPS进行分析,以更高的分离效率验证了HPLC的结果.该方法可作为ONPS纯度的分析方法.     

低温冷冻萃取-色谱法测定芝麻糊中苯脲除草剂

低温冷冻萃取,结合高效液相色谱法,测定芝麻糊中的甲氧隆、灭草隆、绿谷隆、溴谷隆、敌草隆、利谷隆和枯草隆。乙腈为萃取剂,考察了盐效应、冷冻时间、萃取剂用量等条件对萃取结果的影响。优化条件下,7种除草剂的加标回收率分别为92.4%、106.3%、106.4%、95.2%、96.9%、94.4%、90.6%,相对标准偏差(RSDs)2.8%~7.4%。