利用超声雾化-固相萃取法萃取,气相色谱法和气相色谱-质谱法测定了小茴香中的挥发油.采用正十四烷作为洗脱溶剂,体积为50μL、吹扫气流速为200 m L/min,吹扫时间为5 min.利用优化后的方法测定了小茴香中挥发性成分的种类和含量,与水蒸...利用超声雾化-固相萃取法萃取,气相色谱法和气相色谱-质谱法测定了小茴香中的挥发油.采用正十四烷作为洗脱溶剂,体积为50μL、吹扫气流速为200 m L/min,吹扫时间为5 min.利用优化后的方法测定了小茴香中挥发性成分的种类和含量,与水蒸馏提取法所得结果相似.测定样品溶液中挥发性成分的回收率为65.8%~102.0%,相对标准偏差小于8.0%.展开更多
The blocking reaction of polyisocyanates with active hydrogen containing subs tances and the deblocking of the reaction products have been investigated by IR and TGA. The results showed that the initial deblocking tem...The blocking reaction of polyisocyanates with active hydrogen containing subs tances and the deblocking of the reaction products have been investigated by IR and TGA. The results showed that the initial deblocking temperature of the blocked polyisocyanates were mainly determined by active hydrogen substances. The deblocking temperature of toluene diisocyanate blocked with methylethylketoxime was 110 ℃ and this temperature could be more or less reduced by using organic tin catalyst at deblocking reaction.展开更多
文摘利用超声雾化-固相萃取法萃取,气相色谱法和气相色谱-质谱法测定了小茴香中的挥发油.采用正十四烷作为洗脱溶剂,体积为50μL、吹扫气流速为200 m L/min,吹扫时间为5 min.利用优化后的方法测定了小茴香中挥发性成分的种类和含量,与水蒸馏提取法所得结果相似.测定样品溶液中挥发性成分的回收率为65.8%~102.0%,相对标准偏差小于8.0%.
文摘The blocking reaction of polyisocyanates with active hydrogen containing subs tances and the deblocking of the reaction products have been investigated by IR and TGA. The results showed that the initial deblocking temperature of the blocked polyisocyanates were mainly determined by active hydrogen substances. The deblocking temperature of toluene diisocyanate blocked with methylethylketoxime was 110 ℃ and this temperature could be more or less reduced by using organic tin catalyst at deblocking reaction.