离子色谱－电感耦合等离子体质谱法联用测定饮料中的溴形态

建立离子色谱(IC)进行分离、电感耦合等离子体质谱仪(ICP-MS)作为检测器测定饮料中溴酸根与溴离子的方法。溴酸根与溴离子的检出限分别为0.1μg/L 和0.2μg/L。根据加标回收的方法评价该方法的准确性,溴酸根的加标回收率为88.1%～106.4%,相对标准偏差为1.52%～3.83%(n=6)。根据所建立的方法,分析市售部分饮料中溴酸根的含量,其中溴酸根均未检出。     

Nano-silica particles enhanced adsorption and recognition of lysozyme on imprinted polymers gels

Molecular imprinting technology has a great potential to be used in protein separation and purification.In this work,lysozyme imprinted polyacrylamide gel was prepared with silica particles as a sacrificial template to generate macro-porosity for fast adsorption.The adsorption equilibrium time and adsorption capacity were 9 h and 56 mg/g respectively,which was 2 h less and 2.3-fold more than polymers without the sacrificial template.In order to test molecular imprinting polymers(MIPs)'selectivity,bovine serum albumin(BSA)was chosen as interferent for binary adsorption tests.In addition,the adsorption selectivity was further investigated using different molar ratios of lysozyme to BSA with fixed total concentration of proteins,as well as using various total concentrations of proteins with an equimolar ratio of lysozyme to BSA.It has been proven that the total concentration of proteins should be larger than1.5×10~(-7) mol/mL,when the molar ratio of BSA to Lyz is 1∶1,in order to effectively separate Lyz from the binary protein mixture.The macro-porous lysozyme molecularly imprinted polymers have less adsorption time,larger adsorption capacity,and better imprinting effect.     

黄化变异对英红九号红茶香气的影响

英红九号的黄化变异植株嫩梢存在叶绿体发育缺陷,叶片光合作用与代谢积累的改变或会影响茶叶品质。为明确黄化变异对红茶香气的影响,本文分别以黄化变异和叶色正常英红九号为原料加工试验和对照红碎茶,比较样品间感官香气与化合物的变化。感官审评结果表明,黄化红碎茶的香气浓度整体弱于对照,尤其在甜度与鲜度上。利用顶空固相微萃取和气相色谱-串联质谱法,从两组样品中鉴别出56种香气化合物。依据出现频次和单因素方差分析筛选出49种差异成分,随后进行化学计量分析与基于衍生途径的分类。结果表明,利用49种化合物作为主成分能清晰区分两组样品;10种化合物有组成差异,其中黄化样品的香气种类较少;39种化合物有含量差异,其中28种化合物在黄化样品中显著下降,11种上升。差异香气主要涉及脂肪酸、类胡萝卜素氧化和萜类代谢相关的衍生途径。