碳酸二苯酯中微量杂质的高效液相色谱分析

碳酸二苯酯和双酚A产生酯交换和缩聚反应,制得聚碳酸酯.聚碳酸酯耐压、透明性好,在机械制造、电子电器、军事及照明工业.安全与医疗器械等许多方面有着广泛的用途,是一种性能优良的工程塑料.聚碳酸酯的色泽与许多因素有关.由于原料碳酸二苯酯在制造过程中,一些沸点与之相近的杂质极易残留在产品里.要想得到高质量的聚碳酸酯,必须使其每一种杂质含量控制在100μg/g以下.至今未见报道同时检测碳酸二苯酯中3种微量杂质的分析方法.因此,本文结合单位工艺研究建立了一种用液相色谱进行分析的方法.     

酸碱指示剂的代用品植物色素的探讨

在化学实验中常用指示剂检验溶液的酸碱性。实际上用植物色素的浸取液代替酸碱指示剂,也能取得很好的实验效果。     

饮料中4种人工合成甜味剂同时测定的超高效液相色谱快速检测方法

建立了采用超高效液相色谱同时测定饮料中4种甜味剂(安赛蜜、糖精钠、甜味素、纽甜)的方法。样品经简单的预处理后,通过ACQUITY UPLCTM BEH C18色谱柱分离,以乙腈-20 mmol/L磷酸二氢钠水溶液为流动相进行梯度洗脱,于220 nm波长下紫外检测。一次进样分析仅需6 min。4种甜味剂在0.5～20.0 mg/L范围内的线性关系良好,在加标水平为1,10和20 mg/L时,被测物的回收率为80.5%～95.2%,相对标准偏差为0.50%～8.7%。     

2,7-二芳基呫吨螺芴二醇衍生物的合成

以2,7-二溴-9-芴酮、间苯二酚和苯硼酸的衍生物为原料,经过环化、羟乙基化和Suzuki偶联等3步反应,设计并合成了一系列2,7-芳基呫吨螺芴二醇衍生物,通过红外光谱、核磁光谱(¹H NMR,¹³C NMR)、元素分析等表征了化合物的结构。折光率和紫外可见光谱测试结果表明：与2,7-无取代基的呫吨螺芴二乙醇衍生物相比,目标化合物具有更高的折光率(1.66～1.68)和良好的透光率,有望作为聚碳酸酯光学树脂的二醇单体,应用于光学透镜、光学膜等领域。     

饮料中4种人工合成甜昧剂同时测定的超高效液相色谱快速检测方法

建立了采用超高效液相色谱同时测定饮料中4种甜味剂(安赛蜜、糖精钠、甜味素、纽甜)的方法.样品经简单的预处理后,通过ACQUITY UPLCTM BEH C18色谱柱分离,以乙腈-20 mmol/L磷酸二氢钠水溶液为流动相进行梯度洗脱,于220 nm波长下紫外检测.一次进样分析仅需6 min.4种甜味剂在0.5～20.0 mg/L范围内的线性关系良好,在加标水平为1,10和20 mg/L时,被测物的回收率为80.5%～95.2%,相对标准偏差为0.50%～8.7%.     

Carbonized cotton fibers via a facile method for highly sensitive solid‐phase microextraction of polycyclic aromatic hydrocarbons

Cotton fiber is an environmentally friendly and natural material with a certain extraction capacity, while its enrichment ability is poor. In order to improve the extraction efficiency of cotton fibers, it was carbonized to form a layer of amorphous carbon as the sorbent by a simple carbonization method. Carbonized cotton fibers were filled into a polyetheretherketone tube for in‐tube solid‐phase microextraction. The carbonization time was investigated to obtain high extraction efficiency. Coupled to high‐performance liquid chromatography, the extraction tube was evaluated with polycyclic aromatic hydrocarbons, estrogens and phthalates, and it exhibited best extraction efficiency for polycyclic aromatic hydrocarbons. Under the optimum conditions, an online analysis method for several polycyclic aromatic hydrocarbons was established with large linear ranges (0.016–0.20 μg/L), low limits of detection (0.005–0.020 μg/L), and high enrichment factors (948–2874). Analysis method was successfully applied to the detection of targets in the real samples and shown satisfactory durability and chemical stability. Moreover, the relative recoveries ranged from 82 to 119.2%, which demonstrated the applicability of carbonized cotton fibers in sample preparation. Compared with other reported methods, the proposed method provided shorter extraction time, higher enrichment factors, comparable limits of detection, and recoveries.     

N‐Heterocyclic Carbene Catalyzed Enantioselective α‐Fluorination of Aliphatic Aldehydes and α‐Chloro Aldehydes: Synthesis of α‐Fluoro Esters,Amides, and Thioesters

The asymmetric fluorination of azolium enolates that are generated from readily available simple aliphatic aldehydes or α‐chloro aldehydes and N‐heterocyclic carbenes (NHCs) is described. The process significantly expands the synthetic utility of NHC‐catalyzed fluorination and provides facile access to a wide range of α‐fluoro esters, amides, and thioesters with excellent enantioselectivity. Pyrazole was identified as an excellent acyl transfer reagent for catalytic amide formation.     

高效液相色谱法同时测定肉制品中的6种食品添加剂

建立了同时测定肉制品中化学性质差异较大的6种常用食品添加剂的高效液相色谱(HPLC)分析方法。根据6种添加剂(苯甲酸(钠)、山梨酸(钾)、糖精钠、安赛蜜、诱惑红和胭脂红)的化学性质,对HPLC分析条件进行了详细的优化。结果表明:以ZORBAX Eclipse Plus C18柱(150mm×4.6mm,5μm)为分析柱,以甲醇和20mmol/L醋酸铵溶液(pH为6.9)为流动相进行梯度洗脱,在235nm波长下进行检测,可以在18min内完成6种添加剂的同时测定。在高、低两个加标浓度下,样品的回收率为80.7%～94.4%,相对标准偏差(n=3)为2.0%～7.1%。结果表明,该方法快速、准确,能够同时分析测定肉制品中上述6种食品添加剂。     

钼蓝光度法快速测定钼铁中的硅

通过适当的溶样方法将钼铁试样溶解,使其中的硅转化为正硅酸,在一定的酸度条件下,加入钼酸铵与其反应生成硅钼黄,再用草酸-硫酸亚铁铵还原法将硅钼黄还原成硅钼蓝,进行比色分析.该方法可以测定钼铁中5%以下的硅含量,测定结果和重量法测定结果相符合,相对标准偏差为0.43%(n=4).