Analysis of amphetamine and methamphetamine in municipal wastewater influent and effluent using weak cation‐exchange SPE and LC‐MS/MS

Amphetamine and methamphetamine are emerging contaminants—those for which no regulations currently require monitoring or public reporting of their presence in our water supply. In this research, a protocol for weak cation‐exchange (WCX) SPE coupled with LC‐MS/MS was developed for determination of emerging contaminants amphetamine and methamphetamine in a complex wastewater matrix. Gradient LC parameters were adjusted to yield baseline separation of methamphetamine from other contaminants. Methamphetamine‐D5 was used as the internal standard (IS) to compensate for sample loss during SPE and for signal loss during MS (matrix effects). Recoveries were 102.1 ± 7.9% and 99.4 ± 4.0% for amphetamine and methamphetamine, respectively, using WCX sorbent. Notably, methamphetamine was determined to be present in wastewater influent at each sampling date tested. Amphetamine was present in wastewater influent on two of four sampling dates. Amphetamine concentrations ranged from undetectable to 86.4 ng/L in influent, but it was undetectable in wastewater effluent. Methamphetamine was detected in influent at concentrations ranging from 27.0–60.3 ng/L. Methamphetamine concentration was reduced but incompletely removed at this facility. Although absent in one post‐UV effluent sample, concentrations of methamphetamine ranged from 10.8–14.8 ng/L.     

基于ARIMA模型的我国大宗农产品价格指数预测

以2006年6月至2015年12月我国大宗农产品价格指数月度时间序列作为研究对象.构建ARIMA(1,1,1)模型对我国大宗农产品价格指数进行了拟合和预测,并对模型拟合效果和预测准确度进行了检验,效果均良好.预测结果表明,从长期变化趋势看,我国大宗农产品价格指数上涨是大势所趋.从短期变化趋势看,大宗农产品面对较大的价格下行压力.     

Pentannulation of Heterocycles by Virtue of Precious Metal Catalysis

Pentannulated heterocycles are the key structural subunit of many natural and biologically active compounds. Over the last decades, many precious metal‐assisted pentannulations have been described as a consequence of an extensive research. This Focus Review gives an overview of precious metal‐catalyzed reactions applied to the synthesis of cyclopenta‐fused heterocycles in the last five years.     

同位素稀释高效液相色谱-串联质谱法测定水果及其制品中的展青霉素

建立了同位素稀释高效液相色谱-串联质谱法对水果及其制品中的展青霉素进行测定。澄清果汁(浊汁、固液体及固体样品需用果胶酶酶解处理,乙酸乙酯提取浓缩后复溶)经混合型阴离子交换柱净化、富集后,采用Waters HSS T3柱(2.1 mm×100 mm,1.8μm)以乙腈-水为流动相梯度洗脱,电喷雾离子源离子化,负离子多反应离子监测(MRM)模式检测,同位素稀释内标法定量。展青霉素在5~250 ng/m L浓度范围内线性关系良好,相关系数(r~2)大于0.999,该方法在不同基质不同加标浓度下,回收率为90.6%~110.1%,相对标准偏差(RSD)为1.4%~3.9%,定量下限为5.0μg/kg(苹果汁中定量下限为2.0μg/kg)。该方法准确可靠、灵敏度高,适合于水果及其制品中展青霉素的测定,可满足我国GB 2761-2011对于水果制品、果蔬汁和酒类(仅限苹果和山楂)中展青霉素残留的检测要求。     

烟草制品及烟气中重金属检测方法的研究进展

从烟草制品及其烟气的前处理方法和检测方法两方面对烟草中重金属含量测定的研究进展进行了综述。重点介绍了湿法消解、微波消解、萃取和悬浮进样技术等样品前处理方法,以及原子光谱法、质谱法和液相色谱法等测定方法。列举了不同方法的灵敏度、准确性和适用范围,对各方法的优缺点进行了比较,并对烟草中重金属检测方法的发展进行了展望。     

Nano/Biomimetic Tissue Adhesives Development: From Research to Clinical Application

Wound closure and healing have been a problem that humans have faced since the ancient eras. An appropriate tissue connector must hold the edges of injured tissues close together to support healing and also prevent the leakage of biological fluids when resisting against the tensile forces. Even though clinical usage of mechanical methods is convenient for wound closure, their application has some limitations and drawbacks such as being painful for patients and hard to apply for surgeons when the injured site is not in touch. Furthermore, they do not have desirable cosmetic results. To solve these problems, closing the wounds with sticky materials has been introduced to prevent bleeding and induce the wound healing process. To this regard, many types of surgical adhesives including tissue adhesives have been developed to be a suitable alternative for sutures and staples. There is also a new approach which aims at producing bioadhesives by mimicking the nature along with applying nanotechnology methods. Today, many studies have been done to develop new adhesives inspired by nature. We have attempted to introduce the fundamentals of wound healing along with the different types of bioadhesives, their properties, and clinical applications in a simple and illustrated comprehensive way.     

Biomimetic Total Synthesis of Hyperjapones A–E and Hyperjaponols A and C

Hyperjapones A–E and hyperjaponols A–C are complex natural products of mixed aromatic polyketide and terpene biosynthetic origin that have recently been isolated from Hypericum japonicum. We have synthesized hyperjapones A–E using a biomimetic, oxidative hetero‐Diels–Alder reaction to couple together dearomatized acylphloroglucinol and cyclic terpene natural products. Hyperjapone A is proposed to be the biosynthetic precursor of hyperjaponol C through a sequence of: 1) epoxidation; 2) acid‐catalyzed epoxide ring‐opening; and 3) a concerted, asynchronous alkene cyclization and 1,2‐alkyl shift of a tertiary carbocation. Chemical mimicry of this proposed biosynthetic sequence allowed a concise total synthesis of hyperjaponol C to be completed in which six carbon–carbon bonds, six stereocenters, and three rings were constructed in just four steps.     

Copper(I)‐Catalyzed Asymmetric Dearomatization of Indole Acetamides with 3‐Indolylphenyliodonium Salts

The rapid and direct asymmetric synthesis of 3‐(3a‐indolyl)hexahydropyrroloindoline motifs is an extremely important part of the total synthesis of several alkaloid structures. Herein, an intermolecular, asymmetric cascade dearomatization reaction of indole acetamides with 3‐indolylphenyliodonium salts has been developed. This protocol provides a straightforward access to 3‐(3a‐indolyl)hexahydropyrroloindolines bearing an all‐carbon quaternary stereocenter at the C3 position of the indoline ring with high enantioselectivities. The utility of the protocol has been demonstrated by the formal asymmetric synthesis of folicanthine.     

稳定同位素标记D_4-罗丹明B的合成及表征

以全氘代邻二甲苯为同位素标记前体,经氧化得到的D_4-邻苯二甲酸与3-羟基-N,N-二乙基苯胺反应生成稳定同位素标记的D_4-罗丹明B,总收率36.9%。目标产物的结构经质谱(MS)、核磁(NMR)等技术手段表征确认,通过高效液相色谱确定化学纯度高于98.0%,同位素氘丰度大于98.0%。将其作为同位素内标试剂用于果汁中罗丹明B的残留检测,在0.05~50 mg/L范围内呈良好的线性关系,其检出限为5μg/kg,回收率为96.4%~103.4%,相对标准偏差(RSD)为1.0%~1.2%,具有很高的灵敏度和准确性。为食品安全领域违禁色素的检测提供了一种可靠实用的方法。