气相色谱-正化学源质谱法测定家用橡胶手套中7种N-亚硝胺及其前体物的迁移量

该文用Sep-Pak AC2串联Sep-Pak Dry cartridges固相萃取小柱对家用橡胶手套迁移提取液中的N-亚硝基二甲胺(NDMA)、N-亚硝基二乙胺(NDEA)、N-亚硝基二丙胺(NDPA)、N-亚硝基二丁胺(NDBA)、N-亚硝吗啉(NMOR)、N-亚硝基吡咯烷(NPYR)和N-亚硝基哌啶(NPIP)7...     

乳胶制品中N-亚硝胺析出物的GC-MS/SIM检测

使用气相色谱-质谱(GC-MS/SIM)检测了乳胶制品中5种N-亚硝胺析出物,样品经过二氯甲烷萃取,用Rtx-5MS石英毛细管柱分离,采用内标法进行检测计算.实验得出5种N-亚硝基化合物的内标标准曲线日内RSD(小于5%),日间RSD(小于14%).N-亚硝基二乙胺(NDEA)、N-亚硝基二丙胺(NDPA)、N-亚硝基哌啶(NPIP)、N-亚硝基二丁胺(NDBA)、N-亚硝基二苯胺(NDPhA)的方法的检出限分别为2.0,5.0,10.0,1.0,112.0μg/L.运用该法对北京市场的乳胶制品进行了检测.     

气相色谱-三重四极杆质谱联用法检测市售腊肠中9种挥发性亚硝胺

采用QuEChERS方法对市售腊肠中的N-亚硝基二甲胺(NDMA)、N-亚硝基二乙胺(NDEA)、N-亚硝基甲乙胺(NMEA)、N-亚硝基二丙胺(NDPA)、N-亚硝基吡咯烷(NPYR)、N-亚硝基哌啶烷(NPIP)、N-亚硝基二丁胺(NDBA)、N-亚硝基吗啉(NMOR)、N-亚硝基二苯胺(NDPhA)9种对人体有致癌活性的挥发性亚硝胺进行分离净化,气相色谱-三重四极杆质谱联用法(GC-MS/MS)检测。最佳实验条件下,9种挥发性亚硝胺的线性范围为0.25~200μg/L,检出限为0.01~0.10μg/kg,加标回收率为90.7%~116.0%,相对标准偏差(RSD)为1.8%~14.0%。市售腊肠样品中NDMA,NMOR,NPYR,NDPA,NPIP,NDBA,NDPhA均有不同程度的检出,总挥发性亚硝胺的含量为1.85~13.44μg/kg。该方法灵敏度高、操作简单,适合批量样品的快速检测。     

N,N-二乙基胺乙基取代瓜尔胶的合成及结构表征

在碱催化条件下,利用N,N-二乙基氯乙胺盐酸盐与瓜尔胶和羟丙基瓜尔胶一步法合成得到N,N-二乙基胺乙基瓜尔胶和N,N-二乙基胺乙基羟丙基瓜尔胶。结果显示合成过程中温度、反应时间、羟丙基取代度及溶剂等因素对产品分子量和N,N-二乙基胺乙基取代度有影响。通过红外光谱和核磁法对N,N-二乙基胺乙基瓜尔胶和羟丙基N,N-二乙基胺乙基瓜尔胶的分子结构进行了分析,并通过碳谱对N,N-二乙基胺乙基在瓜尔胶分子链中糖环上的取代分布进行了分析。     

1H-苯并三唑及其衍生物的光化学合成

邻苯二胺及其衍生物与N-亚硝基二苯胺在氩气保护、光照条件下,以二氯甲烷为溶剂,发生从N-亚硝基二苯胺到邻苯二胺的亚硝基转移反应,反应最终生成1H-苯并三唑及其衍生物.N-亚硝基二苯胺与N,N'-二甲基邻苯二胺也可以发生亚硝基转移反应,生成N,N'-二甲基-N-亚硝基邻苯二胺,不能环化生成1H-苯并三唑类产物.N-亚硝基...     

芳胺汞化合物的合成及其分子内重排缩合反应

利用简便易得的N-取代苄基芳胺的汞化产物,经亚硝化反应得到8种N-取代苄基-N-亚硝基-2-乙酸汞基芳胺,并通过分子内缩合合成了一种苯并咪唑衍生物,其结构经元素分析、1HNMR、IR及X射线单晶衍射确证。此方法为合成咪唑类化合物提供了一条新途径。     

丹酰氯柱前衍生高效液相色谱测定痕量脂肪族仲胺

脂肪族仲胺在适宜条件下很容易形成强致癌物N-亚硝基化合物,因此研究N-亚硝基化合物及其前身物脂肪族仲胺的灵敏和准确的测定方法是研究癌变过程及其机理的前提条件。 丹酰氯作为荧光衍生试剂已广泛应用于氨基酸、生物胺和多胺的高效液相色谱分析,但应用于测定脂肪族仲胺尚未见报     

水蒸气蒸馏-活性炭柱固相萃取/GC-MS/MS法测定火腿中8种N-亚硝胺

建立了水蒸气蒸馏提取,活性炭柱固相萃取,气相色谱-串联质谱(GCM S/M S)检测火腿中8种N-亚硝胺的新方法。样品经水蒸气蒸馏提取,馏出液经Sep-Pak AC-2活性炭柱固相萃取进行净化与富集,二氯甲烷洗脱,以多重反应监测(MRM)方式进行GC-MS/MS检测。在考察的浓度范围内(1~400 ng/m L)方法线性良好,R20.9995,除N-二甲基亚硝胺(NDM A)和N-亚硝基甲乙胺(NMEA)检出限≤0.1 ng/g外,其它分析物的检出限为≤0.04 ng/g;在0.3,3和10μg/kg 3个水平的添加回收率为78.7%~118.2%,除N-亚硝基吗啉(NM OR)回收率略低,为45.2%~58.2%,相对标准偏差为2.5%~21%。应用该方法对市售的4种火腿进行检测,结果表明NDMA和N-亚硝基吡咯烷(NPYR)是主要的挥发性N-亚硝胺,含量分别为0.30 ng/g和0.56~0.99 ng/g,N-二乙基亚硝胺(NDEA)、NMOR和N-二丁基亚硝胺(NDBA)均有检出,但含量低于定量限,NM EA、N-二丙基亚硝胺(NDPA)和N-亚硝基哌啶(NPIP)未检出。     

欧盟EN12868方法与固相微萃取-气质联用法检测乳胶气球中亚硝胺模拟迁移量

利用欧盟EN12868方法对市售乳胶气球中的8种挥发性亚硝胺及其前体物的模拟迁移量进行了检测,包括N-亚硝基二甲胺(NDMA),N-亚硝基二乙胺(NDEA),N-亚硝基二丙胺(NDPA),N-亚硝基异丙胺(NDiPA),N-亚硝基二丁胺(NDBA),N-亚硝基哌啶(NPIP),N-亚硝基吡咯烷(NPYR),N-亚硝基吗啉(NMOR)。其中NDMA,NDEA和NDBA 3种亚硝胺及其前体物被检出,且均超标。建立了顶空-固相微萃取-气相色谱-质谱法(HS-SPMEGC-MS)快速测定乳胶气球中亚硝胺模拟迁移量的分析方法。样品置于人工唾液40℃浸提1h来模拟气球的使用情况,考察了不同的萃取条件对分离检测的影响,综合评价了4种检测系统的性能。8种亚硝胺的方法检出限为0.26~5.38μg/kg。利用所建方法检测9种市售乳胶气球中亚硝胺的模拟迁移总量为31.37~337.72μg/kg。     

异亚硝基乙酰乙酸乙酯亚胺Pd(Ⅱ)配合物的合成、表征和tran Pd(p-CH3C6H4-IEAI)2的晶体结构

二齿异亚硝基-β-酮胺配体,由于异亚硝基(肟基)配位功能引起人们的兴趣.在已知的这类配体的金属配合物中,肟基可通过N原子或/和O原子与金属原子配位形成各种键合异构体[1-4].     

Environmentally Friendly Techniques and Their Comparison in the Extraction of Natural Antioxidants from Green Tea,Rosemary, Clove,and Oregano

Many current food and health trends demand the use of more ecological, sustainable, and environmentally friendly techniques for the extraction of bioactive compounds, including antioxidants. However, extraction yields and final antioxidant activities vary between sources and are highly influenced by the given extraction method and nature and ratio of the employed solvent, especially for total polyphenols, flavonoids, and anthocyanins, which are well recognized as natural antioxidants with food applications. This review focused on the most common extraction techniques and potential antioxidant activity in the food industry for various natural antioxidant sources, such as green tea, rosemary, clove, and oregano. Green extraction techniques have been proven to be far more efficient, environmentally friendly, and economical. In general, these techniques include the use of microwaves, ultrasound, high hydrostatic pressure, pulsed electric fields, enzymes, and deep eutectic solvents, among others. These extraction methods are described here, including their advantages, disadvantages, and applications.     

Green synthesis of biogenic metal nanoparticles by terrestrial and aquatic phototrophic and heterotrophic eukaryotes and biocompatible agents

The size, shape and controlled dispersity of nanoparticles play a vital role in determining the physical, chemical, optical and electronic properties attributing its applications in environmental, biotechnological and biomedical fields. Various physical and chemical processes have been exploited in the synthesis of several inorganic metal nanoparticles by wet and dry approaches viz., ultraviolet irradiation, aerosol technologies, lithography, laser ablation, ultrasonic fields, and photochemical reduction techniques. However, these methodologies remain expensive and involve the use of hazardous chemicals. Therefore, there is a growing concern for the development of alternative environment friendly and sustainable methods. Increasing awareness towards green chemistry and biological processes has led to a necessity to develop simple, cost-effective and eco-friendly procedures. Phototrophic eukaryotes such as plants, algae, and diatoms and heterotrophic human cell lines and some biocompatible agents have been reported to synthesize greener nanoparticles like cobalt, copper, silver, gold, bimetallic alloys, silica, palladium, platinum, iridium, magnetite and quantum dots. Owing to the diversity and sustainability, the use of phototrophic and heterotrophic eukaryotes and biocompatible agents for the synthesis of nanomaterials is yet to be fully explored. This review describes the recent advancements in the green synthesis and applications of metal nanoparticles by plants, aquatic autotrophs, human cell lines, biocompatible agents and biomolecules.     

Synthesis,structure, and function of internally functionalized dendrimers

The past three decades have witnessed an exponential increase in the structural diversity and applications of dendrimers, spanning across drug delivery and diagnostics, protein, and enzyme mimicry, solubility enhancement, coatings, light harvesting, and catalysis. The dendrimer community has recently focused on internally functionalized dendrimers (IFDs) owing to their advanced design and functionality. The synthesis of IFDs relies on advanced orthogonal chemistries and/or (de)protection schemes, as well as careful purification to minimize polydispersity of composition and molecular weight. The studies published on IFDs, however, lay scattered across the chemical literature, and a comprehensive presentation of structural rationale, synthetic procedures, and technologically relevant applications is missing. To address this need, this review presents a comprehensive collection and discussion of all available studies on IFDs, detailing their methods of synthesis and their structure–function correlations. The wide variety of internal functionalities, including hydroxyl, amine, carboxylic acid, allyl, alkyne, and imidazole groups, enables myriad applications in biochemistry, chemical and biomedical engineering, and material science. Particular focus is given to IFDs that are amenable to modular synthetic strategies, which promote higher synthetic yield and scalability, and therefore possess stronger translational and commercial potential. As such, this review guides research groups pursuing the difficult task of IFD rational design and synthesis providing them a concise roadmap to their mission.     

Recent development in nanomaterials fabricated paper-based colorimetric and fluorescent sensors: A review

The paper-based sensing devices have drawn a broad interest in analytical chemistry for colorimetric and fluorescent-based analysis of biological, environmental, clinical, and food samples. It is due to the simple, rapid, biodegradable, user-friendly, less expensive, and low waste generation into the environment. Here, the recent development of paper-based sensors fabricated with different noble metal nanoparticles (NPs) and semiconductor and carbon quantum dots (QDs) is demonstrated to analyze several chemical substances from various samples. User-friendly and portable recording devices such as digital cameras, smartphones, scanners, etc. along with color detecting softwares are employed to measure the color intensity of nanomaterials fabricated paper devices after the deposition of a sample solution containing various chemical substances. The advantages and disadvantages of incorporating nanomaterials in the paper substrate (direct deposition, inkjet printing, screen printing and wax printing) are illustrated. The mechanism for colorimetric, fluorescence, phosphorescence, and chemiluminescence sensing using noble metal NPs (Ag, Cu, and Au), semiconductors, and carbon QDs for the determination of metal ions, anions, pesticides, biomolecules, and other toxic chemical substances are discussed. Thus, this review article would be highly useful for scientists and researchers to design colorimetric sensors to monitor chemical toxicants in clinical, environment, foods, and many other related samples.     

生物光化学

生物光化学研究光在动植物体内所引起的生化现象。例如:经过各种不同波长的光辐照后的生命现象,生长规律,某些生理和病理过程,疾病的产生和治疗机理,细胞的辐射损伤和自然防御,以及光合色素在生物进化中的作用等。本文就光引起的现象:视觉、生物钟(光周期性)、植物的光合作用、辐射损伤及其修复、牛皮癣的治疗、新生儿黄疸病的治疗机理,以及光合色素——藻胆蛋白等七种现象,做了综述性的介绍。     

三唑类药物研究新进展

三唑类化合物作为药物广泛应用于临床,是目前药物研究开发的重点领域之一．越来越多的高活性、低毒性、不良反应少、多药耐药性小、生物利用率高、药代动力学性质好、药物靶向性强、给药方式多样化、广谱、高疗效的三唑类化合物作为候选药物或药物用于临床医治多种疾病,显示出了三唑类化合物在医药领域的巨大开发价值和潜在的宽广应用．本文结合自己的工作,参考国内外近五年文献系统地综述了三唑类化合物作为药物在整个医药领域的研究与开发近况,包括抗真菌、抗细菌、抗结核、抗癌、抗病毒、抗炎镇痛、抗惊厥等,并展望其发展趋势与前景．希望该评论有助于为高活性低毒性三唑类医药合理设计提供新思路．     

Cover Picture: Nanomaterials for Fluorescence and Multimodal Bioimaging (Chem. Rec. 3/2023)

Bioconjugated nanomaterials replace molecular probes in bioanalysis and bioimaging in vitro and in vivo. Nanoparticles of silica, metals, semiconductors, polymers, and supramolecular systems, conjugated with contrast agents and drugs for image-guided (MRI, fluorescence, PET, Raman, SPECT, photodynamic, photothermal, and photoacoustic) therapy infiltrate into preclinical and clinical settings. Small bioactive molecules like peptides, proteins, or DNA conjugated to the surfaces of drugs or probes help us to interface them with cells and tissues. Nevertheless, the toxicity and pharmacokinetics of nanodrugs, nanoprobes, and their components become the clinical barriers, underscoring the significance of developing biocompatible next-generation drugs and contrast agents. This account provides state-of-the-art advancements in the preparation and biological applications of bioconjugated nanomaterials and their molecular, cell, and in vivo applications. It focuses on the preparation, bioimaging, and bioanalytical applications of monomodal and multimodal nanoprobes composed of quantum dots, quantum clusters, iron oxide nanoparticles, and a few rare earth metal ion complexes.     

THE EFFECT OF CLAY DISPERSION ON THE CRYSTALLIZATION AND MORPHOLOGY OF POLYPROPYLENE／CLAY COMPOSITES

PP/clay composites with different dispersions, namely, exfoliated dispersion, intercalated dispersion and agglomerates and particle-like dispersion, were prepared by direct melt intercalation or compounding. The effect of clay dispersion on the crystallization and morphology of PP was investigated via PLM, SAXS and DSC. Experimental results show that exfoliated clay layers are much more efficient than intercalated clay and agglomerates of clay in serving as nucleation agent due to the nano-scale dispersion of clay, resulting in a dramatic decrease in crystal size (lamellar thickness and spherulites) and an increase of crystallization temperature and crystallization rate. On the other hand, a decrease of melting temperature and crystallinity was also observed in PP/clay composites with exfoliated dispersion, due to the strong interaction between PP and clay. Compared with exfoliated clay layers, the intercalated clay layers have a less important effect on the crystallization and crystal morphology. No effect is seen for samples with agglomerates and particle-like dispersion, in regard to melting temperature, crystallization temperature, crystal thickness and crystallinity.     

Purification and properties of three cellobiases from Aspergillus niger A20

Three cellobiases, here called cellobiase A, B, and C, from the culture filtrate of Aspergillus niger A20, were purified by precipitation with ammonium sulphate, gel filtration through Sephadex G-75, and column chromatography of DEAE-cellulose. The purified enzymes were homogeneous on polyacrylamide disk electrophoresis. The mol wt of the purified enzymes were estimated by SDS-gelelectrophoresis to be 88,000, 80,000, and 71,000 for cellobiases A, B, and C, respectively. The enzymes were active at pH 4.5 and 55–60°C. The pattern of their aminoacid compositions showed high contents of aspartic acid, glutamic acid, threonine, serine, and glycine. The apparent K_m values for cellobiose were 0.9, 1.63, and 1.0 mM for cellobiases A, B, and C, respectively. Calcium ions stimulated cellobiases B and C, and Co²⁺ and Mg²⁺ ions stimulated cell obiase A. The purified enzymes hydrolyzed cellobiose and aryl-β-d-glucosides, but they had no action on sucrose, maltose, and cellulose. The three cellobiases catalyzed transglycosylate reaction, and the major product formed from cellobiose was tetramer of glucose.     

石墨烯纤维：制备、性能与应用

石墨烯纤维是一种由石墨烯片层紧密有序排列而成的一维宏观组装材料。通过合理的结构设计和可控制备,石墨烯纤维能够将石墨烯在微观尺度的优异性能有效传递至宏观尺度,展现出优异的力学、电学、热学等性能,从而应用于功能织物、传感、能源等领域。目前,石墨烯纤维主要通过湿法纺丝、限域水热组装等方法制备得到,其性能可以通过对材料体系和制备工艺的优化而进一步提升。本文首先介绍了石墨烯纤维的制备方法,然后详细阐述了石墨烯纤维的性能,讨论了其性能提升策略,并总结了石墨烯纤维的应用,最后对石墨烯纤维的未来发展、挑战和前景进行了展望。