顶空-气相色谱-质谱法测定食品接触ABS,AS制品中丙烯腈

建立了测定食品接触ABS,AS制品中丙烯腈含量的顶空-气相色谱-质谱法。样品经N,N-二甲基乙酰胺(DMA)溶解,置于自动顶空进样仪中加热并达到平衡后,取顶空气体进气相色谱-质谱仪分析。本方法采用弱极性的HP-5 ms(30 m×0.25 mm(内径)×0.25μm(膜厚))毛细管色谱柱对丙烯腈与杂质进行色谱分离,特别是对食品接触ABS制品消除了4-乙烯基-1-环己烯对丙烯腈测定的干扰,并以质谱检测器的选择离子监测模式(SIM)进行定性、定量分析。结果表明,丙烯腈质量浓度在0.2~50.0 mg/L范围内,线性方程为y=2782.2127ρ+295.0920,相关系数为r=0.9995;方法检出限为0.6 mg/kg;平均回收率为94.5%~101.1%;相对标准偏差(n=6)为1.6%~2.4%。是测定食品接触ABS,AS制品中丙烯腈单体含量的有效方法。     

气相色谱–质谱联用法测定空气中的丙烯腈

建立测定空气中丙烯腈的气相色谱–质谱联用方法。用活性炭管采集样品,以体积分数为2%的丙酮二硫化碳溶液解吸,利用气相色谱–质谱法以选择离子扫描方式采集数据并进行分析,以色谱峰面积外标法定量。丙烯腈的质量浓度在0~100μg/m L范围内与色谱峰面积线性关系良好,线性相关系数(r~2)为0.999 0。丙烯腈检出限为1.2μg/m L,最低检出质量浓度为0.16 mg/m~3(以采样体积7.5 L计),平均加标回收率为97.0%~99.3%,测定结果的相对标准偏差为3.0%~4.2%(n=6)。该方法定性、定量准确,精密度、灵敏度高,可用于空气中丙烯腈的常规检测。     

丙烯腈微生物转化产物的反相高效液相色谱分析

丙烯腈(Acrylonitrile,简称AN)及其微生物转化产物丙烯酰胺(Acrylamide,简称AM)和丙烯酸(Acrylic Acid,简称AA)的混合样品,通常采用气相色谱法(GC)分析。GC法要求分析系统保持恒定高温,且需将水样进行特殊的预处理。用HPLC分析此类化合物,国内尚未见报道。我们用高效液相色谱法(HPLC)在常温下对丙烯腈及其微生物转化产物直接进行了分离分析,重现性好,周期短,适用于批量样品的连续测定。     

固相萃取膜技术用于自来水中丙烯酰胺的测定

开发了一种简便快速的固相萃取膜(SPE disk)技术,实现了对500 mL自来水中微量丙烯酰胺的富集,采用高效液相色谱法(HPLC)完成其定性和定量测定。比较不同填料的吸附情况,选择活性炭作为丙烯酰胺的最佳吸附剂。考察了洗脱剂种类、洗脱剂体积、洗脱速率和穿透体积等条件对萃取结果的影响,优化了色谱分离条件。经膜萃取过的丙烯酰胺在0.05～0.5 mg/L质量浓度范围内,其峰面积与质量浓度的线性关系良好,相关系数为0.998,检出限为20 ng/L。该方法对不同体积、不同浓度的丙烯酰胺溶液的回收率为94.12%～100.2%,相对标准偏差为2.09%～4.51%(n=3),自来水样品的加标回收率为79.96%。该方法操作简单、快速、灵敏度高,适合对水样中丙烯酰胺的测定。     

计算机快速富里叶变换应用于气相色谱痕量分析

将计算机快速富里叶变换(FFT)应用于高分辨率气相色谱痕量分析中，以增加色谱峰的S／N比(信号与噪声比)，提高分析精度，对S／N非常低的色谱峰采用的这种计算机快速富里叶变换平滑新方法，可以提取出几乎被噪声淹没的色谱信号，使S／N比提高12倍以上，而色谱峰面积误差非常小。     

二阶梯度升温热解吸法测定空气中的微量丙烯腈和乙腈

采用气体采样泵将空气样品的丙烯腈和乙腈吸附到吸附管中,用二阶梯度升温将吸附管中的被测物质解吸到冷阱中,再快速对冷阱升温,将冷阱中的被测物质解吸进入色谱柱进行分离,用气相色谱氢火焰检测器检测空气中的微量丙烯腈和乙腈。丙烯腈、乙腈的色谱峰面积与吸附质量的线性相关系数均大于0.995。该法对实际空气样品中丙烯腈的检出限为5μg/m3,乙腈的检出限为10μg/m3,加标回收率均大于90%。     

水稻干胚膜脂的气相色谱分析

薄层色谱-气液色谱(TLC-GLC)法用于植物类脂及其脂肪酸的分析,不但费时,而且误差较大。近年来多采用气相色谱分析法,但关于水稻干胚膜脂的测定未见详细报道。本文用气相色谱法分析测定了水稻干胚膜脂的相对含量,简便、快速、准确。     

新型固相微萃取膜及其在分析沙土中梯恩梯的应用

本文用酰胺类化舍物和气相色谱固定液制备了一种新型固相微萃取膜，应用该类固相微萃取膜成功地分离了沙土中炸药梯恩梯，并利用气相色谱／质谱联用技术对分离后的样品进行了分析。     

移动床热煤气脱硫气固反应过程模拟：Ⅱ.错流移动床非催化气固反 …

基于前文错流移动床反应器模型方程,模拟计算并分析了该类反应器中气、固相流动对热煤气脱硫等非催化气固反应过程的影响。研究表明,床层在床深方向按反应速率的快慢可分为粗脱区和精脱区,在颗粒流动方向上气相浓度差异较大,并主要体现在粗脱区内,床层出口处颗粒转化呈现较大分布,反应器内气因交错流动,气相浓度的颗粒转化率共同作用（于气固反应速率）等因素是造成过程特征的主要因素。因此反应器优化应满足对两相流动的优化     

简便、灵活、双气路气相色谱微型反应器

反应气体色谱是一种化学反应和气相色谱相结合的技术,在许多气相色谱专著中都有论述。它能提供官能团的信息,补充光谱和其他结构分析的数据;做色-质分析时,可通过反应色谱消除某些官能团化合物的干扰,使分析更加准确。反应色谱也可用于催化剂的研究。色谱反应器,根据实验时安放的位置大致可分为三类:(一)与分析柱相连接的减除环,或直接用分析柱本身的前后几厘米作为反应器;(二)用汽化室作反应器;(三)预柱反应器,即在色谱系统之前另加一反应器。但是这些反应器不能很好地调温,不能同时得到反应谱图和参比谱图,有气阻差,它们的反应床与整个反应器是一整体,     

Acrylamide production in an ultrafiltration-membrane bioreactor using cells of Brevibacterium imperialis CBS 489-74

Both differential and integral UF-membrane reactors were tested for the bioconversion of acrylonitrile into acrylamide. Use was made of the commercially available flat membrane cell Amicon Mod.52 and the UF-membranes FS81PP, GR81PP, and YM100. The enzymatic reaction was catalyzed by the nitrile hydratase (NHase) present in resting cells of Brevibacterium imperialis CBS 489-74. The system was operated at 4°C and 10°C. Acrylonitrile concentration ranged from 50 to 500 mM. The membrane resistance to chemicals was complete at acrylonitrile and acrylamide concentrations up to 800 mM and 2 M, respectively. No rejection of solute was determined. Membranes totally retained the resting cells and no fouling was observed working with 2 and 16 mg of biocatalyst in stirred systems. Membrane compaction was apparently responsible for roughly 35% flux loss during the first 3–4 h of operation. The laboratory scale membrane bioreactor, continuously operating, allowed to show the dependence of enzyme deactivation on acrylonitrile concentration and process time. Substrate concentration higher than 100 mM were highly detrimental for NHase stability. The acrylamide yield reached in the multi-cycle process operating with 5.6 g/l of resting cells was 93.7% and the product concentration during roughly 450 h of bioconversion attained 8.3% (w/v). Decay of specific membrane flux was 98% of the initial value.     

紫外光谱法实时测定腈水合酶的催化动力学

采用紫外光谱法研究了腈水合酶催化丙烯腈水合的过程,在不同丙烯腈初始浓度下,测定了催化过程中275nm紫外吸光度的变化,计算出丙烯酰胺的生成速率.用Michaelis-Menten方程对不同丙烯腈浓度下的Nocardiasp.腈水合酶催化速率进行了拟合,得到该酶以丙烯腈为底物的米氏常数(K_m)为8.46mmol/L,单位质量腈水合酶的催化速率常数(k_cat)为2398μmol/(min·mg).     

芳香族重氮盐氧化还原引发体系的研究——Ⅳ.利用4,4′-联苯双重氮硼氟酸盐进行嵌段共聚

提供了一种利用芳族双重氮盐进行嵌段共聚的新方法。研究了利用4,4′-联苯双重氮硼氟酸盐与亚铁盐引发丙烯腈低温沉淀聚合,使聚合物末端带上重氮基与包藏自由基,然后与甲基丙烯酸或丙烯酰胺进行嵌段共聚,所得嵌段共聚物为BAB型。研究了4,4′-联苯双重氮硼氟酸盐与亚铁盐引发丙烯酰胺水溶液聚合,使聚合物末端带有重氮基,再与丙烯腈或丙烯酸甲酯嵌段共聚。     

4-(1,2-亚乙二氧基)环己酮及其2-甲醛和2-羧酸酯的烯胺和烯醇反应的研究

4-(1,2-亚乙二氧基)环己酮及其2-甲醛和2-羧酸酯的烯胺和烯醇与丙烯酸型的和丙二酸型的试剂反应,获得了与6-(1,2-亚乙二氧基)-5,6,7,8-四氢-2(1H)- 喹啉酮很相近的四个化合物(5,11,18,19)和六个其它化合物(4,7,8,9,16,17).探讨了这十个均未见于文献的新化合物的生成机理,并得到一个制备5- 四氢萘胺衍生物的新方法     

Influence des solvants sur la copolymérisation de l'acrylamide avec l'acrylonitrile

The copolymerization of acrylamide with acrylonitrile was investigated in various solvents, which can be put into three groups according to their influence on molecular associations; (1) solvents autoassociated by hydrogen- bonds (acetic acid, methanol, water, dimethylformamide); (2) polar solvents which can associate with the NH group of acrylamide (acetonitrile, dioxane, acetone); (3) inert solvents (toluene, benzene, hexane). The reaction kinetics and the compositions of the copolymers are different for each group of solvents. The composition of copolymers formed in solvents of group 1 vary widely, depend- ing on the solvent. Copolymers formed in all solvents of group 2 have the same composition which is that of copolymers formed in bulk. The amount of acrylamide is highest in copolymers formed in inert solvents of group 3. Such parameters as the degree of conversion, the reaction temperature, the mode of initiation and the extent of dilution only slightly affect the composition of copolymers. Homopolymerizations of acrylamide and acrylonitrile were investigated in all solvent used.The results suggest that the effects of solvents on the copolymerization of acrylamide with acrylonitrile are consequences of the various modes of molecular association of acrylamide. The solvents affect the equilibrium between auto- association of acrylamide and its association with solvent and thereby affect the reactivity of the monomer.     

A new approach based on off‐line coupling of high‐performance liquid chromatography with gas chromatography‐mass spectrometry to determine acrylamide in coffee brew

A new method based on off‐line coupling of LC with GC in replacement of conventional sample preparation techniques is proposed to analyze acrylamide in coffee brews. The method involves the preseparation of the sample by LC, the collection of the selected fraction, its concentration under nitrogen, and subsequent analysis by GC coupled with MS. The composition of the LC mobile phase and the flow rate were studied to select those conditions that allowed separation of acrylamide without coeluting compounds. Under the conditions selected recoveries close to 100% were achieved while LODs and LOQs equal to 5 and 10 μg/L for acrylamide in brewed coffee were obtained. The method developed enabled the reliable detection of acrylamide in spiked coffee beverage samples without further clean‐up steps or sample manipulation.     

Functionalization of polyisobutylene and polyisobutylene oligomers via the ritter reaction

The Ritter reaction, that is, reaction of a carbocation with a nitrile, was carried out on polyisobutylene (PIB) using a variety of reaction conditions. End quenching of PIB carbocations with acrylonitrile under living polymerization conditions (methyl chloride (MeCl)/hexane 60/40 (v/v) solvent mixtures at −70 °C) resulted in either tert‐chloride end groups or loss of chain‐end fidelity via carbocation rearrangement, as evidenced by NMR spectroscopy. Exo‐olefin functionalized PIB substrates were also reacted with nitriles under a variety of reaction conditions including various acid and solvent medium combinations. In all cases, the result was either no reaction or PIB that had undergone severe backbone degradation, as determined via NMR spectroscopy and gel permeation chromatography. Finally, the Ritter reaction was performed on a series of exo‐olefin functionalized oligoisobutylenes using acrylonitrile as the nitrile and either 60/40 dichloromethane/hexane or excess acrylonitrile as the solvent. In 60/40 dichloromethane/hexane, significant carbocation rearrangement and/or degradation resulted in a variety of isomeric, acrylamide‐functionalized oligomers. In excess acrylonitrile, the desired Ritter reaction was the only reaction observed, resulting in the smooth formation of the terminal acrylamide. The various N‐oligoisobutylacrylamides thus obtained represent new hydrophobic monomers useful for the introduction of hydrophobic moieties into acrylamide‐based water‐soluble polymers. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 840–852     

Chromatographic determination of residual monomers in starch-g-polyacrylonitrile and starch-g-polyacrylate

Summary A reverse-phase HPLC method for simultaneous determination of acrylonitrile (AN), acrylamide (AM) and acrylic acid (AC) was developed. The residual monomer AC was quantified in several industrial polymers as well as grafted copolymers. Products of biodegradation of these copolymers were also identified.     

Polymerization of Acrylamide and Copolymerization with Acrylonitrile with AIEt3-Hexamethyl Phosphoric Acid Triamide Complex

The polymerization of acrylamide and its copolymerization with acrylonitrile were investigated with AIEt₃ and AIET₃-hexamethyl phosphoric acid triamide. AIEt₃ initiates the polymerization of acrylamide. The addition of hexamethyl phosphoric acid triamide greatly influences the yields of methanol-insoluble polymer, η_sp/c, and the structure of polymer. Vinyl polymerization is dominant with AIET₃ in the presence of hexamethyl phosphoric acid triamide. On copolymerization of acrylamide with acrylonitrile, the acrylonitrile content in the copolymer increased with the addition of hexamethyl phosphoric acid triamide on AIEt₃.     

Separation of copolymers using high-performance liquid chromatography with polymeric stationary phase and liquefied carbon dioxide as adsorption promoting solvent

Chromatographic separation of copolymers depending on the chemical composition was studied by a solvent gradient method using liquefied carbon dioxide (CO2) as an adsorption promoting solvent. As the high polar stationary phase, non-bonded silica gel, crosslinked acrylamide (AA) gel and crosslinked acrylonitrile (AN) gel were utilized. All columns showed the typical normal phase type of adsorption. Polymeric stationary phases showed the higher sample recovery for styrene-methyl methacrylate (St-MMAs) copolymers, indicating suitability for quantitative analyses. The separations of butyl methacrylate (BMA)-methyl methacrylate, and 2,2,3,3,4,4,4-heptafluorobutyl methacrylate (FBMA)-methy methacrylate copolymers were also carried out, and the latter copolymers were separated based on the CO2-philicity with acrylonitrile column.