无分散剂微波辅助离子液体分散液液微萃取/胶束电动色谱检测食用油中丙烯酰胺和5-羟甲基糠醛残留

丙烯酰胺(AA)和5-羟甲基糠醛(5-HMF)主要通过美拉德反应形成,因其在食品中广泛存在且毒理效应显著而倍受关注。该文开发了一种无需分散剂的微波辅助离子液体分散液液微萃取结合胶束电动色谱分析食用油中AA和5-HMF的方法。通过实验优化了影响萃取回收率的因素,包括离子液体种类和体积、微波辅助萃取条件、样品体积以及胶束电动色谱的分离条件等。在最佳实验条件下,方法的线性范围为0.5～50μg/mL(r~2≥0.997 1),AA和5-HMF检出限(S/N=3)分别为0.11、0.70μg/mL,加标回收率分别为82.5%～96.2%和77.9%～95.9%,相对标准偏差分别为1.3%～5.2%和1.7%～4.9%。利用该方法在3种商品芝麻香油和1种餐馆自制花椒油中检出5-HMF,含量在1.1～3.3μg/mL之间。该方法简单、高效且经济环保,可应用于食用油中AA和5-HMF的分析测定。     

超高效液相色谱法同时测定烟用香精料液中的糠醛、5-羟甲基糠醛与5-甲基糠醛

建立了同时测定烟用香精料液中糠醛、5-羟甲基糠醛和5-甲基糠醛的超高效液相色谱(UPLC)方法。样品经流动相稀释、振荡、过滤后,采用C18(2.1 mm i.d.×100 mm,1.7μm)柱,以乙腈-水(10∶90)为流动相,在流速0.3 m L/min条件下等度洗脱分离,以二极管阵列检测器在波长280 nm下检测,外标法定量。该方法5 min内即可实现3种目标物的分离,5-羟甲基糠醛、糠醛和5-甲基糠醛的线性范围分别为0.004 2~40.00 mg/kg,0.004 6~30.00 mg/kg,0.006 9~30.00 mg/kg;相关系数(r2)分别为0.999 2,0.999 9和0.999 8;检出限(S/N=3)分别为1.24,1.37,2.06μg/kg;相对标准偏差(RSD,n=11)为0.1%~0.4%;加标水平为0.005 0~10.18 mg/kg时,3种化合物的回收率为91.7%~106.0%。该方法操作简便、分析快速、结果准确,适用于烟用香精料液中5-羟甲基糠醛、糠醛和5-甲基糠醛的检测。     

分光光度法测定酱油中5-羟甲基糠醛的研究

利用一阶导数分光光度法测定了酱油中5-羟甲基糠醛的含量。具体是,在酸性介质中,以硫代巴比妥酸为衍生试剂,在414nm波长下进行5-羟甲基糠醛的比色检测。该方法快速、准确、灵敏度高,线性范围为0.5~4μg/mL,相关系数为0.9995,能够满足食品安全检测的需要。     

乙烯焦油炭磺酸催化果糖脱水合成5-羟甲基糠醛

以蒸馏后的乙烯焦油重组分为原料,采用交联-磺化法制备了乙烯焦油炭磺酸。 利用红外光谱(FT-IR)、X射线衍射(XRD)、拉曼光谱(Raman)、热重分析(TGA-DTG)、扫描电子显微镜(SEM)等手段对该催化剂进行结构和性能表征。 结果表明,该催化剂呈现无定形石墨碳结构,且具有较高的酸量(4.20 mmol/g),表面的磺酸官能团是其关键活性中心。 并将该催化剂用于果糖脱水合成5-羟甲基糠醛(5-HMF)的反应,在130 ℃反应140 min,催化剂用量0.3 g、溶剂用量8 mL及助剂用量0.3 g的条件下,果糖转化率和5-HMF产率分别为96.2%和52.1%,分离得到的5-HMF纯度可达97.0%。催化剂循环使用5次后,果糖的转化率和5-HMF的产率分别保持在85.1%和40.8%以上。     

高效液相色谱法测定牛膝颗粒中5-羟甲基糠醛和蜕皮甾酮的含量

提出了高效液相色谱法同时测定牛膝配方颗粒中5-羟甲基糠醛和蜕皮甾酮的含量的方法。采用SHIMADZU shim-pack VP-ODS(4.6mm×250mm,4.6μm)柱;用两种不同配比的乙腈和水混合溶液作为流动相,梯度洗脱;检测波长为279nm(5-羟甲基糠醛)和245nm(蜕皮甾酮)。5-羟甲基糠醛和蜕皮甾酮的质量浓度分别在0.390～100mg.L-1和3.125～100mg.L-1范围内与峰面积呈线性关系,方法的检出限(3S/N)分别为1.95,2.01ng。5-羟甲基糠醛和蜕皮甾酮的平均回收率分别为99.7%,99.1%;相对标准偏差(n=5)分别为0.80%,0.67%。     

气相色谱-三重四极杆串联质谱法测定发酵乳中4种糠醛类物质

建立了气相色谱-三重四极杆串联质谱(GC-MS/MS)快速检测发酵乳中因热加工处理产生的羟甲基糠醛(5-HMF)、糠醛(F)、甲基糠醛(MF)、2-乙酰基呋喃(FMC)4种糠醛类物质。采用QuEChERS进行样品前处理,选择RTX-WAX色谱柱,在多反应监测模式(MRM)下对发酵乳中4种糠醛类物质进行测定,并优化了萃取试剂、盐析剂用量、净化剂用量。结果显示,在最佳条件下,4种糠醛类化合物的加标回收率为82.2%～118%,相对标准偏差(RSD)不大于10%。F、FMC、MF的线性范围为0.002～2 mg/L,5-HMF线性范围为0.02～2 mg/L,相关系数均不小于0.998,方法的定量下限(LOQs)和检出限(LODs)分别为3.0～45μg/kg和1.0～15μg/kg。该方法简便快速,灵敏度高,重现性好,满足定性定量要求。该方法对5种原味发酵乳和6种炭烧风味发酵乳的测定结果显示,炭烧风味发酵乳中4种糠醛类物质含量远高于原味发酵乳,表明炭烧工艺导致美拉德反应更加充分,间接说明过热处理会导致发酵乳中危害物增多,影响其营养价值和品质,该文为消费者提供了合理的选购建议与指导。     

反相高效液相色谱法测定糠酸、糠醇和糠醛

提出了反相高效液相色谱法（HPLC）同时测定糠酸、糠醇和糠醛的新方法,采用C18色谱柱,流动相为V（乙腈）：V（水）=50：50,流速为1.0 mL/min;检测波长为220 nm;柱温为25℃.在4 min内可以将3种组分完全分离.糠酸、糠醇、糠醛检出限（S/N=3）分别为：0.101、0.042、0.406 mg/L.平均回收率分别为101.4%、98.5%、95.3%.相对标准偏差（RSD）分别为0.87%、0.66%、0.43%.     

气相色谱-串联质谱法快速测定调味品中3种糠醛类物质

建立了同时测定调味品中糠醛、5-甲基糠醛和5-羟甲基糠醛的气相色谱-串联质谱法(GC-MS/MS)。对样品的前处理方法及GC-MS/MS分析条件进行优化,样品经乙酸乙酯萃取,GC-MS/MS多反应监测模式(MRM)进行测定。3种糠醛类物质在0.001～20 mg/L范围内均呈良好的线性关系,相关系数为0.999 0～0.999 5;检出限(S/N=3)均为0.005 mg/kg,加标回收率为86%～95%。该法简便、快速、溶剂用量少,可消除调味品中复杂基质的干扰,结果准确可靠、灵敏度高,适用于调味品中3种糠醛类物质的同时测定。     

双功能[Sn,Al]-Beta分子筛一步催化葡萄糖生成5-羟甲基糠醛

以部分脱铝的Beta分子筛为母体,采用同晶置换法将Sn植入骨架制备双功能[Sn,Al]-Beta分子筛,并应用于葡萄糖一步催化生成5-羟甲基糠醛(5-HMF)反应中.样品中Sn与Al的含量通过酸洗的浓度和酸洗的时间以及SnCl4处理的时间来控制.由于骨架中有与Al相关为B酸位,和Sn相关的L酸位,[Sn,Al]-Beta可作为一种双功能的固体酸催化剂.优化了[Sn,Al]-Beta催化葡萄糖一步催化生成5-HMF的反应参数,在最优Sn/Al比条件下,葡萄糖转化率为60.0%,5-HMF选择性为62.1%.     

气相色谱–质谱法测定速溶咖啡中糠醛和5-羟甲基糠醛

建立测定速溶咖啡中糠醛和5-羟甲基糠醛的气相色谱–质谱法。样品经乙腈提取,100 mg C18、50 mg强阳离子交换剂（SCX）、150 mg无水MgSO4净化,经HP-INNOWAX毛细管柱分离,选择离子扫描（SIM）模式,同位素内标法定量。糠醛、5-羟甲基糠醛的质量浓度在0.001～8.0μg/mL范围内线性关系良好,相关系数大于0.999,方法检出限为0.080～0.083 mg/kg,平均回收率为91.8%～96.8%,相对标准偏差为2.8%～6.5%(n=5)。该方法简单快速、灵敏可靠,为速溶咖啡中糠醛、5-羟甲基糠醛的提取和检测提供了可靠的技术支撑。     

利用手持技术改进测定乙醇分子结构实验

利用压强传感器代替排水集气法,改进测定乙醇分子结构实验的仪器装置,并探索最佳反应条件。另外,设计两个空白实验,结合压强变化曲线对实验误差进行相关讨论。     

光谱仪测试范围的扩展

由于石化行业的生产需要，其材质的使用具有多样性和广泛性，经常会出现顾客委托的测试样品的一个或几个元素跨越光谱仪现有测试程序测量范围的情况。本法通过对光谱仪测试原理的认识，根据光谱仪的测试能力及标样的采集，实现了一个或几个元素测量范围的扩展，并对其测量的影响因素进行了研究。     

Influence of viscosity of medium on processes of oxygen quenching of excited states of mesoporphyrin

The oxygen quenching rate constants for singlet and triplet excited states of the dimethyl ester of mesoporphyrin IX increase with decreasing viscosity of the medium and reach a maximum at a viscosity of approximately 0.4 mPa·sec, after which the rate constants begin to decrease. The drop in rate constant with increasing fluidity of the medium may be related to a nonequilibrium character of the elementary act in the interaction of the reactants in the solvent cage. In viscous media such as isopropyl alcohol, isobutyl alcohol, and isoamyl alcohol, the reaction radius is greater than the sum of the radii of the reacting particles. The long-range character of these processes is due to the relatively weak dependence of the quenching probability on distance.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 25, No. 2, pp. 161–167, March–April, 1989.     

Dichroism of absorption and polarization of phosphorescence of molecules of the closed form of nitrobenzospirothiopyran

The spectral-polarization characteristics of absorption and phosphorescence of molecules of the initial form of nitro-substituted indolinospirobenzothiopyran were studied in oriented polyethylene films and in solutions with different polarity. An oscillator model of the electron transitions responsible for the formation of absorption and luminescence spectra was suggested. It was established that the principal differences in the spectral and photophysical properties of the compound studied and its oxygen-containing analog are associated with the fact that the electronegativity of the S atom is lower than that of the O atom. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1143–1146, June, 1997.     

Neutral diterpenoids of oleoresins of five species of conifers of Transcarpathia

The compositions of the neutral diterpenoids of the oleoresins of five species of conifers growing in the Transcarpathia have been studied. It has been found that the oleoresins ofAbies alba M.,Larix decidua M., andPicea excelsa L. contain more than 50% of neutral diterpenoids. The group and qualitative compositions of the oxygen-containing diterpenoids have been determined. In the oleoresins ofAbies alba,Picea excelsa, andPicea abies tertiary alcohols — cis-abienol and isocembrol — predominate, while inLarix decidua the main component is the hydroxy ester larixyl acetate. Primary alcohols related to the resin acids have been found in all the oleoresins investigated. Features of the distribution of diterpenoids according to the species of conifers have been revealed. The results obtained are necessary for the chemotaxonomy of conifers of the family Pinceae.Novosibirsk Institute of Organic Chemistry, Siberian Branch, Academy of Sciences of the USSR. Translated from Khimiya Prirodynkh Soedinenii, No. 6, pp. 812–816, November–December, 1988.     

Determination of heats of detonation and influence of components of composite explosives on heats of detonation of high explosives

The heats of detonation of 20 simple high explosives and explosive mixtures were determined by means of an adiabatic detonation calorimeter designed by the authors. The results indicated that the performance of the instrument was reliable and the experimental data were very accurate. For explosive mixtures, there was a linear accumulative relationship between the heats of detonation of the explosive mixture and its components. Accordingly, the heats of detonation of explosive mixtures could be calculated directly from the heats of detonation of simple explosives and the characteristic heats of other components. The experiments showed that the gold or brass shell of the cylindrical charge could be substituted by a thick-walled porcelain shell, which had the advantage of cheapness.

     

物质分配系数的测定实验改进

实验教学目的是从解决实际问题出发,以实验技术训练和实验设计思想培养为目标。介绍了将单一的物质分配系数测定实验改进为综合实验,提高了实验效果及实验资源利用率。     

Calculation of enthalpies of hydrogenation of hydrocarbons

Sets of hydrogen molecule equivalents have been developed which permit the calculation of hydrogenation of different types of carbon-carbon bonds from ab initio total energies (3-21G and 6-31G* basis sets, and, to a more limited extent, for MP2/6-31G* data) of reactants and products. The calculated enthalpies of hydrogenation are in good agreement with experiment for unstrained molecules, with average errors on the order of 2 kcal/mol. The 6-31G* equivalents allow the enthalpies for strained molecules to be calculated accurately, but the 3-21G equivalents do not. The equivalents for both basis sets have been tested by calculating the enthalpies of hydrogenation of carbon-carbon bonds in nitrogen- and oxygen-containing organic molecules, free radicals, and classical carbocations. The results are in good agreement with experiment in most cases.     

非那雄胺合成工艺改进

非那雄胺能抑制5α-还原酶的活性,明显降低二氢睾酮水平,是一种治疗良性前列腺增生的有效药品。该合成工艺以甾烯酮酸为原料,将其与氯化亚砜反应,无须分离即与叔丁胺反应得17β-酰胺化合物,再氧化开环,环合,氢化,脱氢合成了非那雄胺。经元素分析、IR、1HNMR、13CNMR、MS分析表征了其结构。该法无须使用昂贵的2,2-二吡啶二硫化物和剧毒药品苯亚硒酸酐,且以乙酸铵代替氨气,降低了对设备的要求和腐蚀,更适用于工业生产。