木制儿童用品中6种木材防腐剂的迁移规律研究

基于气相色谱-串联质谱(GC-MS/MS)技术建立了6种防腐剂总量及迁移量的测定方法,通过搭建迁移装置并模拟实际暴露场景,对自制阳性样品中6种防腐剂在模拟唾液和汗液中的迁移规律进行研究,并计算出不同时刻的迁移率。结果表明,在迁移2 min~96 h范围内,防腐剂的迁移量均随时间延长而逐渐增大,最终达到迁移平衡,迁移率为2.1%~61.7%(唾液),2.2%~86.4%(汗液)。在样品与模拟液仅接触2 min时有6种物质检出,迁移率分别为2.1%~4.2%(唾液)和2.2%~3.3%(汗液)。部分实际样品中检出了2,4-二氯苯酚和2,4,6-三氯苯酚,鉴于儿童日常生活中短时间持续接触样品的特点,选取两个实际阳性样品测定了其在2~30 min的迁移量及迁移率。     

液相色谱-串联质谱法测定食品中甲基磺草酮

食品用乙腈-水(3+1)溶液进行提取,经凝胶色谱、固相萃取柱净化后,用液相色谱-串联质谱法进行测定和确证,外标法定量。色谱分离用甲醇和甲酸-水(0.1+99.9)溶液以不同体积比混合为流动相梯度洗脱,采用负离子模式电喷雾离子源在多反应监测模式下进行检测。甲基磺草酮的质量浓度在0.01~0.2 mg·L-1范围内与其峰面积呈线性关系。以4种食品样品为基体,加入3种浓度水平的甲基磺草酮标准做回收试验,测得回收率在73.2%~100.6%之间;测定值的相对标准偏差(n=10)在4.1%~11%之间。     

分散液液微萃取-高效液相色谱法同时测定烟用接装纸中Cr^(3+)和Cr^(6+)的含量北大核心CSCD

用20 mL水超声提取2 g剪碎后的烟用接装纸样品30 min,分取8 mL提取液,加入200 mmol·L^(-1)二乙基二硫代氨基甲酸钠(螯合剂)溶液100μL,在体系酸度为pH 6.0条件下,于45℃反应10 min。反应结束后,加入正十二醇(萃取剂)60μL和甲醇(分散剂)100μL,涡旋,离心,取上层有机相,用甲醇定容至0.5 mL,过滤至色谱瓶中待测。以ZORBAX SB-C_(18)色谱柱为固定相,以不同体积比的甲醇-水混合液为流动相进行梯度洗脱,分离后的目标物用二极管阵列检测器于258 nm进行检测。结果显示:Cr^(3+) 、Cr^(6+)标准曲线的线性范围均为2.00~100.00μg·L^(-1),检出限(3S/N)分别为3,6μg·kg^(-1);对实际样品进行加标回收试验,Cr^(3+) 的回收率为90.7%~105%,测定值的相对标准偏差(RSD,n=7)为4.2%~7.3%,Cr^(6+)的回收率为84.1%~106%,测定值的RSD(n=7)为4.5%~7.6%;Cr^(3+) 、Cr^(6+)的富集因子分别为25.6和9.5;方法用于5份实际样品分析,其中4份样品中均检出Cr^(3+) 和Cr^(6+),并且Cr^(6+)检出量均比Cr^(3+) 检出量高。     

超声辅助分散液相微萃取-高效液相色谱法测定蜂蜜中的咖啡因

采用超声辅助分散液相微萃取技术结合高效液相色谱法测定蜂蜜中的咖啡因。将样品用水溶解配制成100g·L-1样品溶液,取7.5 mL样品溶液,加入三氯甲烷120μL和甲醇1.5mL,混匀后超声5min,离心后吸取5μL沉积相,在WondasilTM C18色谱柱上分离,以甲醇(1+1)溶液为流动相进行洗脱,紫外检测波长为274nm。咖啡因的线性范围为10.0~500μg·L-1,检出限(3S/N)为9μg·L-1。测定值的相对标准偏差为2.7%~4.1%,加标回收率在96.6%~104%之间。     

超高效液相色谱-串联四极杆飞行时间质谱法测定人体尿液中14种内源性甾体激素含量

样品5.000 0g,加pH 6.8的磷酸缓冲溶液2.0mL、β-葡萄糖醛酸甙酶150μL混合,于55℃培养2h,冷却至室温,用乙醚5mL超声5min,提取2次。合并提取液,经氮气吹干后,加甲醇(3+7)溶液5mL溶解残渣,再经Oasis HLB固相萃取柱净化,用甲醇-乙腈(1+1)溶液5mL洗脱。净化液经氮气吹干,用乙腈(95+5)溶解并稀释至1mL后进行色谱分离,以HSS T3色谱柱为固定相,以不同体积比的乙腈和含0.1%(体积分数)甲酸的5mmol·L~(-1)乙酸铵溶液的混合液为流动相进行梯度洗脱。质谱分析中采用电喷雾离子源和全信息串联质谱采集模式。14种内源性甾体激素的质量分数在一定范围内与其峰面积呈线性关系,检出限(3S/N)在0.5~5.0μg·kg~(-1)之间。按标准加入法在3个浓度水平上进行回收试验,回收率在80.6%~99.2%之间,测定值的相对标准偏差(n=6)在1.1%~7.9%之间。     

烟草中挥发性和非挥发性有机酸的快速测定

建立了气相色谱-质谱(GC-MS)法快速测定烟草中22种非挥发性、挥发性有机酸的分析方法。采用对甲苯磺酸-硫酸-甲醇(PTSA/H2SO4/CH3OH)酯化试剂对烟草样品进行一次酯化,生成的有机酸酯用GC-MS进行分析。结果表明,酯化时间从20 h缩短到1 h,非挥发酸回收率在93.4%~103.2%之间,相对标准偏差(RSD)小于4.2%;挥发性有机酸回收率在89.2%~99.1%之间,RSD小于3.5%。该方法具有简便、快速,结果准确等特点,用于测定部分烟草样品的挥发性、非挥发性有机酸,取得了满意的结果。     

高效液相色谱法同时测定化妆品中14种禁用着色剂

采用高效液相色谱建立了同时测定化妆品中14种禁用着色剂(吖啶黄、溶剂蓝35、溶剂红49、酸性紫49、氯化四甲基副玫瑰苯胺、颜料橙5、颜料红53、氯化五甲基副玫瑰苯胺、苏丹红Ⅱ、氯化六甲基副玫瑰苯胺、苏丹红Ⅳ、罗丹明B、分散黄3、苏丹红Ⅰ)的分析方法。待测化妆品样品经四氢呋喃分散,并对目标物进行提取后,用含有醋酸铵的甲醇-水混合溶液将基质析出,提取液经离心过滤后,以10 mmol/L的醋酸铵溶液-乙腈作为流动相在Agilent poroshell 120 EC-C18(2.7μm,3.0 mm×100 mm)色谱柱上梯度洗脱进行分离,检测波长为416,514,590 nm。以目标物的色谱保留时间和紫外光谱图进行定性,以色谱峰的峰面积用标准曲线外标法进行定量。在优化条件下,各目标物的线性范围为0.2~20μg/mL,相关系数均大于0.999。14种禁用着色剂的定量下限为3~10μg/g。在低、中、高3个加标水平下,各目标物的回收率为91.3%~110.9%,相对标准偏差(RSD)均低于10%。方法准确、简便、灵敏、可靠,可用于化妆品中此14种禁用着色剂的定量测定。     

应用超临界流体萃取分离-气相色谱-质谱分析法建立中药温郁金的指纹图谱及其系统聚类分析

收集生长于浙江省瑞安市8个产地的温郁金样品14批次,分别经清洗、冷冻干燥及碾磨粉碎,得到通过0.425mm筛孔药筛的粉末状样品14个。称取此样品各30g,分别按试验选定的最佳条件[萃取温度35℃,萃取压力15MPa,萃取时间(静态30min,动态90min)]进行超临界流体萃取分离,所得萃取物收集于甲醇5mL中,并进行气相色谱-质谱法(GC-MS)分析。色谱分离采用HP-5ms石英毛细管色谱柱和在50~220℃之间程序升温模式;质谱测定采用电子轰击离子源(EI),在质荷比(m/z)50~650内进行扫描。所得总离子流色谱图中共有50多个色谱峰,选择保留时间在40min以内的共有峰26个作为考察对象,选择保留时间为17.12min的莪术二酮为参考峰,计算共有峰的相对保留时间α和峰面积百分比S以及各样品与S3的S值的最大差值ΔS(Max)%,并建立了14个样品的指纹图谱。根据GC-MS分析所得结果并与NIST 14谱库比对,对共有峰作出鉴定。通过SPSS 16.0软件,采用系统聚类分析法对所分析的14批次温郁金样品的指纹图谱进行分类比较。应用指纹图谱对2个市售温郁金产品作了组分鉴定和产地认定。     

超高效液相色谱-质谱法测定饮用水中14种氟喹诺酮类抗生素的残留量

采用超高效液相色谱-质谱法测定饮用水中的14种氟喹诺酮类抗生素的残留量。饮用水样品经Oasis HLB(200mg/6mL)固相萃取柱富集。柱上的浓集物用甲醇洗脱,洗脱液以Acquity UPLC BEH C_(18)色谱柱为分离柱,以不同体积比的0.1%(体积分数)甲酸溶液和0.1%(体积分数)甲酸乙腈溶液的混合液为流动相进行梯度洗脱,采用电喷雾正离子模式进行质谱检测。14种氟喹诺酮类抗生素均在一定的质量浓度范围内与其峰面积呈线性关系,方法的检出限(3S/N)在0.04~1.8ng·L~(-1)之间。以空白样品为基体进行加标回收试验,所得回收率在69.2%~85.2%之间,测定值的相对标准偏差(n=6)在4.5%~11%之间。     

气相色谱-质谱法测定木塞中10种多氯苯酚的残留量

采用气相色谱-质谱法同时测定木塞中10种多氯苯酚的残留量。样品经甲醇萃取后,在碳酸钾溶液中用乙酸酐乙酰化后再用正己烷萃取,萃取液经DB-5MS毛细管色谱柱分离,质谱分析中选择电子轰击正离子源和选择离子监测模式。10种多氯苯酚的线性范围为1.0~100.0mg·L~(-1),检出限(3S/N)在0.03~0.21mg·kg~(-1)之间.加标回收率在88.4%~104%之间,测定值的相对标准偏差(n=6)在2.1%~4.6%之间。方法用于市售木塞中10种多氯苯酚的测定,检出率为77.8%。     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.