电感耦合等离子体质谱法分析大鼠血、毛发及脏器中铅浓度及同位素比值

建立了电感耦合等离子体质谱(ICP-MS)同时测定铅浓度及同位素比值的方法,并应用于染毒大鼠血、毛发及组织脏器测定,以考察大鼠体内铅浓度及同位素比值分布情况及染毒剂量对其的影响.标准物质牛全血铅浓度测定结果为(278±4) μg/L,在证书标准值(283±18)μg/L范围内;测定10 μg/L Pb标准溶液的RSD<...     

胚胎期铅暴露对斑马鱼行为发育的影响

目的了解胚胎期铅暴露对斑马鱼胚胎及幼鱼行为的影响,以探讨铅的神经行为发育毒性。方法斑马鱼胚胎期暴露醋酸铅浓度分别为0、0.1、0.5、2.5和12.5μmol/L,观察24 hpf胚胎的自主运动,分析测试5 dpf幼鱼对光周期的刺激反应。结果各组胚胎自主运动观察结果依次为(5.22±1.02)、(6.25±1.46)、(6.12±0.92)、(5.46±0.92)、(4.62±0.81)次/min,与对照组比较,随着铅暴露浓度增加,胚胎自主运动次数呈高至低变化趋势,多组间差异有统计学意义(P0.05)。幼鱼活力也随着铅暴露浓度增加呈现由高至低变化,明亮期12.5μmol/L铅浓度组及黑暗期2.5μmol/L铅浓度组平均活力均较对照组显著降低(P0.05);12.5μmol/L铅浓度组亮转暗前后1 min活力改变量较对照组显著增高(P0.05),并且暗刺激后活力动态变化呈易激惹、易衰退状态。结论胚胎期铅暴露能影响斑马鱼胚胎自主运动及幼鱼活力状态,低浓度铅暴露以兴奋作用为主,高浓度铅暴露则呈现抑制作用为主,但其内在机制尚有待进一步研究。     

电感耦合等离子体质谱法分析小鼠组织中以及和DNA结合的贫铀浓度与235U/238U

在DU染毒动物模型基础上,采用ICP-MS技术同时测定各组织中铀浓度和235U/238U比值,分析DU在体内的分布和代谢规律;提取纯化肝肾组织中的基因组DNA,ICP-MS检测与DNA结合的DU浓度和235U/238U。以Pt为内标元素,补偿基体效应,组织中铀的检出限为0.0019～0.0981μg/kg;精密度(RSD)为0.92%～2.13%,回收率在100%±10%内。ICP-MS对贫铀气溶胶中235U/238U检测结果与经典的α谱仪检测结果相吻合。DNA样品采用中性溶液稀释,DNA中铀元素检出限为0.0016μg/kg DNA,回收率为98.3%±7.3%。样本测定结果显示,肾脏和骨骼对贫铀的蓄积能力最强,脑组织几乎不受贫铀影响,其它组织的DU蓄积能力介于二者之间。在肾、肝组织中,DU可以与DNA发生结合,与肾DNA结合更持久。组织中235U/238U随染毒铀同位素组成和浓度发生规律性改变。铀浓度与235U/238U均可以作为衡量核素污染类型和程度的敏感指标。     

胎儿脐带血铅水平与钙、锌、铁的关系研究

目的研究胎儿脐带血中的铅与钙、锌、铁的含量以及两两之间的相关性。方法采用原子吸收光谱法对398例脐带血铅和钙、锌、铁的含量进行测定,并对它们进行相关性分析。结果 398例脐带血铅和钙、锌、铁的质量浓度分别为铅(37.96±17.78)μg/L、钙(1.51±0.29)mmol/L、锌(30.01±11.14)μmol/L、铁(8.63±1.39)mmol/L。线性回归分析显示:铅与钙(r=-0.563,P0.01)、铅与锌(r=-0.424,P0.01)有相关性,铅与铁无显著相关(r=0.018,P0.05)。结论随着胎儿体内血铅水平的上升,二价元素钙、锌含量有下降趋势,即中毒元素铅会干扰胎儿体内的必需二价元素的代谢。     

二硫化碳对机体铜、锌水平的影响

为观察二硫化碳（CS2）对机体铜，锌水平的影响，对某化纤厂35名接触CS2工人和41名非接触工人的血铜，锌值进行调查，比较，并进行了动物染毒实验。SD大鼠吸入CS2浓度分别为5和50mg/m^3，每日5h，每周6d，连续6个月，于染毒2，4，6个月时测定血浆铜，锌值及染毒6个月时肝脏铜，锌含量。结果显示，CS2接触组工人血铜，锌水平较对照组显著降低（P＜0．05）。在CS2染毒6个月时，50mg/m^3 CS2染毒组血浆及肝脏铜水平均较对照组及5mg/m^3 CS2染毒组显著降低（P＜0．05）。可见接触CS2能干扰机体铜，锌代谢，导致体内铜，锌含量减少。     

市场海产品铅含量分析以及小鼠对铅的吸收研究

用电感耦合等离子体质谱（ICP -MS）测量了深圳市市场上销售的花甲、生蚝、鲍鱼等16种海产品,分析了铅含量以及同位素比,其中响螺、青口贝、生蚝的铅质量分数最高,分别为（1．52±0．21）,（1．66±0．23）,（1．16±0．15）μg/g 干质量,超标,其它小于1．00μg/g 干质量,同位素比207 Pb/206 Pb 为0．76～0．89之间。将花甲,鲍鱼,生蚝,喂食昆明小白鼠（每组5只,质量35～38 g）,喂食前后（24 h）眼球取血0．030 mL 左右对比分析海鲜中铅进入血液的量,结果表明,生蚝喂食后铅有明显的上升,其中孕鼠生物有效性显著大于对照鼠。通过用水合醋酸铅加入鼠粮中喂食哺育期间母鼠,而被哺乳的新生小鼠血铅含量和母鼠喂食铅成正比,最后一组小鼠血液铅达到（1．95±0．35）μg/g,该组一直喂养2个月（8周）后小鼠个体体质量（15±4 g）与对照（26±5 g）相比显著小。实验表明高含量铅的海产品对孕妇以及哺乳期间母亲和婴儿更为危险。     

警惕儿童铅中毒

儿童玩具和学习用品的含铅量普遍较高。有报告表明 ,7种玩具表面油漆中含的可溶性铅已超过国际最高允许量。学生常用的铅笔 ,有 6类超标 ,含铅量最高的超标 4 12倍 ;课桌、椅的棕黑色油漆层超标 36 7倍 ;彩色蜡笔足以引起儿童铅中毒。有关专家指出 :正常人血液中不应含铅 ;儿童铅中毒诊断标准为血铅水平超过或等于 0 4 83μｍｏｌ/Ｌ。铅主要通过消化道和呼吸道进入人的体内 ,而铅往往最容易被儿童吸收。除了前面提到的那些铅污染源 ,还有含铅汽油的燃烧、含铅油漆的风化、工业污染等 ,都是铅尘的重要来源。一旦发生铅中毒 ,会有以下表现…     

南通市1118例患儿发锌、铅含量与分析

为了解南通市患儿体内微量元素锌、铅含量及其关系,采用火焰原子吸收分光光度法对1 118例发锌、铅进行了检测分析,按性别、年龄做了锌、铅的相关分析。结果表明,缺锌率为77.91%;铅含量均在正常范围内;南通市患儿锌、铅的x-±s分别为(83.6±24.8)、(1.4±0.7)μg/g;低锌和低铅污染无负相关关系。     

铜质水嘴中铅含量与析出量的相关性探讨

试验探讨铜质水嘴中铅含量与析出量的关系。对一系列含铅标准铜片按照GB/T 17219–1998《生活饮用水输配水设备及防护材料的安全性评价标准》要求进行浸泡试验,使用原子吸收光谱法或电感耦合等离子体质谱法检测浸泡液中的铅含量,再利用20个已知铅含量的铜质水嘴样品进行析出量的检测和验证。得到铜质水嘴中铅含量与析出量的关系。试验结果表明:大部分内腔有电镀层的铜质水嘴,铅析出量小于5.0μg/L;内腔无电镀层的铜质水嘴中铅含量小于0.5%时,铅析出量小于5.0μg/L,符合GB/T 17219–1998标准要求。     

同位素稀释-高效液相色谱-质谱联用技术检测大鼠血浆中的芥子气水解产物

应用同位素稀释-高效液相色谱-质谱联用技术(LC-MS/MS),建立了同时定量检测血浆中芥子气水解代谢产物硫二甘醇(TDG)和二羟乙基亚砜(TDGO)的方法.应用甲醇和乙腈混合溶剂沉淀染毒大鼠血浆中蛋白,采用ZORBAX-C18色谱柱(100 mm×3.0 mm,3.5μm),以5 mmol/L甲酸铵-甲醇梯度洗脱分离待测物.以d8-TDG为内标,在正离子多反应监测模式下定性和定量分析TDG和TDGO.方法学验证结果表明,TDG在5～800 μg/L和TDGO在0.5～80.0 μg/L范围内均呈良好的线性关系(r2＞0.991),定量限分别为5和0.5 μg/L,加标回收率在101％～118％之间,方法的日内和日间精密度(RSD)均小于10％.对SD大鼠(n=6)采用皮下注射方式进行染毒后采样测定,代谢动力学参数计算结果显示,TDG和TDGO的达峰时间(tmax)分别为30和60 min,峰值浓度(cmax)为(1724±227)μg/L和(301±115)μg/L,血浆浓度-时间曲线下面积(AUC)为(3286±249) μg· h/L和(1010±363) μg· h/L.     

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%.     

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.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

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.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.