HPLC-ICP-MS测定中药中砷的形态

报道了高效液相色谱-电感耦合等离子体质谱(HPLC-ICP-MS)联用技术测定中药中砷的形态.采用阴离子交换柱,以含0.2 mmol/L乙二胺四乙酸(EDTA)和2 mmol/L NaH2PO4的水溶液为流动相,pH 6.0,流速为1.0 mL/min,成功分离了亚砷酸(AsⅢ)、砷酸(AsⅤ)、甲基砷(MMA)和二甲基砷(DMA).检出限分别为0.67 μg/L (AsⅢ),0.85 μg/L (DMA),0.43 μg/L (MMA),0.70 μg/L (AsⅤ).中药样品经过(1 1)甲醇水溶液超声提取,离心、过滤、氮气吹干甲醇,超纯水定容.样品加标平均萃取回收率分别为: 92.8% (AsⅢ),108% (DMA),104% (MMA),101% (AsⅤ),RSD (n=7)均小于10%.     

方便面中砷元素的形态分析

建立了硝酸提取,高效液相色谱一原子荧光联用技术测定方便面中不同砷形态的分析方法。样品经0．15mol／L盐酸溶液超声提取后离心过滤,上机测试。实验表明：砷的4种形态亚砷酸[As（Ⅲ）]、砷酸[As（V）]、一甲基胂酸（MMA）和二甲基胂酸（DMA）的线性范围为0-50μg／L,相关系数（r）均优于0．9990,检出限在2～8μg／L之间,砷各形态的测量重复性（以RSD表示）均小于5％,样品的加标回收率为78％-118％。同时用原子荧光光度计检测了样品中总砷,并将两种方法测定结果进行了对比,结果符合理论以及文献报道。该方法操作简单快速、结果准确可靠,适用于方便面中砷形态的分析测定。     

HPLC–AFS联用测定海产品中砷的形态

建立了高效液相色谱–原子荧光分光光度法测定海产品中无机砷(As V,AsⅢ)、有机砷(DMA,MMA,AsB)含量的方法。样品经含10%(体积分数)HCl的提取液振荡提取、离心分离、二路形态分析预处理、高效液相色谱分离,用原子荧光光度计检测As(Ⅲ),DMA,MMA,As(V);四路条件(过氧化氢氧化和开启紫外灯)形态分析预处理装置处理,高效液相色谱分离,原子荧光光度计测定AsB。As(Ⅲ)线性范围为0～100.00μg/L,r2=0.999 7;DMA线性范围为0～100.00μg/L,r2=0.999 3;MMA线性范围为0～100.00μg/L,r2=0.999 0;As(V)线性范围为0～100.00μg/L,r2=0.999 1;AsB线性范围为0～200.00μg/L,r2=0.999 4。3个样品加标回收率为As(Ⅲ)86.7%～89.4%,DMA 111.2%～117.0%,MMA 109.7%～111.6%,As(V)83.8%～90.7%,AsB 88.3%～90.4%。用该方法测定虾仁(干)5个价态测定结果的相对标准偏差为3.07%～9.93%(n=6)。5个价态的检出限(S/N=2)为As(Ⅲ)0.29μg/L,DMA 0.36μg/L,MMA 0.27μg/L,As(V)0.56μg/L,AsB 1.46μg/L。该方法适用于海产品中As(Ⅲ),DMA,MMA,As(V),AsB含量的测定。     

HPLC-AFS联用测定海产品中砷的形态

建立了高效液相色谱-原子荧光分光光度法测定海产品中无机砷(As V,AsⅢ)、有机砷(DMA,MMA,AsB)含量的方法.样品经含10％(体积分数)HC1的提取液振荡提取、离心分离、二路形态分析预处理、高效液相色谱分离,用原子荧光光度计检测As(Ⅲ),DMA,MMA,As(v);四路条件(过氧化氢氧化和开启紫外灯)形态分析预处理装置处理,高效液相色谱分离,原子荧光光度计测定AsB.As(Ⅲ)线性范围为0～100.00 μg/L,r2=0.9997;DMA线性范围为0～100.00 μg/L,r2=0.9993;MMA线性范围为0～100.00 μg/L,r2=0.9990;As(Ⅴ)线性范围为0～100.00 μg/L,r2=0.999 1;AsB线性范围为0～200.00 μg/L,,r2=0.9994.3个样品加标回收率为As(Ⅲ)86.7％～89.4％,DMA 111.2％～117.0％,MMA 109.7％～111.6％,As(Ⅴ) 83.8％～90.7％,AsB 88.3％～90.4％.用该方法测定虾仁(干)5个价态测定结果的相对标准偏差为3.07％～9.93％(n=6).5个价态的检出限(S/N=2)为As(Ⅲ)0.29 μg/L,DMA 0.36 μg/L,MMA 0.27 μg/L,As(V) 0.56 μg/L,AsB l.46 μg/L.该方法适用于海产品中As(Ⅲ),DMA,MMA,As(V),AsB含量的测定.     

高效液相色谱-电感耦合等离子体质谱法分析尿中6种砷形态

采用高效液相色谱-电感耦合等离子体质谱法（HPLC-ICP-MS）分析人尿中砷甜菜碱（AsB）、二甲基砷（DMA）、砷胆碱（AsC）、亚砷酸盐（As（Ⅲ））、一甲基砷（MMA）、砷酸盐（As(V)）6种砷形态。样品经水稀释后，采用Dionex IonPac As7阴离子交换色谱柱为分析柱，20 mmol/L碳酸铵（2%甲醇）和100 mmol/L碳酸铵（含2%甲醇）为流动相，梯度洗脱，HPLC-ICP-MS分析砷形态。6种砷形态在0～100μg/L范围内线性关系良好，相关系数（r）均大于0.999，检出限为0.05～0.15μg/L，不同浓度水平砷形态的相对标准偏差（RSD）均小于5.0%。3种不同浓度水平的加标回收率为91.8%～108%，有证标准物质“冷冻人尿中砷形态”（NIST SRM 3669）中5种砷形态的测定结果在标准值范围内。实验结果表明，该方法准确可靠、灵敏度高、分析时间短，适用于人尿中砷形态的分析测定。同时研究了食用不同含砷食物后尿中砷形态的种类，结果显示不同的含砷食品，其砷在人体内的代谢转化不同。     

利用LC-AFS与ICP-OES测定污泥中砷形态及总砷含量

应用液相色谱和原子荧光联用(LC-AFS)技术以及在线紫外消解技术分析了污泥中三价砷(As(Ⅲ))、一甲基砷(MMA)、二甲基砷(DMA)、五价砷(As(Ⅴ))和砷甜菜碱(AsB) 5种砷形态含量,并利用电感耦合等离子体发射光谱(ICP-OES)测定了总砷(T-As)含量。通过对液相色谱分离、柱后衍生条件的优化,确定流动相为15 mmol/L (NH_4)_2HPO_4,pH 6. 0,载流5%(体积分数) HCl,还原剂为含5 g/L NaOH的10 g/L KBH_4溶液,5种砷形态可在10 min内得到分离、测定。结果表明,总砷含量与各形态砷总和接近,相对标准偏差(RSD)在5%之内; As(Ⅲ)、As(Ⅴ)、MMA、DMA、AsB的检出限(以As计)分别为0. 3、2. 1、1. 4、1. 1、0. 7μg/L,总砷的检出限为0. 8μg/L,且在线性范围内各砷形态和总砷标准曲线的相关系数均大于0. 999。该方法前处理便捷,结果准确、重复性好,可为环境污泥中砷形态分析提供技术基础。     

碱性模式氢化物发生原子荧光光谱法测定铁矿石中砷

建立了碱性模式氢化物发生原子荧光光谱法测定铁矿石中砷的最佳仪器和实验条件。采用微波消解分解样品，在硫脲和L-半胱氨酸存在下将As（Ⅴ）还原为As（Ⅲ），以1mol／L KOH作为介质，以0．75mol／L H3PO4作为载流，原子荧光光谱法测定样品中的砷。方法检出限为0．35μg／L，RSD在2．0％。9．4％之间，加标回收率95％～103％。对标准样品进行分析验证，结果与标准值相符。应用于铁矿样品的测定，结果满意。     

氢化物发生-冷阱捕获-色谱分离-原子吸收法测定天然水中砷的形态

研究建立了氢化物发生－冷阱捕获－色谱分离－原子吸收方法测定天然水中四种主要砷形态。测试系统自行组装，色谱住填料采用ChromosorbGAW－DMCS（粒径0．3～0．45mm），其上涂布3％OV－101。方法的检出限以砷计分别为：As（V）0．51ng，As（Ⅲ）0．43ng，MMA0．38ng，DMA067ng；12ng砷标准偏差As（Ⅴ）4．21％，As（Ⅲ）3．56％，MMA3．23％，DMA5．46％。在0～50ng砷量范围标准曲线线性关系良好。该法适用性广，已用于湖水、河水、海水和地下水等不同水样神形态测定，加标回收率93．5％～104．9％。给出了上述水样四种砷形态的分析结果。     

基于HPLC-ICP-MS的海螵蛸中不同砷形态含量及其转移率研究

建立了高效液相色谱-电感耦合等离子体质谱（HPLC-ICP-MS）测定海螵蛸药材中多种砷形态的分析方法，并研究了海螵蛸药材煎煮后砷及砷形态的转移率。样品采用0.02 mol/L乙二胺四乙酸二钠（EDTA-2Na）溶液超声提取60 min，以Dionex IonPac As7阴离子交换柱为色谱柱，2 mmol/L和100 mmol/L碳酸铵溶液为流动相进行梯度洗脱。结果显示，27批海螵蛸药材中均检出砷甜菜碱（As B）和砷胆碱（As C），其中26批检出二甲基砷（DMA）,10批检出一甲基砷（MMA）,1批检出微量亚砷酸（AsⅢ），并发现3个未知砷形态；海螵蛸药材水煎煮后砷及砷形态的平均转移率均大于50%，且存在个体差异。该方法准确度高，专属性好，明确了海螵蛸药材中砷形态的分布规律，并揭示了海螵蛸药材在煎煮过程中砷及砷形态的转移规律，可为海螵蛸药材的安全性评价奠定基础。     

超声提取-高效液相色谱-电感耦合等离子体质谱法测定水产品中的5种形态的砷

称取经匀浆处理后的样品1.000 0g,加入48mL的0.5mmol·L-1碳酸铵溶液-甲醇(99+1)混合液(pH 7.8),涡旋混匀后,超声提取40min,加入2mL的3%(φ)乙酸溶液,于4℃静置5min,以8 000r·min-1转速于4℃离心10min,取上清液过0.45μm滤膜,收集2mL滤液,采用Hamilton PRP-X100阴离子分析柱(250 mm×4 mm,10μm)进行分离,以pH 7.8的0.5mmol·L-1碳酸铵溶液-甲醇(99+1)混合液及pH 8.5的20mmol·L-1磷酸氢二铵溶液为流动相进行梯度洗脱,采用电感耦合等离子体质谱法测定洗脱液中的三价砷[(As(Ⅲ)]、五价砷[(As(Ⅴ)]、砷甜菜碱(AsB)、一甲基砷(MMA)和二甲基砷(DMA)。5种形态的砷的线性范围在100μg·L~(-1)以内,检出限(3S/N)为0.2~0.6μg·L~(-1),加标回收率为89.6%~102%,测定值的相对标准偏差(n=6)为0.11%~3.8%。     

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%.     

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.     

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.     

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.     

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.     

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.     

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.