阴/阳离子交换色谱-电感耦合等离子体质谱法分析鱼和贝类海产品砷的形态

采用阴(Hamilton PRP X100柱)阳(Dionex Ionpac CS- 10柱)离子交换色谱-电感耦合等离子体质谱联用技术,分别以pH 10.3的20 mmol/L NH4HCO3和pH 2.0的5 mmol/L吡啶溶液为流动相,建立了三价砷As(Ⅲ)、五价砷As(V)、一甲基砷酸MMA、二甲基砷酸DMA...     

高效色谱-电感耦合等离子体质谱法分析海藻类海产品中砷的形态

采用阴(Hamilton PRP-X100柱)阳(Dionex Ionpac CS-10柱)离子交换色谱-电感耦合等离子体质谱联用技术,分别以pH 10.3的20 mmol/L NH4HCO3和pH 2.0的5 mmol/L吡啶溶液为流动相,建立了As(Ⅲ)、As(Ⅴ)、一甲基砷酸(MMA)、二甲基砷酸(DMA)、砷甜菜碱AsB、砷糖PO4、砷糖OH、砷糖SO3、砷糖SO4砷形态的分析方法。采用微波消解法和超声溶剂提取法对不同海域10种紫菜和海带产品进行前处理,对As含量及其化学形态进行分析。实验表明,样品总砷的质量分数为1.7～38.7 mg/kg,样品萃取物中,As糖PO4和As糖OH为As的主要形态,其含量分别占可提取As的6.5%～67.7%和12.9%～86.2%,海带样品萃取物中还有As糖SO3和DMA被检测,其含量分别占可提取As的13.0%～52.1%和5.9%～17.4%。在紫菜和海带海藻类产品中,含As的化合物主要是毒性较低的有机砷。     

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%.     

HPLC-HG-AFS测定大气颗粒物中砷的形态

采用高效液相色谱-氢化物发生原子荧光光谱联用测定了北京大气颗粒物中As(III),As(Ⅴ),二甲基砷酸(DMA)和一甲基砷酸(MMA)的含量。研究了仪器条件、流动相组成和梯度洗脱程序对砷形态分离的影响。实验结果显示,在优化的色谱与氢化原子荧光检测条件下,采用pH6.0,浓度为10 mmol/L和200 mmol/L NH4H2PO4为流动相A和B,在1~3 min内用60%的A和40%的B洗脱使砷的4种形态达到最佳分离效。As(III),As(Ⅴ),DMA和MMA的检出限为1.45,1.22,1.91和1.64 mg/L,回收率为90.5%~93.2%,相对标准偏差为0.38%~1.7%。方法适用于大气颗粒物中砷的形态分析研究。     

HPLC-ICP-MS联用技术分析烟草中砷的形态

采用高效液相色谱-电感耦合等离子体质谱(HPLC-ICP-MS)联用技术对烟草中砷的形态进行分析研究。烟草样品经超纯水提取,采用阴离子交换柱,以30 mmol/L碳酸铵水溶液作流动相,成功分离了亚砷酸(As(III))、砷酸(As(V))、一甲基砷(MMA)和二甲基砷(DMA),检出限依次为0.15,0.16,0.17,0.16 ng/mL,加标回收率在73.8%~107.6%之间,相对标准偏差(RSD)均小于8.0%(n=3)。     

高效液相色谱-电感耦合等离子体-串联质谱法同时测定饲料中As(Ⅲ)、As(Ⅴ)、氨苯胂酸和洛克沙胂

建立了饲料中As(Ⅲ)、As(Ⅴ)、氨苯胂酸(p-ASA)和洛克沙胂(ROX)不同形态砷的高效液相色谱-电感耦合等离子体-串联质谱(HPLC-ICP-MS/MS)检测方法。样品经甲醇-水(1∶1,V/V)超声提取,用Shiseido MGⅡC18色谱柱(250×4.6 mm,5μm)对4种砷形态进行分离,以pH=4.7的6mmol/L四丁基氢氧化铵(TBAH)-甲醇(92∶8,V/V)溶液及pH=1.9的0.05%三氟乙酸(TFA)-甲醇(92∶8,V/V)溶液为流动相进行梯度洗脱。然后通过电感耦合等离子体质谱进行监测,外标法定量。结果表明,在优化的实验条件下,各形态砷在0~50μg/L范围内线性良好(R≥0.9999),As(Ⅲ)、As(Ⅴ)、氨苯胂酸(p-ASA)和洛克沙胂(ROX)的检测限分别为0.05、0.10、0.08、0.60μg/L,4种形态砷的加标回收率范围在85.9%~104.6%之间,相对标准偏差(RSD)均小于5%。通过对实际样品的检测,该方法适用于饲料中常见形态砷的检测。     

HPLC-ICP/MS联用同时分析中药材中的多种形态砷

利用高效液相色谱-电感耦合等离子体质谱(HPLC-ICP/MS)对中药材中的6种砷的形态(三价砷(As(Ⅲ))、五价砷(As(Ⅴ))、二甲基砷酸(DMA)、甲基砷酸(MMA)、砷甜菜碱(AsB)和砷胆碱(AsC))进行了同时分析.采用1.2mol/,L HCl浸提,Hamilton PRP-X100阴离子交换色谱柱分离...     

毛细管电泳紫外吸收法分离检测海洋生物样品中不同形态的砷化合物

本研究建立了对亚砷酸盐As(Ⅲ)、二甲基砷(DMA)、对甲基苯砷酸(p-As)、一甲基砷(MMA)、砷酸盐(As(Ⅴ)) 5种不同形态的砷化合物的毛细管区带电泳(CZE)分离紫外检测方法,研究了检测波长、缓冲体系种类、pH值及其浓度、分离电压、温度、进样时间等因素对5种形态砷化合物的分离度、灵敏度、重现性等的影响.结果表明,在25 ℃、195 nm、20 mmol/L NaH2PO4-5 mmol/L Na2B4O7(pH=6.25)缓冲溶液、20 kV运行电压、3.0 kPa压力进样10 s条件下,5种不同形态砷化合物在11 min内取得完全分离,5种不同形态砷化合物的迁移时间和峰面积的RSD为0.50%～1.51%和1.65%～3.36%,检出限(3S/N)为0.004～0.30 mg/L.本法成功地应用于虾米中不同砷形态含量的测定,其回收率在93%～106%之间.     

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。     

高效液相色谱-电感耦合等离子体串联质谱法同时测定土壤中的阿散酸、洛克沙胂及其降解产物

建立了高效液相色谱-电感耦合等离子体串联质谱(HPLC-ICP-MS/MS)同时测定土壤中阿散酸(p-ASA)、洛克沙胂(ROX)及其降解产物无机砷(i-As)(亚砷酸(As(Ⅲ))和砷酸(As(Ⅴ)))、一甲基砷(MMA)和二甲基砷(DMA)等5种砷形态的分析方法。以0.1 mol/L NaH_2PO_4-0.1 mol/L H_3PO_4(体积比9∶1)为提取剂,液固比为50 mL/g,样品经微波辅助提取(80℃,30 min)后,采用Hamilton PRP-X100阴离子交换柱(250 mm×4.1 mm,10μm),以60 mmol/L(NH_4)_2HPO_4-5%甲醇(pH 6.0)和水为流动相进行梯度洗脱,在15 min内实现了5种砷形态的良好分离。在优化条件下,各砷形态在0～500μg/L范围内线性良好(r~2≥0.999 1),检出限为0.043～0.080μg/kg(以As计),相对标准偏差为1.7%～3.8%。将该方法用于分析3种土壤样品,各砷形态的加标回收率为71.6%～106%。该方法简单、快速、准确、可靠,适用于土壤中阿散酸、洛克沙胂和常规砷形态的检测。     

Pd Close Coupled Catalyst

Europe III standards require significantly higher emissions reduction, especially for hydrocarbon (HC). For a typical vehicle, a large portion (up to 80 %) of the HC emissions occurs during cold start. A variety of technologies are under development to reduce cold start HC emissions, including close coupled catalysts1; electrically heated catalysts2 and hydrocarbon absorbers3. Among them, the close coupled catalyst gradually dominated the technologies4. A high performance close coupled cat…     

Covalently Coupled Immunostimulant Heterodimers

We report increased stimulation of dendritic cells via heterodimers of immunostimulants formed at a discrete molecular distance. Many vaccines present spatially organized agonists to immune cell receptors. These receptors cluster suggesting that signaling is increased by spatial organization and receptor proximity, but this has not been directly tested for multiple, unique receptors. In this study we probe the spatial aspect of immune cell activation using heterodimers of two covalently attached immunostimulants.     

Capillary Electrophoresis Coupled On-Line with Inductively Coupled Plasma Atomic Emission Spectrometry for Elemental Speciation

Capillary electrophoresis (CE) has become a powerful analytical technique for the separation of a variety of analytes ranging from small inorganic ions to large biomolecules such as proteins and nucleic acids. A selective and sensitive detector for CE has been one of the most important and challenging prerequisites for the growth of CE. On-column UV-Vis detectors are commonly used to determine the analytes separated by CE. However, these detectors are often not very selective. Other detection techniques such as mass spectrometry, laser induced fluorescence, amperometry, and inductively coupled plasma spectrometry have been investigated to provide a more sensitive and selective detection for the target analytes. However, relatively few studies have been published on the use of inductively coupled plasma atomic emission spectrometry (ICP-AES) as a means of detection in CE separation.     

Coupled deswelling of multiresponse microgels

In this article, we study the response of a thermosensitive and ionic microgel to various external stimuli where coupling between different contributions to the total osmotic pressure is needed to describe the observations. We introduce a new Flory solvency parameter chi ( T, Q, n) with strong dependence on the network charge, Q, and salt concentration, n. The scaling exponent for the salt-induced deswelling of the microgel is the signature of the coupling between the mixing and ionic osmotic pressures.     

Dinitrogen Splitting Coupled to Protonation

The coupling of electron- and proton-transfer steps provides a general concept to control the driving force of redox reactions. N₂ splitting of a molybdenum dinitrogen complex into nitrides coupled to a reaction with Brønsted acid is reported. Remarkably, our spectroscopic, kinetic, and computational mechanistic analysis attributes N−N bond cleavage to protonation in the periphery of an amide pincer ligands rather than the {Mo−N₂−Mo} core. The strong effect on electronic structure and ultimately the thermochemistry and kinetic barrier of N−N bond cleavage is an unusual case of a proton-coupled metal-to-ligand charge transfer process, highlighting the use of proton-responsive ligands for nitrogen fixation.     

高效液相色谱-电感耦合等离子体质谱技术测定海水中锡化学形态

建立了反相色谱-电感耦合等离子体质谱联用技术(HPLC-ICP-MS),用于测定海水中一丁基锡(MBT)、二丁基锡(DBT)、三丁基锡(TBT)和三苯基锡(TPhT)。分别使用两种不同色谱柱C18ACE和TC-C18,缓冲溶液V(acetonitrile)∶V(water)∶V(acetic acid)∶V(TEA)=65∶23∶12∶0.005%,在分别在流速0.2和0.4 mL/min下对4种不同形态的锡进行分离。所建立的方法在20μL进样量下,对DBT、MBT、TBT及TPhT的检出限分别为30、50、80及10 ng/L。对青岛沿岸海水分析的结果表明海水中DBT、TPT含量分别为35和20 ng/L,而MBT及TBT的含量则低于本方法的检出限。     

用毛细管电泳-激光诱导荧光-增强型电荷耦合检测器测定痕量氨基酸

本文对用毛细管电泳－激光诱导荧光－增强型电荷耦合检测器测定氨基酸衍生物进行了研究。考察了荧光黄异疏氰酸酯衍生氨基酸的各种条件。在优化条件下，10－8～10－6mol／L浓度范围内精氨酸与其衍生物的荧光强度呈良好的线性关系，最小可衍生化的精氨酸浓度为5×10－10mol／L。     

超级微波消解电感耦合等离子体质谱法 测定土壤中13种元素

建立了超级微波消解-电感耦合等离子体质谱（ICP-MS）测定多类型土壤基质中钒、铬、锰、钴、镍、铜、锌、砷、钼、锑、铊、铅和铀等13种元素含量的方法。采用超级微波消解法对样品进行前处理,比较了超级微波前处理与常规微波前处理消解效果,并优化了消解酸体系。在最优条件下,13种元素的的方法检出限（LOD）为0.0002~0.2 mg/kg,方法定量限（LOQ）范围为0.001~0.6mg/kg。在0~500 μg/L范围内线性回归系数（R2）在0.9996~1.0000,各元素加标回收率在76.3%~126%,此方法准确度可以满足复杂基体样品多元素同时测定的需求,一次样品前处理可实现18个样品的同时测定,相较于常规前处理方法大幅减少酸使用的同时更加安全、高效、不易污染样品,可为土壤重金属污染监测工作提供可靠的分析方法支撑。     

Coupled gas chromatography-atomic absorption spectrometry.

The specific, precise detection of volatile metal chelates has been obtained by coupling the effluent from a gas chromatograph directly to the burner head of a commerical atomic absorption spectrometer (AAS). Quantitation of chromium in the nanogram range has been accomplished with a detection limit of 1.0 ng. The chelation-extraction-gas chromatographic separation procedure coupled with the selective detection by AAS gives a relatively interference-free system that has been used to quantitatively analyse for chromium in standard biological materials NBS SRM 1571 Orchard Leaves and SRM 1569 Brewers Yeast. Metal chelates of iron, copper and cobalt have also been detected by this system.