化学蒸汽发生/电感耦合等离子体质谱法测定近岸及河口海水中的超痕量砷、锑、铋、锗、锡、汞

建立了化学蒸汽发生(CVG)电感耦合等离子体质谱(ICP MS)同时测定近岸及河口海水中超痕量As、Sb、Bi、Ge、Sn和Hg元素的方法.研究了CVG过程中KBH4、盐酸和硫脲的浓度以及样品流速、载气流速、海水样品盐度等对方法分析性能的影响.结果表明,在0.70％6盐酸、0.10 g/L硫脲、11.0 g/L硼氧化钾...     

Ultra-trace Analysis of Metosulam,a New Triazolopyrimidine Herbicide,in Soil Using LC-UV and TSP-LC-MS

Abstract

Metosulam (DE-511), N-(2,6-dichloro-m-tolyl)-5,7-dimethoxy-[1,2,4] triazolo [1,5a]pynmidine-2-sulphonamide is a new selective herbicide developed for the control of broadleaf weeds in cereals and maize.

The application of new generation low use rate herbicides, such as metosulam, has in turn created the need for the development of ultra-trace residue methodologies. To help investigate the environmental impact of metosulam, levels at sub-part per billion (μg/kg) in soil were determined.

Application of capillary gas chromatography, with various injector systems, was unable to analyse metosulam methyl derivative due to the inherent thermal instability of the molecule. Liquid chromatography with ultraviolet detection (LC-UV) was used to quantify residues of the herbicide following a series of selective clean-up procedures. The chosen methodology used simple reagents plus standard equipment and although the molar absorbtivity of metosulam is poor, analysis of soils of various texture classes at the desired sensitivity level, was achieved.

Thermospray Liquid chromatography with mass spectrometry (TSP-LC-MS) was used as a confirmatory technique for the analysis of metosulam in the same soils. Excellent agreement between the two techniques was observed.

Details of the clean-up procedures used to produce desired selectivity and the relative merit of the two detection systems are discussed.     

3,4-二巯基甲苯衍生化法结合SPME/GC-MS技术分析尿样中超痕量氯乙烯基胂酸

选取氯乙烯基胂酸(CVAOA)为生物标志物,建立了路易氏剂染毒尿样中超痕量CVAOA的分析方法。采用正交试验,优化了CVAOA的巯基化衍生方法,选取3,4-二巯基甲苯(DMT)作为衍生试剂,CVAOA与DMT的用量摩尔比为1∶1 000,常温衍生5 min,可达到最高的衍生效率;之后在优化的顶空-固相微萃取(HS-SPME)条件下富集纯化衍生产物CVAOA-DMT;使用气相色谱-质谱/选择离子监测模式(GC-MS/SIM)进行定性定量分析。该方法在50.0 pg/m L~500 ng/m L浓度范围内呈良好的线性(r2=0.998 5),相对标准偏差(RSD)小于10%,检出限可达7.6 pg/m L,定量下限为23 pg/m L。对低、中、高3种浓度的路易氏剂染毒尿样进行检测,回收率为97.6%~105%,RSD为4.4%~7.1%。该方法分析灵敏度高,具有良好的准确度、精密度和普及性,可被广泛推广和使用。     

Optical molecular fluorescence determination of ultra-trace beryllium in occupational and environmental samples using highly alkaline conditions

Exposures to beryllium (Be), even at extremely low levels, can cause severe health effects in a percentage of those exposed; consequently, occupational exposure limits (OELs) promulgated for this element are the lowest established for any element. This work describes the advantages of using highly alkaline dye solutions for determination of Be in occupational hygiene and environmental samples by means of an optical molecular fluorescence technique after sample extraction in 1–3% (w?w^?1) aqueous ammonium bifluoride (NH₄HF₂). Improved attributes include the ability to further enhance the detection limits of Be in extraction solutions of high acidity with minimal dilution, which is particularly beneficial when NH₄HF₂ solutions of higher concentration are used for extraction of Be from soil samples. Significant improvements in Be method detection limits (MDLs) are obtained at levels manyfold below those reported previously for this methodology. Notably, MDLs for Be of <0.01 ng L^?1 /0.1 ng per sample have been attained, which are superior to MDLs routinely reported for this element by means of the most widely used ultra-trace elemental measurement technique, inductively coupled plasma mass spectrometry (ICP-MS). Very low MDLs for Be are essential in consideration of reductions in OELs for this element in workplace air by health organisations and regulatory agencies in the USA and internationally. Applications of enhanced Be measurements to air filter samples, surface wipe samples, soils and newly designed occupational air sampler inserts are illustrated.     

铝中超微量铀的ICP-MS测定

采用多接收电感耦合等离子体质谱（ICP-MS）对铝锭及氧化铝中的超微量铀进行了分析测定,采用浓盐酸溶解样品,监测流程空白.未对铝基体进行分离,直接进行分析测定,相对标准偏差小于4%.     

High-Quality Conjugated Polymers Achieving Ultra-Trace Detection of Cr2O72− in Agricultural Products

In view of that conjugated polymers (CPs) are an attractive option for constructing high-sensitive Cr₂O₇²⁻ sensors but suffer from lacking a general design strategy, we first proposed a rational structure design of CPs to tailor their sensing properties while validating the structure-to-performance correlation. Short side chains decorated with N and O atoms as recognition groups were instructed into fluorene to obtain monomers Fmoc-Ala-OH and Fmoc-Thr-OH. Additionally, their polymers P(Fmoc-Ala-OH) and P(Fmoc-Thr-OH) were obtained through electrochemical polymerization. P(Fmoc-Ala-OH) and P(Fmoc-Thr-OH) with high polymerization degrees have an excellent selectivity towards Cr₂O₇²⁻ in comparison to other cations and anions. Additionally, their limit of detection could achieve 1.98 fM and 3.72 fM, respectively. Especially, they could realize the trace detection of Cr₂O₇²⁻ in agricultural products (red bean, black bean, and millet). All these results indicate that short side chains decorated with N and O atoms functionalizing polyfluorene enables the ultra-trace detection of Cr₂O₇²⁻. Additionally, the design strategy will spark new ideas for the construction of highly selective and sensitive Cr₂O₇²⁻ sensors.     

Resonance Ionization Mass Spectrometry (RIMS) with Pulsed and CW-Lasers on Plutonium

The detection of long-lived plutonium isotopes in ultra-trace amounts by resonance ionization mass spectrometry (RIMS) is a well-established routine method. Detection limits of 10⁶ to 10⁷ atoms and precise measurements of the isotopic composition have been achieved. In this work multi-step resonance ionization of plutonium atoms has been performed with tunable lasers having very different output intensities and spectral properties. In order to compare different ways for the resonance ionization of plutonium broadband pulsed dye and titanium:sapphire lasers as well as narrow-band cw-diode and titanium:sapphire lasers have been applied for a number of efficient excitation schemes. It has been shown, that for identical excitation schemes the optical isotope selectivity can be improved by using cw-lasers (bandwidths < 10 MHz) instead of pulsed lasers (bandwidths > 2 GHz). Pulsed and cw-laser systems have been used simultaneously for resonance ionization enabling direct comparisons of pulsed and continuous ionization processes. So far, a three-step, three-color laser excitation scheme has been proven to be most practical in terms of efficiency, selectivity and laser wavelengths. Alternatively a newly discovered three-step, two-color excitation scheme which includes a strong two-photon transition from an excited state into a high-lying autoionizing state yields similar ionization efficiencies. This two-photon transition was characterized with respect to saturation behavior and line width.     

超声波-微分脉冲伏安法测定超痕量铜

以循环伏安和微分脉冲伏安法研究了超声作用下铜在铂电极上的电沉积行为,建立了超痕量铜的超声波-微分脉冲伏安法。超声波增加了铜的阳极溶出峰电流近一个数量级,提高了方法的灵敏度。在优化实验条件下,铜的微分脉冲阳极溶出峰电流与铜离子浓度在两个范围内呈线性关系。在5.00~200nmol/L的浓度范围内,线性方程为I=0.0453 0.00101c(nmol/L,R=0.9963,SD=0.0078);检出限为0·20nmol/L(13ng/L);在0.200~8.00μmol/L浓度范围内,线性方程为i=0.243 0.0864c(μmol/L,R=0·9983,SD=0.0188)。常见金属离子一般不干扰。方法简便快速,直接用于自来水实际样品的测定,加标回收率为95.4%~104.6%;RSD为3.36%,结果令人满意。     

运用金-银核壳结构纳米棒的表面增强拉曼效应检测超痕量葡萄糖

运用种子生长法合成金纳米棒溶胶,再经过化学还原法合成金-银核壳纳米棒溶胶作为表面增强拉曼活性基底。该基底可以检测低至10-18mol/L的罗丹明6G,其增强因子高达1011,具有优异的SERS增强效果。利用此基底的表面增强拉曼散射效应检测10-14~10-8mol/L的葡萄糖,并得到表面增强拉曼信号强度与相应葡萄糖浓度的工作曲线。实验结果表明,该基底在葡萄糖的检测及半定量分析方面具有良好的潜在应用前景。     

在线固相萃取-超高效液相色谱-串联质谱法快速测定地表水中超痕量阿特拉津

建立了在线固相萃取-超高效液相色谱-串联质谱（on line SPE-UPLC-MS/MS）测定地表水中超痕量阿特拉津的方法。样品经滤膜过滤,HLB Direct Connect HP在线固相萃取小柱富集纯化,甲醇溶液洗脱,以Acquity BEH 130为分析柱,串联质谱进行检测,外标法定量。阿特拉津在1.0~5000 ng/L范围内线性关系良好,相关系数（r）为0.9989;该方法检出限为0.2 ng/L,阿特拉津的回收率为83.0%~105.1%,相对标准偏差为1.6%~5.3%（n=7）,满足超痕量分析测试的要求。该法灵敏度高,分析速度快,对于保障水环境安全、及时提供污染信息、有效应对环境应急突发事件具有十分重要的意义。