高效液相色谱-电感耦合等离子体质谱法测定面粉中溴酸盐与溴化物

建立了高效液相色谱-电感耦合等离子体质谱(HPLC-ICPMS)联用技术测定面粉样品中BrO-3与Br-的方法.采用ICS-A23色谱柱分离溴形态,以30 mmol/L (NH4)2CO3为流动相,pH 8,流速0.8 mL/min,进样量1.0 mL.在此条件下,BrO-3与Br-的方法检出限(以溴计)分别为0.052 和0.048 μg/L.可满足面粉样品中痕量溴形态的测定.对3种不同样品前处理方法(超声法、水浴法以及振荡水提法)进行了比较,最终确定振荡水提1 h为面粉样品的前处理方法,其形态加标回收率为93%～111%,且各形态溴量之和与标准值基本一致,均在标准值的允许误差范围之内.利用本方法对市售10种面粉样品中的溴形态进行了测定,所测样品中均未检出BrO-3.     

高效液相色谱-电感耦合等离子体质谱法测定紫菜中的碘形态

建立了高效液相色谱-电感耦合等离子体质谱(HPLC-ICP-MS)联用技术测定紫菜中IO_3~-,I~-,MIT和DIT的方法。采用离子交换色谱柱AS7分离4种碘形态,以175 mmol/L NH_4NO_3和4%(V/V)甲醇为流动相,在梯度洗脱的条件下可实现4种碘形态的完全分离。在此条件下,IO_3~-,I~-,MIT和DIT的方法检出限(以碘计)分别为0.09,0.34,0.09,0.33μg/L,可满足紫菜中碘形态的测定要求。对紫菜样品前处理方法进行了优化比较,最终确定40℃超声提取2次,每次超声2 h为紫菜样品前处理方法,方法可保持样品处理过程中各碘形态的稳定。利用建立的方法并结合体积排阻色谱对紫菜标准物质GSB-14中的碘形态进行分析,发现其主要以I~-和一种未知碘形态存在。     

IO3--I--丁基罗丹明B体系测定面粉中痕量溴酸根

在磷酸介质中,BrO3-氧化I-形成I3-络阴离子,I3-络阴离子可进一步与丁基罗丹明B阳离子形成离子缔合物,在聚乙烯醇存在下,缔合物呈清亮的紫色溶液,以试剂空白为参比,最大吸收波长位于587nm,吸光度A与BrO3-浓度呈线性关系。线性范围0.20～3.50μg/10mL,表观摩尔吸光系数为9.79×104L·mol-1.cm-1,检出限为0.012μg·mL-1,样品回收率94.0%～100.3%,RSD为2.81%。该方法用于面粉中痕量溴酸根测定,结果令人满意。     

控温超声提取-气相色谱-三重四级杆质谱测定大气细颗粒物(PM2.5)中的多环芳烃

建立了控温超声提取-气相色谱三重四级杆质谱测定大气细颗粒物(PM2.5)中多环芳烃(Polycyclic aromatic hydrocarbon,PAHs)的分析方法。PM2.5中的PAHs用二氯甲烷-正己烷(2∶1,V/V)控温超声提取3次,每次提取20 min,气相色谱-串联质谱分析,得到16种PAHs和6种替代物的标准曲线线性关系良好,相关系数均大于0.99,16种PAHs的检出限范围为0.013~0.12μg/L。实验中还观察到PAHs在空白滤膜中有微量存在,回收率实验中得到6种替代物的回收率在58.7%~108.2%之间,16种PAHs的空白滤膜加标的平均回收率在88.3%~104.0%之间,相对标准偏差均低于9.0%,实际滤膜加标的平均回收率在77.3%~98.7%之间,相对标准偏差均低于6.0%,本方法能够满足实际大气样品的测定。     

测定大气颗粒物中金属含量的样品预处理

通过综合对比实验，从多种样品预处理方法中筛选出测定大气颗粒物中金属含量的样品预处理方法——HNO3-HClO4热消解提取法。该法操作简便、易于掌握，待测金属及其化合物提取率达90%以上（滤筒样品84%以上），而且空白值低，可与化学法及仪器法配套使用。     

离子法测定高氯气田水中的氯离子及其他痕量无机阴离子

 研究了高氯气田水样中的Cl-及痕量F-,Br-,I-和SO42 -的离子分析方法。选择的条件为 :亲水性较强的IonPacAS11阴离子交换分离柱分离 ,氢氧化钠梯度淋洗 ,自动再生抑制型电导检测。样品通过 0 4 5 μm微孔滤膜过滤和DionexOnGuardRPC18反相小柱处理。方法具有良好的线性 (相关系数在 0 9994～ 0 9999)和重复性 (相对标准偏差小于 3 3% ) ,加标平均回收率在 98 4 %～ 10 2 1%。方法简便实用 ,用于实际样品分析 ,所得结果令人满意。     

气溶胶、降水中的有机酸、甲磺酸及无机阴离子的离子色谱同时快速测定法

建立了梯度淋洗 ,在14min内同时测定大气气溶胶和降水中的甲酸、乙酸、草酸及大气中海洋微生物硫释放源指示物甲磺酸 (MSA)与无机阴离子F -、Cl-、 2-NO、 3-NO、 42-SO 、 3-4PO 的新方法 ;线性回归系数达0.9983～0.9998 ,分离度7.260 ,相对标准偏差在5 %以下 ,检出限(S/N=3)达1×10-8 (w) ,样品的加标回收率为80 %～120 % ;确定了不同滤膜采集的气溶胶的最佳浸提条件以及最佳色谱分离操作条件 ;此法已有效地应用于我国实地采集的气溶胶和降水的组分分析。     

针头式滤器水溶出物对样品分析的影响

滤膜材质分别为混合纤维素酯、尼龙、聚四氟乙烯、聚偏氟乙烯、聚醚砜的针头式滤器经去离子水过滤后有溶出物,对样品中F-、Cl-、SO2-4、Br-或NO-3等阴离子的分析可产生显著影响,另有组分可干扰样品的脉冲安培检测。采用电喷雾质谱或气相色谱-质谱能检出混合纤维素酯针头式滤器溶出物中的添加剂成分。对不同品牌及滤膜材质针头式滤器水溶出物的定量分析结果表明,F-、Cl-、SO2-4浓度多在10μg/L以上。针头式滤器对所滤样品的影响不容小觑,亟需相关标准来规范针头式滤器的质量。     

大气颗粒物中有机物色谱分析的样品制备技术

大气颗粒物中有机物成分分析对深入研究大气颗粒物对人类健康、环境、气候、生态的影响,解析气溶胶来源,制定颗粒物控制相关法规,以及风险管理方法具有重要意义。由于颗粒物中的有机组分种类繁多,分析复杂,目前仅10%~20%的有机物得到了定性和定量分析。因此,大气细颗粒中有机物的分析已成为环境分析领域的优先发展方向。色谱是大气颗粒物中有机物分析的主要方法,而样品制备则是影响分析速度和精度的关键步骤。本文对颗粒物中有机组分色谱分析前的样品制备方法进行了综述,介绍了索氏提取、超声辅助提取、微波辅助提取、加压溶剂提取等溶剂提取方法以及热解吸提取方法,并重点介绍了这些方法在大气颗粒物样品处理中的应用,总结了各种方法的优缺点。     

响应面分析法和单因素分析法优化艾草中黄酮类物质的提取条件

选择分子荧光光度法对艾草中黄酮类物质的提取条件的优化试验试液中的黄酮类物质进行测定,从而算得不同条件下所达到的提取率以确定最佳的提取条件。研究了提取过程中的三因素:乙醇溶液体积分数、超声时间和艾草质量与乙醇溶液体积的比值。并按单因素分析法测得提取过程中3项因素最佳参数分别为:乙醇溶液的体积分数为50%,超声提取的时间为40min,艾草样品和50%乙醇溶液的比值为1.0g比15 mL。在此条件下,艾草中黄酮类物质的提取率为1.07%。以上述3项因素作为响应面分析法的优化因素,利用Design Expert 8.0软件进行三因素三水平的析因试验,对此提取条件作进一步的优化,得到了最佳的提取条件为:①乙醇溶液的体积分数为49.96%;②超声提取时间为30min;③艾草样品与50%乙醇溶液的比值为0.79g比15mL。在此条件下提取率可达1.09%。按此条件称取艾草粉末样品0.790 0g(3份),分别按上述优化的条件进行超声提取后,经过滤并离心后取其上清液(分取量应按样品中黄酮类物质的估计含量决定,使其量落在标准曲线的线性范围0.006～0.018g·L-1之间)1mL,依次加入5.3g·L-1硝酸铝溶液2.38 mL和乙酸盐缓冲溶液(pH 5.6)0.9 mL后,加入50%乙醇溶液将其体积定容至10.0mL。待黄酮类物质与铝(Ⅲ)离子的荧光配位反应完全后,测定其荧光发射强度。此3份样品的黄酮类物质平均提取率为1.08%,与理论预测值的相对误差为-0.92%。     

Determination of iodine and bromine compounds in foodstuffs by CE-inductively coupled plasma MS

A CE-inductively coupled plasma mass spectrometric (CE-ICP-MS) method for iodine and bromine speciation analysis is described. Samples containing ionic iodine (I(-) and IO(3)(-)) and bromine (Br(-) and BrO(3)(-)) species are subjected to electrophoretic separation before injection into the microconcentric nebulizer (CEI-100). The separation has been achieved in a 50 cm length x 75 microm id fused-silica capillary. The electrophoretic buffer used is 10 mmol/L Tris (pH 8.0), while the applied voltage is set at -8 kV. Detection limits are 1 and 20-50 ng/mL for various I and Br compounds, respectively, based on peak height. The RSD of the peak areas for seven injections of 0.1 microg/mL I(-), IO(3)(-) and 1 microg/mL Br(-), BrO(3)(-) mixture is in the range of 3-5%. This method has been applied to determine various iodine and bromine species in NIST SRM 1573a Tomato Leaves reference material and a salt and seaweed samples obtained locally. A microwave-assisted extraction method is used for the extraction of these compounds. Over 87% of the total iodine and 83% of the total bromine are extracted using a 10% m/v tetramethylammonium hydroxide (TMAH) solution in a focused microwave field within a period of 10 min. The spike recoveries are in the range of 94-105% for all the determinations. The major species of iodine and bromine in tomato leaves, salt, and seaweed are Br(-), IO(3)(-), I(-), and Br(-), respectively.     

Determination of halogen species of humic substances using HPLC/ICP-MS coupling

A mass spectrometric method for the determination of chlorine, bromine and iodine species of humic substances (HS) has been developed by coupling a HPLC system with ICP-MS. Using size exclusion chromatography, the method was applied to the characterization of natural water samples (ground water, seepage water from soil, brown water) and a sewage water sample. Quantification of iodine/HS species was carried out by the on-line isotope dilution technique, which was not possible for bromine and chlorine species because of mass spectroscopic interferences by using a quadrupole ICP-MS. Characteristic fingerprints of the halogen/HS species, correlated with the corresponding UV chromatogram, were obtained dependent on the different origin of HS. Biological influences were indicated when following changes of the iodine/HS species composition by aging. The formation of iodine/HS species from inorganic iodide was investigated by labelling experiments with an ¹²⁹I^– spike solution, resulting in the finding that specific HS fractions are preferably iodinated.     

Determination of the total amount of organically bound chlorine,bromine and iodine in environmental samples by instrumental neutron activation analysis

The determination of chlorine, bromine and iodine present as non-polar, hydrophobic hydrocarbons in environmental samples is reported. The organohalogen compounds are separated from water into an organic phase by on-site liquid—liquid extraction, and from biological material by procedures based on lipid phase extraction and codistillation. After removal of inorganic halides by washing with water and concentration of the sample by evaporation of the solvent, the resulting extracts are analyzed for their chlorine, bromine and iodine contents by instrumental neutron activation analysis. Strict attention is paid to the possibility of contamination in every step of the procedure. Background values in routine analysis are approximately 100–200 ng of chlorine, <5 ng of bromine and <3 ng of iodine.     

The collection and determination of atmospheric gaseous bromine and iodine

A procedure has been developed which allows for the isolation, collection and analysis of atmospheric gaseous iodine and bromine. Particulate matter is removed from the airstream to be sampled by electrostatic precipitation. The gaseous halogen species are adsorbed onto specially cleaned activated charcoal. After irradiation of the charcoal sample with thermal neutrons, the iodine and bromine are removed from the charcoal, isolated, and purified as the AgX precipitate. The amounts of gaseous iodine and bromine are then determined by β-counting. The system works well for air sheds with low particulate iodine and bromine concentrations relative to that in the gaseous phase. In air sheds where the particulate halogen predominates, the gas phase measurements are more uncertain.     

Use of neutron activation analysis in determination of total organic chlorine and bromine

Neutron activation analysis is practically the only high-sensitivy element-selective detection method for chlorine, bromine and iodine. This method is just ideal for organic halogen determination after separation of organically bound species from inorganic. In recent years we have analysed organic chlorine and bromine from thousands of different kind of samples with different separation methods. For water samples we have used activated-carbon adsorption and for solid samples mostly propanone or combined alkaline/propanone extraction before activated-carbon adsorption. Inorganic chlorides were removed from the carbon by nitrate wash. The detection limits for total organic chlorine and bromine are 5 and 0.5 g/l for water (sample size 100 ml) and 0.3 and 0.1 g/g dry weight (sample size 1 g) for sediment.     

Contribution of milk to daily intakes of iodine and bromine in northwestern Ukraine

Summary The concentration of stable iodine and bromine in Ukrainian milk has been determined in relation to the effect of the Chernobyl nuclear power plant accident. The geometric mean of iodine and bromine concentration was 31.0mg/kg and 2.57 mg/kg, respectively. Compared with Japanese milk, it was statistically lower. Bromine concentrations in Ukrainian and Japanese milk were not significantly different. Contribution of milk to daily intake of iodine and bromine in Ukrainian adults has been estimated to 88% and 94%.     

Determination of iodine and bromine in plasma and urine by inductively coupled plasma mass spectrometry

The simultaneous determination of iodine and bromine in plasma and urine by inductively coupled plasma mass spectrometry, using a Nermag prototype instrument, is described. The sample preparation involves only a 10-fold dilution with a diluent containing europium as an internal standard followed by direct nebulisation in the plasma. The iodine, bromine and europium ions are measured at m/z = 127, 79, and 153, respectively. The sensitivity of the method, with detection limits of 1.6 and 52 micrograms l-1 for iodine and bromine, respectively, is satisfactory for clinical applications. The calibration graphs were linear over the ranges 0-400 micrograms l-1 and 0-40 mg l-1 for iodine and bromine, respectively, which are wide enough for most assays. The recoveries were close to 100% with coefficients of variation of less than 3%. The within-day and between-day reproducibility was about 5%. The concentrations of iodine and bromine in the plasma of 26 healthy individuals were 58 +/- 12 micrograms l-1 and 4.1 +/- 0.9 mg l-1, respectively. The amounts of iodine and bromine eliminated in urine were 94 +/- 97 micrograms per 24 h (range 27-403 micrograms per 24 h) and 3.6 +/- 1.7 mg per 24 h, respectively. These results are in agreement with reported values.     

Relationship between dye–iodine binding and cell voltage in dye‐sensitized solar cells: A quantum‐mechanical look

It has been proposed that iodine binding to dyes may actually decrease the cell efficiency of a dye‐sensitized solar cell. A previous experimental study showed that a two‐atom change from oxygen to sulfur increased recombination of iodine with injected electrons by a factor of approximately 2. Here, it is shown that iodine binding is a plausible explanation for this effect. The steric and conjugation effects are quantified separately using a set of model compounds. Quantum‐chemical calculations show that elongation of the hydrocarbon chain has only an insignificant effect on the iodine and bromine binding to the chalcogen atoms (O, S, Se). The conjugation, however, significantly disfavors the iodine and bromine interaction. Iodine and bromine binding to the dye and model compounds containing sulfur is significantly more favorable than to their oxygen containing counterparts. Bromine binding to dyes is shown to be stronger than that of iodine. Accordingly, bromine binding to dyes may contribute significantly to the observed lower efficiencies in cells using Br/Br^? as the redox couple. © 2012 Wiley Periodicals, Inc.     

Speciation analysis of iodine and bromine at picogram-per-gram levels in polar ice

Iodine and bromine species participate in key atmospheric reactions including the formation of cloud condensation nuclei and ozone depletion. We present a novel method coupling a high-performance liquid chromatography with ion chromatography and inductively coupled plasma mass spectrometry, which allows the determination of iodine (I) and bromine (Br) species (IO ₃ ^? , I^?, Br^?, BrO ₃ ^? ) at the picogram-per-gram levels presents in Antarctic ice. Chromatographic separation was achieved using an IONPAC® AS16 Analytical Column with NaOH as eluent. Detection limits for I and Br species were 5 to 9 pg g^?1 with an uncertainty of less than 2.5% for all considered species. Inorganic iodine and bromine species have been determined in Antarctic ice core samples, with concentrations close to the detection limits for iodine species, and approximately 150 pg g^?1 for Br^?. Although iodate (IO ₃ ^? ) is the most abundant iodine species in the atmosphere, only the much rarer iodide (I^?) species was present in Antarctic Holocene ice. Bromine was found to be present in Antarctic ice as Br^?.     

The synthesis of fluoroether-fluorosilicone hybrid polymers

The replacement of the fluorocarbon segment in the general class of hybrid fluorocarbon-fluorosilicones by fluoroether units was investigated in order to improve low temperature properties without sacrificing high temperature performance. The effects of the co-reactant halogens (bromine and iodine) and metallic fluorides (potassium fluoride and cesium fluoride) on the product yields in the syntheses of the requisite α,ω-dihalo-F-ether intermediates [1] from the corresponding acyl or diacyl fluorides were studied. While a better yield was obtained with bromine than with iodine, the iodoperfluoroethers produced superior yields in the subsequent ethylene addition reactions, as expected. Potassium fluoride was preferable to cesium fluoride in the synthesis of the iodo-F-ethers, since cesium fluoride effects decomposition of the ethers.