预富集单波长激发能量色散X射线荧光光谱法现场测定地表水中10种重金属

为实现现场快速定量分析地表水中的多种重金属元素,建立了一种树脂预富集-单波长激发能量色散X射线荧光光谱法现场准确快速测定地表水中Cr(Ⅵ)、Mn、Fe、Co、Ni、Cu、Zn、As、Cd、Pb 10种元素的分析方法。对该方法其中的树脂预富集条件进行了优化,结果表明最佳预富集条件为：树脂粒度38μm-75μm;水样体积30mL;水样流速6mL/min;预富集完成后即刻测量;样品pH值为5。在方法学方面考察了该方法的检出限、精密度、正确度,其中Cr(Ⅵ)、Cu、Zn、As、Cd、Pb 元素的检出限低于地表水环境质量标准GB 3838-2002的限值要求;精密度中相对标准偏差范围为2.13%~10.4%;加标回收率为90.0%~114%之间。采用该方法测定实际地表水样品,并与ICP-MS法进行比对,其测定结果基本一致。研究表明该方法检出限可以满足地表水中Cr(Ⅵ)、Mn、Fe、Co、Ni、Cu、Zn、As、Cd、Pb 的检测要求,精密度和准确性较好。该研究对地表水中无机元素分析方法的拓展进行了有益尝试和积累,并为后续相关标准制订提供有益参考。     

酸洗污泥与煤共燃烧过程中重金属的迁移分布研究

采用高温管式炉系统进行酸洗污泥与煤共燃烧实验。对共燃烧后As、Cr、Ni、Cd、Cu、Mn、Pb、Zn、Sb、Se重金属元素在烟气、飞灰及炉渣中的分配率进行分析。结果表明,Cd、Se、Zn是易挥发重金属,主要分布在烟气和飞灰中。Cd在烟气中的最大分配率为61%;Se在烟气中的分配率为38.58%~94.612%;Zn在低、高温段分别主要分布在烟气和飞灰中。As、Cu、Pb、Sb是半挥发重金属,Pb在炉渣中的分配率较稳定,分配率为42.67%~64.76%,在烟气和飞灰中的分配率波动较大,其分配率分别是14.176%~45.79%和9.78%~32.55%;Sb在烟气中的最大分配率为37.64%;温度升高反而会抑制As、Cu挥发,这与高温下As、Cu易与矿物质反应生成络合物有关。Ni、Cr、Mn属于难挥发重金属,绝大部分残留在炉渣中,且分配率对温度变化不敏感。赋存于炉渣中的Cr、Ni分别超过95%和97%;随着温度升高,Mn在炉渣中的分配率由71.46%增加到96.89%。     

黄原脂棉富集-电感耦合等离子质谱法测定海水中的重金属元素

采用黄原脂棉富集技术,建立了电感耦合等离子质谱法测定海水中重金属Cu,Pb,Zn,Co,Cd含量的方法。完善前处理条件,优化仪器工作参数,选取Rh,Ir作为内标元素,有效克服基体效应及仪器波动影响。Cu,Pb,Zn,Co,Cd的检出限分别为1.26,0.21,0.24,0.0027,0.0051μg/L,RSD为0.77%~3.3%,回收率为87.2%~96.0%。方法适用于海水中重金属元素的含量测定。     

微波消解-电感耦合等离体子质谱法(ICP-MS)同时测定畜禽粪便中7种重金属元素

粪便样品干燥、研磨后,称取0.25 g样品,加入8 mL硝酸,采用微波消解方法进行前处理。采用KED模式消除质谱干扰,采用内标校正消除非质谱干扰(Ge作为Cu、Zn、Cr的内标,Bi作为Hg和Pb的内标,Rh作为As和Cd的内标),建立了可同时测定畜禽粪便中Cu、Zn、Cr、As、Cd、Pb、Hg 7种重金属元素的微波消解-电感耦合等离子体质谱法。方法线性相关系数均在0.9995以上,检出限为0.005~0.305μg/L,加标回收率为83.6%~112%,相对标准偏差为0.70%~5.6%。方法灵敏度、准确度和精密度高,实用性强,适用于同时检测畜禽粪便中多种重金属元素,对畜禽粪便的科学还田具有指导意义。     

不同消解方法分析污泥中重金属含量的比较

采用三种电热板消解体系和两种微波消解体系分别对两种类型的污泥进行消解,并以电感耦合等离子体发射光谱法测定其中的Cu、Pb、Cr、Cd、Ni、Zn等11种金属的含量.结果表明,H2O2-王水-HF微波消解体系可实现污泥中重金属的充分溶解,对样品中Cu、Pb、Cr、Ni回收率可达96%~104%,相对标准偏差为0.16%~3.48%.该方法具有精密度好、准确度高、耗酸量少、操作安全简便等优点,适用于污泥中重金属的分析测定.     

ICP-AES法测定滑子蘑中的Cd、Cu、Pb和Zn

建立了采用V(HNO3)∶V(HClO4)=15∶2作消解液进行溶样,ICP-AES法同时测定滑子蘑中Cd、Cu、Pb、Zn的分析方法,进行了ICP工作参数的优化,消解条件的选择及消解结果精密度实验。在最佳测定条件下,4种元素标准曲线相关性好(r为0.9990~0.9995),线性范围宽,精密度RSD为0.4%~4.6%,样品加标回收率为91.0%~101.0%,已用于实际样品的测定。     

微波消解-火焰原子吸收光谱法测定紫菜中八种微量元素

采用微波消解紫菜样品,用火焰原子吸收光谱法测定了样品中Fe、Mg、Zn、Ca、Pb、Cd、Mn、Cu的含量。结果表明,该法具有良好的准确度和精密度,加标回收率在97.0%~102.2%范围内,相对标准偏差(RSD)≤1.82%,为研究金属元素在紫菜中的含量与食疗保健功效的关系提供了有用的数据。     

基于全反射X射线荧光光谱测定污水痕量重金属元素

以Ga为内标,探究全反射X射线荧光光谱（TXRF）快速测定多质量梯度浓度多元素重金属溶液Mn、Fe、Co、Ni、Cu、Zn、As、Cd、Sn、Sb和Pb的可行性,并以实际生活污水为研究对象,比较分析了离心、过滤和消解3种预处理方式对测定污水中重金属元素的影响。实验结果表明,Mn、Fe、Co、Ni、Cu、Zn、As和Pb,较适宜用TXRF直接进行定量分析;Pb的Lα与As的Kα谱线重叠,致使As的回收率略高于其它元素;Cd、Sn和Sb元素,仅可用于趋势分析。当质量浓度为40和4 mg/L时,Mn、Fe、Co、Ni、Cu、Zn和Pb元素呈现出较高的准确度和精密度,回收率在99%～117%之间,相对标准偏差（RSD）处于1%～14%。随着质量浓度的逐渐降低,各元素的准确度和精密度表现出不同程度的下降,当质量浓度处于本次试验的最低水平4μg/L时,大部分元素的回收率与RSD已超出定量分析的要求。通过对生活污水的3种预处理方式进行比较,发现污水悬浮颗粒同样携带部分金属元素,经消解后,Mn、Fe、Co、Ni、Cu和Zn这6种元素的准确度和精密度最好,质量浓度范围在36～152μg/L之间,回收率均...     

六极杆碰撞反应池–ICP–MS法测定海水中痕量金属元素

建立了直接稀释法测定海水中痕量金属元素Cr,Cu,Zn,Cd,Pb的方法。样品经稀释10倍后,使用基体匹配及内标校正,采用六极杆碰撞反应池–电感耦合等离子体质谱仪直接测定稀释后海水样品中的5种元素Cr,Cu,Zn,Cd,Pb。各元素在0.0~100μg/L范围内均呈现良好的线性关系,线性相关系数(r~2)均大于0.999 0,方法检出限为0.004~0.209μg/L。测定结果的相对标准偏差为2.4%~4.4%(n=6),加标回收率为92%~113%。该方法简单快捷,适用于近岸海水中痕量元素Cr,Cu,Zn,Cd,Pb的分析。     

电感耦合等离子体原子发射光谱（ICP-AES）法测定 高纯氧化铟中7种杂质元素

采用电感耦合等离子体原子发射光谱(ICP-AES)法测定高纯氧化铟中杂质元素Al、Cd、Cu 、Fe、Pb、Tl和Zn等的含量。使用盐酸(1+1)溶解高纯氧化铟试样,基体铟的干扰采用基体匹配法消除,被测元素之间没有光谱干扰。对方法进行加标回收实验和精密度实验,方法加标回收率在92.2%~110%之间,测得结果的相对标准偏差在0.57%~5.8%之间。     

ICP-AES法测定锌阳极中的铝、镉、铁、铜、铅

通过分析高频功率、雾化压力、辅助气流量和泵速等试验条件，建立了ICP-AES法测定锌阳极中铝、镉、铁、铜、铅的方法。用该方法测定锌阳极中的铝、镉、铁、铜、铅，其RSD分别为0.17%、0.63%、2.7%、5.2%、2.5%，回收率分别为99.3%-101.2%，99.3%-100.3%、97.1%-102.2%、97.8%-102.9%。对锌阳极试样进行测定，该方法的测定结果与GB4951-85方法的测定结果基本一致。     

Determination of Co, Cu, Fe, Ga, W, and Zn in rocks by neutron activation and anion-exchange separation

A neutron-activation method for the simultaneous determination of cobalt, copper, gallium, iron, tungsten and zinc in rocks is described. The method is based on anion-excbange separation in hydrochloric acid media. Chemical yield is higher than 97% for all elements, except for tungsten, where the recovery of the carrier is established by re-activation. The precision is about 1-3% for the iron determination and about 3% for cobalt, copper, gallium and zinc.     

微波灰化/DUO-ICP-AES测定残渣燃料油中的铝、硅、钒

采用微波灰化技术消解残渣燃料油,用全谱直读DUO-ICP-AES同时测定残渣燃料油中的铝、硅、钒,优化了仪器工作参数和实验条件.结果表明,在质量浓度0 ～25.0 mg/L范围内铝、硅、钒的线性关系良好(r=0.999 70 ～0.999 99),检出限、回收率和相对标准偏差分别为0.005 ～0.050 mg/L、8...     

Enzymatic resolution, desymmetrization, and dynamic kinetic asymmetric transformation of 1,3-cycloalkanediols

An efficient desymmetrization of cis-1,3-cyclohexanediol to (1S,3R)-3-(acetoxy)-1-cyclohexanol ((R,S)-2a) was performed via Candida antarctica lipase B (CALB)-catalyzed transesterification, in high yield (up to 93%) and excellent enantioselectivity (ee's up to >99.5%). (R,R)-Diacetate ((R,R)-3a) was obtained in a DYKAT process at room temperature from (1S,3R)-3-acetoxy-1-cyclohexanol ((R,S)-2a), in a high trans/cis ratio (91:9) and in excellent enantioselectivity of >99%. Metal- and enzyme-catalyzed dynamic transformation of cis/trans-1,3-cyclohexanediol using PS-C gave a high diastereoselectivity for cis-diacetate (cis/trans = 97:3). The (1R,3S)-3-acetoxy-1-cyclohexanol (ent-(R,S)-2a) was obtained from cis-diacetate by CALB-catalyzed hydrolysis in an excellent yield (97%) and selectivity (>99% ee). By deuterium labeling it was shown that intramolecular acyl migration does not occur in the transformation of cis-monoacetate to the cis-diacetate.     

8-Alkenylborondipyrromethene dyes. General synthesis, optical properties, and preliminary study of their reactivity

A new series of 8-alkenylBODIPY dyes were prepared via the Liebeskind-Srogl cross-coupling starting from 8-thiomethyl-substituted BODIPY. Ten derivatives were prepared using alkenylboronic acids in good to excellent yields (79-97%), and one additional example was prepared from an alkenylstannane in 74% yield. The products display Michael acceptor-like reactivity. The alkenyl fragment quenches the fluorescence of the BODIPY core, which is turned back on by reducing the double bond.     

Indirect potentiometric determination of hydrazine, isoniazid, sulphide and thiosulphate with a chloramine-T ion-selective electrode

Indirect potentiometric procedures with chloramine-T (CAT) as the oxidant and a chloramine-T ion-selective electrode are described for the determination of hydrazine and isonicotinic acid hydrazide (isoniazid) in the 1-100 mumole range and of sulphide and thiosulphate in the 0.5-50 mumole range. The reductants react stoichiometrically with a known and excessive volume of added CAT and the unconsumed excess of CAT is measured with the CAT-selective electrode. Aqueous solutions of the reductants were analysed with an error and precision of about 1-2%. Analytical recovery of isoniazid added to tablet diluents was 97-101% (average 98.9%). Results were comparable with those obtained with a titrimetric method for the determination of isoniazid in injection solutions and tablets.     

Selective N-debenzylation of benzylamino derivatives of 1, 6-anhydro-beta-D-hexopyranoses

When the series of 2-, 3-, and 4-(benzylamino)-2-, 3-, and 4-deoxy derivatives of 1,6-anhydro-beta-D-hexopyranoses in the D-gluco, D-lyxo, and D-arabino configurations were reacted with diisopropyl azodicarboxylate, N-benzyl groups were selectively cleaved in the presence of O-benzyl groups. The yields ranged from 51 to 97%. The debenzylation of some aliphatic benzylamines is also discussed.     

An evaluation of analytical techniques for determination of lead, cadmium, chromium, and mercury in food-packaging materials

Closed microwave digestion and a high-pressure asher have been evaluated for wet-oxidation and extraction of lead, cadmium, chromium, and mercury from a range of typical packaging materials used for food products. For the high-pressure asher a combination of nitric and sulfuric acids was efficient for destruction of a range of packaging materials; for polystyrene, however, nitric acid alone was more efficient. For microwave digestion, a reagent containing nitric acid, sulfuric acid, and hydrogen peroxide was used for all materials except polystyrene. Use of the high-pressure asher resulted in the highest recoveries of spiked lead (median 92%), cadmium (median 92%), chromium (median 97%), and mercury (median 83%). All samples were spiked before digestion with 40 microg L(-1) Cd, Cr, and Pb and 8 microg L(-1) Hg in solution. The use of indium as internal standard improved the accuracy of results from both ICP-MS and ICP-AES. Average recovery of the four elements from spiked packaging materials was 92 +/- 14% by ICP-MS and 87 +/- 15% (except for mercury) by ICP-AES. For mercury analysis by CVAAS, use of tin(II) chloride as reducing agent resulted in considerably better accuracy than use of sodium borohydride reagent.     

Application of shielded column liquid chromatography for determination of sulfamonomethoxine, sulfadimethoxine, and their N4-acetyl metabolites in milk

A hazardous-chemical free method for simultaneous determination of sulfamonomethoxine (SMM), sulfadimethoxine (SDM), and their N4-acetyl metabolites in raw milk using shielded column liquid chromatography is developed. The target analytes are extracted by mixing with ethanol-acetic acid (97:3, v/v) followed by centrifugation. The procedure uses a Hisep shielded hydrophobic phase (SHP) column, isocratic elution with 0.1% acetic acid solution (pH 3.1, in water)-ethanol (75:25, v/v), and a photo-diode array detector. Average recoveries from samples spiked at 25-500 ng/ml for each drug were >81% with relative standard deviations within 5%. The limits of quantitation were <25 ng/ml.     

Extraction of palladium from nitric acid medium by commercial resins with phosphinic acid,methylene thiol and isothiouronium moieties attached to polystyrene-divinylbenzene

Summary Commercially available polystyrene-divinylbenzene (PS-DVB) resins functionalized with isothiouronium (Tulsion CH-95), phosphinic acid (Tulsion CH-96) and methylene thiol (Tulsion CH-97) moieties have been used for separating palladium from nitric acid medium. Extraction of palladium has been studied as a function of time, concentration of nitric acid and palladium. The distribution coefficients (K_d, ml/g) of palladium on sulfur based resins (Tulsion CH-95 and Tulsion CH-97) are higher (5000-10⁴ml/g in 0.1M nitric acid) than on Tulsion CH-96 resin and decrease with increasing concentration of nitric acid. The initial rate of extraction of palladium by Tulsion CH-95 and Tulsion CH-97 resins was very rapid and the time required for the establishment of equilibrium was a function of palladium concentration in the aqueous phase. The rate data could be fitted by a second order rate equation and the magnitude of rate constant for the extraction of palladium by these resins (~10²M^-1. min^-1) decreased in the order of: Tulsion CH-95 > Tulsion CH-97 > Tulsion CH-96. The extraction isotherms of Tulsion CH-95 were fitted by Langmuir adsorption model and the coefficients were obtained by regression. The extraction capacity of palladium on Tulsion CH-95 was found to be ~20 mg/g at 3M nitric acid. Column experiments have been conducted and the data were fitted using Thomas model. A column utilization of 75% was achieved for the extraction of palladium by Tulsion CH-95 resin.