A rapid, reliable and accurate method for the determination of hexavalent chromium in Portland cement is developed. The proposed method includes direct spectrophotometric determination of Cr (VI) in Portland cement wi...A rapid, reliable and accurate method for the determination of hexavalent chromium in Portland cement is developed. The proposed method includes direct spectrophotometric determination of Cr (VI) in Portland cement with 1, 2, 5, 8 Tetrahydroxyanthraquinone, (Quinalizarin, QINZ) at pH 1.5. The European Directive (2003/53/EC) limits the use of cements so that it contains no more than 2 mg.Kg-1 of water-soluble Cr (VI). The absorbance at 565 nm due to Cr (VI)-QINZ complex is recommended for the determination of water-soluble Cr (VI) in Portland cement. The quantification of Cr (VI) released from cement when mixed with water is performed according to TRGS 613 (Technical Rules of Hazardous Substances). The validity of the method is thoroughly examined and the proposed method gives satisfactory results. A derivative spectrophotometric method has been developed for the determination of total Cr (VI) in Portland cement in the presence of Fe (III) and Ti (IV). The hexavalent chromium complex formed at pH 1.5 allows precise and accurate determination of chromium (VI) over the concentration range 0.05 to 3.0 mg.L-1of chromium (VI). The validity of the method was examined by analyzing several Standard Reference Material (SRM) Portland cement samples. The MDL (at 95% confidence level) was found to be 25 ng/mL for chromium (VI) in National Institute of Standards and Technology (NIST) cement samples using the proposed method.展开更多
A novel poly(vinyl chloride)membrane potentiometric sensor for chromium(Ⅲ)ions based on the use of 5,5′-(1,4-phenylene)bis(3-(naphthalen-1-yl)-4,5-dihydro-1H-pyrazole-1-carbothioamide)as a neutral ionophore was deve...A novel poly(vinyl chloride)membrane potentiometric sensor for chromium(Ⅲ)ions based on the use of 5,5′-(1,4-phenylene)bis(3-(naphthalen-1-yl)-4,5-dihydro-1H-pyrazole-1-carbothioamide)as a neutral ionophore was developed.The optimum composition of the best performing membrane contained ionophore,potassium tetrakis(p-chlorophenyl)borate(KTpClPB),dibutyl phthalate(DBP),and poly(vinyl chloride)(PVC)in the ratio of 5.5:1.5:55:38(mg).The sensor exhibits a working concentration range of 1.0×10^(-5)-1.0×10^(-1 )mol L^(−1) and a detection limit of 1.7×10^(-6) mol L^(−1).The sensor shows good selectivity for chromium(III)ions over a number of cations including alkali,alkaline earth,heavy and transition metals.The response time of the sensor is 8 s.In addition,the developed sensor shows good reusability and stability.The sensor operates in the wide pH range of 5.0-11.0.The sensor could be used as an indicator electrode in the quantification of Cr^(3+)ions by potentiometric titration against ethylenediaminetetraacetic acid(EDTA).Finally,this sensor was successfully used for the determination of chromium(III)in commercial water,purification water and wastewater.展开更多
国际标准 ISO 7530-1:2015 中测定铬含量,使用一氧化二氮-乙炔火焰原子吸收光谱法,现已极少应用。本文报告了“电感耦合等离子体原子发射光谱法测定镍合金中的铬含量的分析方法研究”试验工作,通过样品溶解试验、称样量试验、基体干扰...国际标准 ISO 7530-1:2015 中测定铬含量,使用一氧化二氮-乙炔火焰原子吸收光谱法,现已极少应用。本文报告了“电感耦合等离子体原子发射光谱法测定镍合金中的铬含量的分析方法研究”试验工作,通过样品溶解试验、称样量试验、基体干扰试验、内标元素选择试验等优化和确立了分析方法条件,建立了电感耦合等离子体原子发射光谱发测定镍合金中铬含量的分析方法。精密度试验、标样测试、方法比对、加标回收等试验表明所建立的方法是准确可靠的,满足了镍合金中铬含量的测定要求,可推荐作为国家标准。展开更多
文摘A rapid, reliable and accurate method for the determination of hexavalent chromium in Portland cement is developed. The proposed method includes direct spectrophotometric determination of Cr (VI) in Portland cement with 1, 2, 5, 8 Tetrahydroxyanthraquinone, (Quinalizarin, QINZ) at pH 1.5. The European Directive (2003/53/EC) limits the use of cements so that it contains no more than 2 mg.Kg-1 of water-soluble Cr (VI). The absorbance at 565 nm due to Cr (VI)-QINZ complex is recommended for the determination of water-soluble Cr (VI) in Portland cement. The quantification of Cr (VI) released from cement when mixed with water is performed according to TRGS 613 (Technical Rules of Hazardous Substances). The validity of the method is thoroughly examined and the proposed method gives satisfactory results. A derivative spectrophotometric method has been developed for the determination of total Cr (VI) in Portland cement in the presence of Fe (III) and Ti (IV). The hexavalent chromium complex formed at pH 1.5 allows precise and accurate determination of chromium (VI) over the concentration range 0.05 to 3.0 mg.L-1of chromium (VI). The validity of the method was examined by analyzing several Standard Reference Material (SRM) Portland cement samples. The MDL (at 95% confidence level) was found to be 25 ng/mL for chromium (VI) in National Institute of Standards and Technology (NIST) cement samples using the proposed method.
文摘A novel poly(vinyl chloride)membrane potentiometric sensor for chromium(Ⅲ)ions based on the use of 5,5′-(1,4-phenylene)bis(3-(naphthalen-1-yl)-4,5-dihydro-1H-pyrazole-1-carbothioamide)as a neutral ionophore was developed.The optimum composition of the best performing membrane contained ionophore,potassium tetrakis(p-chlorophenyl)borate(KTpClPB),dibutyl phthalate(DBP),and poly(vinyl chloride)(PVC)in the ratio of 5.5:1.5:55:38(mg).The sensor exhibits a working concentration range of 1.0×10^(-5)-1.0×10^(-1 )mol L^(−1) and a detection limit of 1.7×10^(-6) mol L^(−1).The sensor shows good selectivity for chromium(III)ions over a number of cations including alkali,alkaline earth,heavy and transition metals.The response time of the sensor is 8 s.In addition,the developed sensor shows good reusability and stability.The sensor operates in the wide pH range of 5.0-11.0.The sensor could be used as an indicator electrode in the quantification of Cr^(3+)ions by potentiometric titration against ethylenediaminetetraacetic acid(EDTA).Finally,this sensor was successfully used for the determination of chromium(III)in commercial water,purification water and wastewater.
文摘国际标准 ISO 7530-1:2015 中测定铬含量,使用一氧化二氮-乙炔火焰原子吸收光谱法,现已极少应用。本文报告了“电感耦合等离子体原子发射光谱法测定镍合金中的铬含量的分析方法研究”试验工作,通过样品溶解试验、称样量试验、基体干扰试验、内标元素选择试验等优化和确立了分析方法条件,建立了电感耦合等离子体原子发射光谱发测定镍合金中铬含量的分析方法。精密度试验、标样测试、方法比对、加标回收等试验表明所建立的方法是准确可靠的,满足了镍合金中铬含量的测定要求,可推荐作为国家标准。
