Chromium Speciation in Water by Sorption on Calcite and Determination by Electrothermal Atomic Absorption Spectrometry

Abstract

A rapid, sensitive, and accurate method for the separation and speciative determination of chromium (Cr)(VI) and Cr(III) in water samples has been developed using sorption as the separation technique in conjunction with final determination by electrothermal atomic absorption spectroscopy (ETAAS). The present method, where granular calcite is used as selective sorbent, separates Cr(III) with retention values up to 99%, resulting in high accuracy determination of Cr(VI). Total Cr was likewise determined by ETAAS after an efficient reduction of Cr(VI) to Cr(III) using ascorbic acid as reducing agent, deriving Cr(III) concentration from the difference between total Cr and Cr(VI). The parameters of the separation technique, solution pH (4.5–5.5), solution flow rate through the calcite column (0.14–0.42 mL min^?1), and calcite column internal diameter (1.5–3.0 cm), were evaluated. Best results were achieved with pH of 5.5, flow rate of 0.42 mL min^?1, and column internal diameter of 1.5 cm. Optimum determination conditions were found using magnesium nitrate [Mg(NO₃)₂] as chemical modifier, pyrolysis, and atomization temperatures of 1400 and 2200°C, respectively. In such conditions, the detection limits (n=10) were 1.5 and 0.8 µg L^?1 for Cr(III) and Cr(VI), respectively.     

微波消解-原子吸收法检测鸡组织中的重金属含量

采用微波消解原子吸收法测定鸡组织样品中的铅、镉、铜、铬等元素的含量 ,结果表明 :①组织中Pb的含量心脏 >肝脏 >肌胃 >胸肌 >肾脏 >腿肌 >骨骼 ,超标率分别为1 0 0 .0 % ,96.87% ,96.87% ,87.50 % ,1 0 0 .0 % ,81 .2 5% ,0 %。②组织中Cd的含量肾脏 >骨骼>腿肌 >肝脏 >心脏 >肌胃 >胸肌 ,超标率分别为 6.2 5% ,0 ,3 .1 3 % ,0 % ,0 % ,0 % ,0 %。③组织中Cu的含量心脏 >肝脏 >肾脏 >骨骼 >肌胃 >胸肌 >腿肌 ,超标率分别为 1 2 .50 % ,1 5.63 % ,9.3 8% ,3 .1 3 % ,0 % ,0 % ,0 %。④组织中Cr的含量肾脏 >肝脏 >心脏 >胸肌 >腿肌>骨骼 >肌胃 ,超标率分别为 50 .0 0 % ,62 .70 % ,9.3 8% ,3 .1 3 % ,0 % ,0 % ,0 %。     

Comparison of Lead Extraction and Detection Procedures for Six Canadian Soils

The effects of acid digestion procedures and instrumentation on extracted lead (Pb) concentrations from several soils, including a mildly Pb-contaminated soil, were determined using a two-factor factorial experiment. The two factors were (i) digestion procedure [seven levels: U.S. EPA, AOAC (dry ashing), nitric acid (NA), three aqua regia procedures (AR1, AR2, and AR3), and hydrofluoric acid (HF)] and (ii) instrumentation [two levels: atomic absorption spectrometry (AAS) and inductively coupled plasma (ICP) spectroscopy]. The greatest Pb recovery was obtained when soils were digested with HF and analyzed by AAS. The results suggest that the AOAC procedure (a standard procedure for recovery of soil nutrients and trace elements in Canadian laboratories) and EPA procedure (a standard procedure in American laboratories) may underestimate Pb concentrations in some Atlantic Canadian soil types. The AAS procedure is more accurate than ICP for determining Pb concentrations in soil with a history of PbHAsO₄, at least for Atlantic Canadian soils.     

Effects of Extraction Conditions on the Content of Anthocyanins and Bioelements in Berry Fruit Extracts

Abstract

Two methods for extracting anthocyanins and bioelements [calcium (Ca), magnesium (Mg), zinc (Zn), iron (Fe)] from black chokeberry, black currant, strawberry, and bilberry fruits were compared in this study. Correlations between the content of anthocyanins and bioelements in fruit extracts were determined using method A [extraction with hydrochloric acid (HCl)] and method B [extraction with water (H₂O)]. Relationships between the content of anthocyanins and particular nutrients, as well as between Mg and Ca and between Zn and Fe, in fruit extracts obtained by method A and by method B were also established.

The mean content of anthocyanins and bioelements (Ca, Mg, Zn, Fe) was the highest in black chokeberry fruits, regardless of the extraction method used. Bilberry fruits had the lowest nutrient content, despite a high anthocyanin content. The mean content of anthocyanins and bioelements was higher in fruit extracts obtained by method A than method B. The coefficients used to recalculate method A into method B were anthocyanins, 5.1; Ca, 1.1; Mg, 1.2; and Zn, 2.2. The statistical analysis showed that the effect of a given extraction method on the content of anthocyanins and bioelements (except for Ca) in fruit extracts depended on fruit species. The correlations between the content of anthocyanins, Ca, Mg and Zn in fruit extracts obtained by method A were found to be positive and highly significant, in comparison with method B. There was no correlation between the content of anthocyanins and particular nutrients in fruit extracts obtained by method A and by method B. The Mg content of fruit extracts was highly significantly higher than the Ca content, irrespective of the extraction method applied.     

不同消解方法对测定蒲公英中微量元素含量的影响

[目的]考察不同消解方法对蒲公英中Fe、Zn、Cu、Mn元素含量测定的影响。[方法]分别通过干法、湿法、微波法处理样品,利用原子吸收分光光度计测定样品中的4种元素含量。[结果]用微波法消解样品时,测得Cu、Zn、Fe、Mn含量分别为35.01、103.11、210.86、21.13μg/g,高于干法和湿法这2种消解方法处理。[结论]微波消解法适合用于植物样品微量元素测定的前处理。     

兰州市大气降雪中重金属污染的研究及来源分析

于2015年典型降雪月份1~2月采集了兰州市市区和郊区5场降雪样品,用火焰原子吸收分光光度法(福立AA1700)测定了雪水中溶解态的10种重金属元素(Cu、Hg、Cd、Mn、Al、Pb、Zn、Fe、Ni、Cr),研究了兰州市市区和郊区大气降雪样品的重金属含量特征,并分析了重金属的来源及变化规律。结果表明,兰州市市区大气降雪中重金属含量均明显高于郊区,且Pb元素含量最大,Mn元素市区比郊区高出最多,达86.22%。     

植物中微量镉检测方法的对比研究进展

镉是毒性最强和农田受污染最普遍的重金属之一,进入土壤的镉极易被植物吸收累积。为了提高植物中镉含量检测的准确性,文章综述了目前各种检测方法的发展和应用情况,主要对比分析了原子吸收光谱法、高效液相色谱法、电化学法和电感耦合等离子质谱法等方法的优缺点和应用范围,提出了对镉元素高效、快速、精确的分析检测技术是未来的研究方向。     

不同分析方法对水中金属污染指数测定效果的影响

为研究不同仪器分析方法对水中金属污染指数的检测结果是否存在影响,分别采用原子吸收分光光度法(AAS)和电感耦合等离子发射光谱法(ICP-OES)测定河南省新乡市1月、5月、9月3个不同月份的地表水和地下水,检测6个样本中6种金属元素的浓度,分析污染指数的差异性,同一水样中同一金属污染指数不同时间的变化趋势,评价其水质污染等级和现状.结果表明:所获得的36对重金属污染指数检测结果均有明显差异;获得的12对曲线图有9对具有明显差异,其水质污染等级评价结果也有一定差异.2种不同水样监测方法对污染指数测定存在偏差,使水质现状评价存在差异,不能真实反映元素浓度,污染指数水质评价失去了准确性、时效性,可能影响动物及人类对水的正确利用.     

城市行道树大叶黄杨和月季铅镉污染现状及评价

在天津交通干道外环、中环和内环每条采样路线上设置5个采样点,选取两种常见的植物大叶黄杨和月季的叶片作为研究对象,利用原子吸收光谱技术测定叶片中铅(Pb)、镉(Cd)的含量。结果表明,主要交通枢纽、大型车辆停靠区的外环叶片中铅镉的含量较高,高于小型车辆密集的中环与内环,而公园、学校区的叶片中重金属含量均较低;叶片铅镉含量均为秋季大于春季。通过测定叶片中重金属含量可为大气环境污染提供生物净化、生物监测手段。     

原子吸收分光光度法测定植物中微量元素的研究

采用原子分光光度法测定牛蒡、银杏、银杏叶和大蒜中Se、Cd、Pb含量,以期为该法用于植物微量元素测定提供参考。