Indirect Determination of Cyanide by Atomic Absorption Spectrometry

Abstract

Two methods for determination of cyanide by atomic absorption spectrometry (AAS) are developed. Both methods are based on the formation of an ion association compound between a metal complex, (Ag(CN)₂ ^? or Cu(CN)₃ ^2-), and a quaternary ammonium ion (benzyldimethylhexadecylammonium ion). The ion association compound is extracted into isomethylbutylketone (IBMK) and the metal is determined by AAS directly in extract. The method based on the formation of silver cyanide complex provides a reproducibility of 2.5%, a recovery of 99% and a detection limit of 1.7 μg/L while the method based on the formation of copper complex gives a reproducibility of 6%, a recovery of 93% and a detection limit of 0.6 μg/L. Several foreign ions were studied: the method based on the formation of Ag(CN)₂ ^? presents minor interferences.     

Cyanide Biodegradation by Trichoderma harzianum and Cyanide Hydratase Network Analysis

Cyanide is a poisonous and dangerous chemical that binds to metals in metalloenzymes, especially cytochrome C oxidase and, thus, interferes with their functionalities. Different pathways and enzymes are involved during cyanide biodegradation, and cyanide hydratase is one of the enzymes that is involved in such a process. In this study, cyanide resistance and cyanide degradation were studied using 24 fungal strains in order to find the strain with the best capacity for cyanide bioremediation. To confirm the capacity of the tested strains, cyano-bioremediation and the presence of the gene that is responsible for the cyanide detoxification was assessed. From the tested organisms, Trichoderma harzianum (T. harzianum) had a significant capability to resist and degrade cyanide at a 15 mM concentration, where it achieved an efficiency of 75% in 7 days. The gene network analysis of enzymes that are involved in cyanide degradation revealed the involvement of cyanide hydratase, dipeptidase, carbon–nitrogen hydrolase-like protein, and ATP adenylyltransferase. This study revealed that T. harzianum was more efficient in degrading cyanide than the other tested fungal organisms, and molecular analysis confirmed the experimental observations.     

痕量汞、氰化物及硫化物的冷原子荧光测定

本文介绍用冷原子荧光法测定汞、间接测定氰化物及硫化物的条件,干扰情况及干扰的消除。样品取自太湖底泥,结果表明,汞的标准偏差为0.0033,变异系数为9.4%,平均回收率为102%,可检出0.2ppb的汞量;氰化物的标准偏差为0.40,变异系数为8.3%,平均回收率为87%,可检出0.25ppb的CN~-;硫化物的标准偏差为3.0,变异系数为6.5%,可检出2ppb的S~-。     

Cyanide Hydratase Modification Using Computational Design and Docking Analysis for Improved Binding Affinity in Cyanide Detoxification

Cyanide is a hazardous and detrimental chemical that causes the inactivation of the respiration system through the inactivation of cytochrome c oxidase. Because of the limitation in the number of cyanide-degrading enzymes, there is a great demand to design and introduce new enzymes with better functionality. This study developed an integrated method of protein-homology-modelling and ligand-docking protein-design approaches that reconstructs a better active site from cyanide hydratase (CHT) structure. Designing a mutant CHT (mCHT) can improve the CHT performance. A computational design procedure that focuses on mutation for constructing a new model of cyanide hydratase with better activity was used. In fact, this study predicted the three-dimensional (3D) structure of CHT for subsequent analysis. Inducing mutation on CHT of Trichoderma harzianum was performed and molecular docking was used to compare protein interaction with cyanide as a ligand in both CHT and mCHT. By combining multiple designed mutations, a significant improvement in docking for CHT was obtained. The results demonstrate computational capabilities for enhancing and accelerating enzyme activity. The result of sequence alignment and homology modeling show that catalytic triad (Cys-Glu-Lys) was conserved in CHT of Trichoderma harzianum. By inducing mutation in CHT structure, MolDock score enhanced from −18.1752 to −23.8575, thus the nucleophilic attack can occur rapidly by adding Cys in the catalytic cavity and the total charge of protein in pH 6.5 is increased from −6.0004 to −5.0004. Also, molecular dynamic simulation shows a stable protein-ligand complex model. These changes would help in the cyanide degradation process by mCHT.     

An Indirect Determination of Some Ions by Flameless Atomic Absorption Using a Wire Loop Atomizer

Abstract

In previous studies using a wire loop atomizer with a preconcentrating soaking step it has been reported that there are sometimes interferences due to other species in the sample besides the metal of interest. It is possible to use this interference to advantage as an indirect method for some anions and metals that are determined only with poor sensitivity by atomic absorption spectroscopy. Cyanide, lanthanum, and zirconium were studied to determine if useful calibration curves and low detection limits could be obtained by this indirect method.     

数码比色法测定环境及生物样品中的氰化物浓度

在传统氰化物检测方法的基础上,提出了一种新的方法—数码比色法。在一定条件下,苦味酸与氰化物生成黄色化合物,用数码相机对显色溶液拍照,通过数码比色,进行灰度处理,照片的三原色值与氰化物的浓度成线性关系,可以直接分析出其氰化物的浓度。对唾液样品测定,其回收率为98.18%,对照品测定的相对标准偏差RSD为1.5%。研究结果表明,数码比色法具有准确度和精密度都比较理想,方便快速、环境友好等特点。     

流动注射分析法测定废水中的氰化物

建立流动注射分析法测定工业废水中氰化物浓度的方法。水样及试剂在蠕动泵的作用下进入管道,先后经过蒸馏模块与化学模块,最后进入检测模块得出系统处理后的数据。通过对实际样品和标准样品的分析得出该方法的检出限为1.55μg/L,相对误差小于5%。氰化物质量浓度在0~500μg/L范围内与信号值呈良好的线性关系,线性相关系数r2=0.999 9。测定结果的相对标准差为0.1%~3%(n=4),加标回收率为93.3%~102.0%。该方法实现了自动进样、在线蒸馏,具有分析速率快、试剂耗量少等优点,可用于水和废水中总氰化物的测定。     

Microdetermination of Cyanide

Abstract

A volumetric procedure is described for the micro-determination of cyanide. Small amounts of cyanide can be estimated even in presence of chloride if it is present in the electrolytic bath. N-Bromosuccinimide (NBS) is used to quantitatively oxidized cyanide to cyanate. The end point is reached when the rose red color of the bordeaux red is changed to distinct yellow. From 1–6 mg. of cyanide were analyzed with an average relative standard deviation of about 0.66%.     

A Fluorometric Method for Cyanogen (C2N2) with No Cyanide Interference

Abstract

A fluorometric method for the analysis of cyanogen (C₂N₂, ethanedinitrile) without cyanide interference is described the procedure is based on the reaction of C₂N₂ with hexamethylenetetramine (HMTA) to produce a fluorophor. the fluorescence yield is linear over a range of 3–4 orders of magnitude. the method is comparable in detection limits to CN^? measurements done electrochemically; in this case >10^?2?<10^?5 M. Many anions and cations were examined for interference; only transition and heavy metal compounds reduced fluorescence. Certain amines may interfere, although all examined reacted much slower than the HMTA.     

火焰原子吸收光谱法测定焙烧氰化尾渣中的银

建立了火焰原子吸收光谱法测定焙烧氰化尾渣中银的分析方法。试样经盐酸、硝酸、氢氟酸、高氯酸溶解,在盐酸介质中实现银含量的准确测定。利用氢氟酸破坏硅酸盐结构可溶解样品中硅酸盐类的特点,通过多种酸配合溶解,解决了氰化尾渣焙烧后出现硅酸盐包裹银元素,进而导致测定结果严重偏低的问题。研究表明,样品经拟定的方法处理,方法检出限为0.003 0mg/L;加标回收率98.90%~101.1%。此方法能满足焙烧氰化尾渣中银含量测定。     

An Efficient Probe for Rapid Detection of Cyanide in Water at Parts per Billion Levels and Naked‐Eye Detection of Endogenous Cyanide

A new molecular probe based on an oxidized bis‐indolyl skeleton has been developed for rapid and sensitive visual detection of cyanide ions in water and also for the detection of endogenously bound cyanide. The probe allows the “naked‐eye” detection of cyanide ions in water with a visual color change from red to yellow (Δλ_max=80 nm) with the immediate addition of the probe. It shows high selectivity towards the cyanide ion without any interference from other anions. The detection of cyanide by the probe is ratiometric, thus making the detection quantitative. A Michael‐type addition reaction of the probe with the cyanide ion takes place during this chemodosimetric process. In water, the detection limit was found to be at the parts per million level, which improved drastically when a neutral micellar medium was employed, and it showed a parts‐per‐billion‐level detection, which is even 25‐fold lower than the permitted limits of cyanide in water. The probe could also efficiently detect the endogenously bound cyanide in cassava (a staple food) with a clear visual color change without requiring any sample pretreatment and/or any special reaction conditions such as pH or temperature. Thus the probe could serve as a practical naked‐eye probe for “in‐field” experiments without requiring any sophisticated instruments.     

Continuous Determination of Free Cyanide by Means of Membrane Diffusion of Gaseous HCN and An Electrode Indicator Technique

Abstract

A continuous measurement system for free cyanide has been developed based on the principle of diffusion across a gas-permeable membrane to affect the separation of hydrogen cyanide from the acidified sample solution. The cyanide absorbed in the alkaline indicator solution is subsequently analyzed by an indirect technique using a silver ion-selective electrode. In the concentration range of 30 to 400 μg CN^?/L, the accuracy and precision of this method is approximately two percent. The detection limit of this system is approximately 0.5 μg CN^?/L.     

金属配位剂衍生-高效液相色谱法测定粮食及白酒中的游离氰化物

采用金属配位剂Ni(Ⅱ)-NH3作为衍生剂,与游离氰化物反应生成稳定且具有高紫外吸收值的Ni(CN)_4~(2-),使用高效液相色谱-紫外检测法(HPLC-UV)检测游离氰化物.方法的线性范围为0.014～0.540 mg/L,相关系数R~2=0.9984,检出限为4.0 μg/L.该方法简便快速,抗干扰能力强,灵敏度高,适于食品、环境、生物等样品中游离氰化物的检测.     

原子吸收分光光度计石墨炉原子化法故障排除及原因分析

以PinAAcle 900T型原子吸收分光光度计（AAS）为研究对象,针对其石墨炉原子化法中常见的故障进行判断,并提出相应的解决措施.     

间接原子吸收法测定药物制剂中利血生的含量

提出了利血生的间接原子吸收法，该法基于利血生在碱性介质中的分离－产物半胱氨酸在适当的PH条件下与铜离子生成灰色沉淀，通过测定上清液中铜的含量来间接测定利血生的含量，在法在10－100mg/L范围内呈良好的线性关系（r=0.9992),回收率为98．5％－101．6％。该法可成功地用于药物制剂中利血生的测定。     

盐酸苯海拉明的原子吸收法测定

探讨了盐酸苯海拉明在适当的酸性条件下与锌试剂、铜离子定量生成三元络合物,经ＭＩＢＫ萃取,以ＡＡＳ法测定萃取液听 铜来间接测定盐酸苯海拉明的量。本法与药典法相比,相对平均偏差小于０．４％,线性范围为５～５０μｇ．ｍＬ＾－１。回收率为９７％～１０２％。     

A Sensitive Colorimetric Reagent for the Determination of Cyanide and Hydrogen Cyanide in Various Environmental Samples

A sensitive reagent system is proposed for the determination of cyanide and hydrogen cyanide in various environmental samples. The method is based on the conversion of cyanide into cyanogen bromide followed by its reaction with pyridine to form glutaconic aldehyde. The glutaconic aldehyde so formed is coupled with p‐aminoacetophenone forming yellow‐orange polymethine dye measured at 445 nm. The colour system obeys Beer's law in the range of 0.01–0.16 ppm of cyanide inaqeous phase and 0.002–0.03 ppm in extracting system. The molar absorptivity and Sandell's sensitivity were found to be 6.51 × 10⁵ l mol^?1 cm^?1 and 0.0001 μg cm^?2, respectively. The method has been successfully applied for the determination of cyanide in air, industrial effluent, biological samples, and in the pesticide acrylonitrile.     

Cyanide by Prussian Blue Spot Formation

Abstract

A simple quantitative test for cyanide is described. Cyanide is released as the hydrocyanic acid and conducted through a prepared disk to form a prussian blue spot. This spot is visually or instrumentally compared to standard spots. Two μg of cyanide can be detected by this method.     

石墨炉原子吸收分析中锰的原子化过程探讨

本文采用计算机联机技术,测定并计算了锰原子吸收的时间分辨信号,得出在信号的初始几百毫秒为一级反应动力学过程,在升温速率较小的近恒温条件下为零级反应动力学过程。借助探针技术对石墨表面进行X射线光电子能谱(XPS)分析,表明锰在石墨炉中的原子化经过锰的高价氧化态到低价氧化态,最后氧化锰气相分解生成锰原子。