Flame atomic absorption spectrometric determination of trace quantities of cadmium in water samples after cloud point extraction in Triton X-114 without added chelating agents

A new micell-mediated phase separation method for preconcentration of ultra-trace quantities of cadmium as a prior step to its determination by flame atomic absorption spectrometry has been developed. The method is based on the cloud point extraction (CPE) of cadmium in iodide media with Triton X-114 in the absence of any chelating agent. The optimal extraction and reaction conditions (e.g., acid concentration, iodide concentration, effect of time) were studied, and the analytical characteristics of the method (e.g., limit of detection, linear range, preconcentration, and improvement factors) were obtained. Linearity was obeyed in the range of 3-300 ng mL(-1) of cadmium. The detection limit of the method is 1.0 ng mL(-1) of cadmium. The interference effect of some anions and cations was also tested. The method was applied to the determination of cadmium in tap water, waste water, and sea water samples.     

An on-line pre-concentration system for determination of cadmium in drinking water using FAAS

In the present paper, a minicolumn of polyurethane foam loaded with 4-(2-pyridylazo)-resorcinol (PAR) is proposed as pre-concentration system for cadmium determination in drinking water samples by flame atomic absorption spectrometry. The optimization step was performed using two-level full factorial design and Doehlert matrix, involving the variables: sampling flow rate, elution concentration, buffer concentration and pH. Using the established experimental conditions in the optimization step of: pH 8.2, sampling flow rate 8.5 mL min(-1), buffer concentration 0.05 mol L(-1) and elution concentration of 1.0 mol L(-1), this system allows the determination of cadmium with detection limit (LD) (3sigma/S) of 20.0 ng L(-1) and quantification limit (LQ) (10sigma/S) of 64 ng L(-1), precision expressed as relative standard deviation (R.S.D.) of 5.0 and 4.7% for cadmium concentration of 5.0 and 40.0 microg L(-1), respectively, and a pre-concentration factor of 158 for a sample volume of 20.0 mL. The accuracy was confirmed by cadmium determination in the standard reference material, NIST SRM 1643d trace elements in natural water. This procedure was applied for cadmium determination in drinking water samples collected from Salvador City, Bahia, Brazil. For five samples analyzed, the achieved concentrations varied from 0.31 to 0.86 microg L(-1).     

Simultaneous flow injection preconcentration of lead and cadmium using cloud point extraction and determination by atomic absorption spectrometry

A flow injection (FI) micelle-mediated separation/preconcentration procedure for the determination of lead and cadmium by flame atomic absorption spectrometry (FAAS) has been proposed. The analytes reacted with 1-(2-thiazolylazo)-2-naphthol (TAN) to form hydrophobic chelates, which were extracted into the micelles of 0.05% (w/v) Triton X-114 in a solution buffered at pH 8.4. In the preconcentration stage, the micellar solution was continuously injected into a flow system with four mini-columns packed with cotton, glass wool, or TNT compresses for phase separation. The analytes-containing micelles were eluted from the mini-columns by a stream of 3molL(-1) HCl solution and the analytes were determined by FAAS. Chemical and flow variables affecting the preconcentration of the analytes were studied. For 15mL of preconcentrated solution, the enhancement factors varied between 15.1 and 20.3, the limits of detection were approximately 4.5 and 0.75microgL(-1) for lead and cadmium, respectively. For a solution containing 100 and 10microgL(-1) of lead and cadmium, respectively, the R.S.D. values varied from 1.6 to 3.2% (n=7). The accuracy of the preconcentration system was evaluated by recovery measurements on spiked water samples. The method was susceptible to matrix effects, but these interferences were minimized by adding barium ions as masking agent in the sample solutions, and recoveries from spiked sample varied in the range of 95.1-107.3%.     

锌镉还原法测定水中硝酸盐浓度

本文通过采用添加人工海水调节盐度的办法,采用锌镉还原法测定盐度不确定的环境样品,特别是河口水样中硝酸盐浓度,解决了多数常用的硝酸盐分析方法容易受到氯化物干扰的问题,方法标准曲线回归系数达到0·9997,实际样品分析的加标回收率在98·8%~103%之间。但是,该方法影响因素比较多,测定时需要严格控制。     

Determination of trace nickel in water samples by cloud point extraction preconcentration coupled with graphite furnace atomic absorption spectrometry

A new method based on the cloud point extraction (CPE) preconcentration and graphite furnace atomic absorption spectrometry (GFAAS) detection was proposed for the determination of trace nickel in water samples. When the micelle solution temperature is higher than the cloud point of surfactant p-octylpolyethyleneglycolphenyether (Triton X-100), the complex of Ni2+ with 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone (PMBP) could enter surfactant-rich phase and be concentrated, then determined by GFAAS. The main factors affecting the cloud point extraction were investigated in detail. An enrichment factor of 27 was obtained for the preconcentration of Ni2+ with 10 mL solution. Under the optimal conditions, the detection limit of Ni2+ is 0.12 ng mL(-1) with R.S.D. of 4.3% (n = 10, c = 100 ng mL(-1)). The proposed method was applied to determination of trace nickel in water samples with satisfactory results.     

Determination of trace bismuth in human serum by cloud point extraction coupled flow injection inductively coupled plasma optical emission spectrometry

A cloud point extraction method for the preconcentration of ultra-trace bismuth in human serum prior to its determination by inductively coupled plasma optical emission spectrometry had been developed in this paper. The cloud point extraction method was based on the complex of Bi(III) with 8-hydroxyquinoline and Triton X-114 was used as non-ionic surfactant. The main factors affecting cloud point extraction efficiency, such as pH of solution, concentration of complexing agent, concentration of non-ionic surfactant, equilibration temperature and time were investigated in detail. An enrichment factor of 81 was obtained for the preconcentration of Bi(III) with 25 mL solution. Under the optimal conditions, the detection limit of Bi(III) is 0.12 μg L⁻¹. The relative standard deviation (n = 7) of determination was 2.3%, values of recovery of bismuth were from 92.3% to 94.7% for three samples. This method is simple, accurate, sensitive and can be applied to the determination trace bismuth in human serum.     

离子色谱法测定饮用水中常见阴离子

本文主要介绍离子色谱法检测饮用水中常见阴离子的方法。本方法采用瑞士万通的761型离子色谱仪。分离柱为METROSEPAnionDual2,淋洗液为2.0mmol/LNaHCO3和1.3mmol/LNa2CO3抑制液为20mmol/LH2SO4在测定范围内,F-、Cl-、NO2-、NO32-;-SO42-的峰面积和质量浓度呈线性关系,相关系数均大于0.999。回收率F-为101.5%,CL-O101.6%,NO2-为108.0%.NO32-为97.7%,SO42-为103.3%。相对标准偏差在0.7%-4.3%之间。     

牛血清白蛋白荧光猝灭法测定药物中的头孢硫脒

应用牛血清白蛋白(BSA)荧光猝灭法建立一种测定药物中头孢硫脒(C-18)物质量浓度的新方法.BSA具有很强的内源荧光性,而C-18溶液本身不产生荧光.当C-18与BSA结合后,会导致其荧光强度下降.BSA在λex=340 nm处结合C-18后的荧光猝灭强度与C-18的量在一定范围内呈良好的线性关系,据此建立测定药品中C-18含量的新方法.该结合物的最大发射波长为λmax=340 nm,与C-18摩尔浓度在2.5×10-6～3×10-5mol/L范围内线性关系良好.其线性回归方程为△F=2.177 95× 107CC-18-28.007,相关系数r=0.9962,检出限为1.60×10-6mol/L,RSD为0.24％～0.30％,加标回收率为94.36％～97.52％.该方法操作简便、快速,可用于实际样本的测定,结果满足要求.     

反相高效液相色谱法测定饮用水中的酚类化合物

介绍了反相高效液相色谱法测定饮用水中的酚类物质。该法采用的固相萃取预处理法操作简便,节省溶剂,且稳定性好,回收率高。实验以ODS柱为分离柱,采用梯度洗脱,可编程紫外检测器进行样品检测。方法准确,重现性好,杂质干扰少,检出限低。     

气相色谱法测定饮用水源中四氯化碳

基于FYGC-2000(C)气相色谱仪气相色谱法测定了饮用水源中四氯化碳含量,所得的回归方程为=79477X-6097.8相关系数r=0.9998,2μg/L和10μg/L两个浓度电位的精密度试验中的所得标准偏差分别为3.3778％和0.742％.在加标回收率测试中加标量分别为2 ug/L和5 ug/L时,回收率在99...     

Determination of dopant concentration in co-deposited organic thin films by using RBS and X-ray fluorescence combined techniques

Organic light emitting diodes using phosphorescent dyes (PHOLEDs) have excellent performance and an internal quantum efficiency approaching 100%. To maximize performance, PHOLED devices use a conductive organic host material with a phosphorescent guest that is sufficiently dispersed to avoid concentration quenching. One of the most widely used organic compounds, green phosphorescent fac-tris(2-phenylpyridine)iridium, or [Ir(ppy)₃], can be used to produce PHOLEDs with very high external quantum efficiency by doping host material at different nominal concentrations. In this study, a methodology to accurately establish dopant concentration in co-deposited organic layers is proposed and discussed. X-ray fluorescence (XRF) and Rutherford backscattering (RBS) analyses were performed in co-deposited organic thin films and then combined to provide an accurate methodology. [Ir(ppy)₃] was used at different concentrations in two different hosts – 2,7-bis(9-carbazolyl)-9,9-spirobifluorene (Spiro2-CBP) and copper phthalocyanine (CuPc) – to test the proposed methodology. As Cu peak is easily detected by RBS, the CuPc host was chosen for calibration purposes, allowing more accurate determination of [Ir(ppy)₃] concentration. A linear correlation between the RBS and the XRF measurement data was found allowing the drawing up of a calibration chart used to determine the [Ir(ppy)₃] mass content in co-deposited films.     

原子荧光法烟叶土壤砷的测定

本文应用原子荧光法测定了福建省不同地区烟叶土壤中的砷,对仪器条件和试剂使用进行研究,得到检出限为0.079μg/L,相对标准偏差1.45%,加标回收率为92%-105%,结果表明该法操作简便,准确度高,精密度好。     

熔融制样X射线荧光光谱法测定矿石中五氧化二钒的含量

使用熔融制样-X射线荧光光谱法(XRF),以四硼酸锂做熔剂,样品与熔剂比为1∶10熔融制样.分析矿石中0.006％～98％的五氧化二钒含量.目前五氧化二钒标准物质较少,不能满足各含量段矿石类样品的准确定量要求.本方法通过加入高纯V2O5制备人工标准样品和现有五氧化二钒标准物质相结合绘制工作曲线,解决了现有标准物质较少的...     

Electrochemical determination of cadmium(II) at platinum electrode modified with kaolin by square wave voltammetry

In this work, determination of cadmium(II) using square wave voltammetry (SWV) was described. The method is based on accumulation of these metal ions on kaolin platinum electrode (K/Pt). The K/Pt performance was optimized with respect to the surface modification and operating conditions. The optimized conditions were obtained in pH of 5.0 and accumulation time of 25 min. Under the optimal conditions, the relationship between the peak current versus concentration was linear over the range of 9 × 10⁻⁸ to 8.3 × 10⁻⁶ mol L⁻¹. The detection limit (DL, 3σ) was 5.4 × 10⁻⁹ mol L⁻¹. The analytical methodology was successfully applied to monitor the Cd(II) content in natural water. Interferences were also evaluated.     

微波消解-氢化物发生原子荧光法测定土壤中硒

本研究采用了微波消解和传统电热板消解土壤样品,用原子荧光法测定土壤中的硒含量,结果表明,微波,消解的方法对总硒测定结果准确而稳定,而且节约时间和试剂。     

Separation and preconcentration of cadmium ions using octadecyl silica membrane disks modified by methyltrioctylammonium chloride

A simple and selective method for the determination of cadmium in water samples by FAAS after solid phase extraction has been developed. The method is based on the sorption of cadmium as CdI(4)(2-) on octadecyl silica membrane disks modified by cationic surfactant of methyltrioctylammonium chloride in the pH range of 1-8. The sorbed cadmium is then eluted with 10ml of 1moll(-1) nitric acid in ethanol and is measured by flame atomic absorption spectrometry. The influence of flow rates of eluent and sample solution, iodide concentration and amount of surfactant in retention and elution of cadmium from disks was also investigated. A preconcentration factor of 100 was achieved by passing 1000ml of sample through the membrane disk. The limit of detection (LOD) of cadmium was found to be 0.014ngml(-1). Precision at 2.5mugl(-1) was 1.2% (n=8). The method was successfully applied to the determination of cadmium in some natural water samples. The accuracy was assessed through recovery experiment, independent analysis by graphite furnace atomic absorption spectrometry, and analysis of certified reference waters.     

Stability of single-wall silicon carbide nanotubes – molecular dynamics simulations

One-dimensional silicon carbide (SiC) nanotubes and nanowires are both realizable and may co-exist. The stability of SiC nanotubes relative to nanowires and against heating is still unknown. Using classical molecular dynamics simulations, the authors investigate the stabilities of SiC nanotubes; as a first step, the study focuses on single-wall nanotubes (SWNTs). The results show that SiC nanotubes are more stable than nanowires below a critical diameter of about 1.6 nm, while SiC nanowires are more stable than nanotubes beyond that. As temperature increases, melting takes place at about 1620 K in SiC nanotubes by heterogeneous nucleation from the non-hexagonal defects due to reconstruction at a free end, and at about 1820 K in nanotubes without free ends by homogeneous nucleation within the wall from thermally activated 5-7-7-5 defects. In both cases formation of Si–Si and C–C bonds proceeds melting.     

Cloud point extraction for determination of lead in blood samples of children, using different ligands prior to analysis by flame atomic absorption spectrometry: a multivariate study

The phase-separation phenomenon of non-ionic surfactants occurring in aqueous solution was used for the extraction of lead (Pb²⁺) from digested blood samples after simultaneous complexation with ammonium pyrrolidinedithiocarbamate (APDC) and diethyldithiocarbamate (DDTC) separately. The complexed analyte was quantitatively extracted with octylphenoxypolyethoxyethanol (Triton X-114). The multivariate strategy was applied to estimate the optimum values of experimental factors. Acidic ethanol was added to the surfactant-rich phase prior to its analysis by flame atomic absorption spectrometer (FAAS). The detection limit value of Pb²⁺ for the preconcentration of 10 mL of acid digested blood sample was 1.14 μg L⁻¹. The accuracy of the proposed methods was assessed by analyzing certified reference material (whole blood). Under the optimized conditions of both CPE methods, 10 mL of Pb²⁺ standards (10 μg L⁻¹) complexed with APDC and DDTC, permitted the enhancement factors of 56 and 42, respectively. The proposed method was used for determination of Pb²⁺ in blood samples of children with kidney disorders and healthy controls.     

氢化物原子荧光光谱法同时测定生活饮用水中砷和硒

建立了氢化物发生原子荧光光谱法同时测定生活饮用水中砷和硒的方法.测试结果表明砷和硒在质量浓度分别为0.00μg/L~10.00μg/L和0.00μg/L~40.00μg/L范围内呈线性关系,相关系数分别为(砷r=0.9998,硒r=0.9997)。仪器检出限为砷:0.03μg/L硒:0.05μg/L。本方法检出限砷为0.075μg/L;硒为0.125μg/L。水质样品中砷的回收率为92.6%~96.5%,精密度为0.8%~1.4%;硒的回收率为91.2%~97.4%,精密度为1.0%~1.6%。应用本方法测定生活饮用水中的砷和硒方法简便、快速,结果准确可靠,较好地提高了工作效率。