Determination of trace metals in Nile River and ground water by differential pulse stripping voltammetry

The determination of trace metals in river water and ground water by DPSV is seriously disturbed by the presence of organic complexes. The influence of these substances can be eliminated by acidification of the samples with acids. Cd, Pb and Cu were determined at pH 1.1 (HNO₃ medium) and Zn, Cd, Pb and Cu at pH 2 (HCl medium), in both the Nile river and ground water. Zn was determined at pH 3.5 in HCl and pH 4.5 in HNO₃, after neutralizing the samples with NH₃/NH₄Cl buffer. Manganese could then be determined, after further addition of ammoniacal buffer solution up to pH 7.5 and 8.5. Ni and Co were determined in the adsorptive mode after formation of dimethylglyoximates at pH 9.2. The effect of pH on the stripping peaks of manganese was studied. Good agreement was observed between DPSV and AAS results for Zn, Cd, Pb, Cu and Mn, but the concentrations of Ni and Co were below the detection limits for AAS. Good agreement was obtained between DPSV results in HCl and HNO₃ for Ni and Co. The results indicate that decomposition of organic complexes by acidification with HNO₃ is better than in the case with HCl for Zn, Pb, Cu, Ni and Co, but HCl is better than HNO₃ for Cd and Mn.     

Determination of trace metals accumulated and internalized by marine phytoplankton; interferences with colloidal organic matter

In the present work, we study the effects that aggregation of humic acids in seawater, and its adsorption to surfaces, can have on the determination of Cu and Pb accumulation by phytoplankton within the context of metal bioavailability studies, using the diatom Thalassiosira weissflogii. Two methods commonly used for collection of algae to analyse metal content, filtration and centrifugation, were compared, and a procedure to differentiate the metal internalized by the alga from that adsorbed to cell walls-washing with 0.01?M ethylenediaminetetraacetic acid (EDTA)- was optimized for its use in seawater and in the presence of humic acids. The present results highlight the possibility of obtaining biased results if filtration is used to isolate the algae, and show that centrifugation is a more suitable procedure minimizing contribution of particulate and colloidal forms of metals to the measured cellular and intracellular metal contents. Thus a combination of centrifugation to isolate the algae from the medium with a 10 minutes washing with a washing agent composed of EDTA 0.01?M at pH 8 and NaCl and KCl to 0.5?M ionic strength is recommended to extract metals adsorbed to the surfaces of marine phytoplankton for a seawater containing humic substances. The importance of discriminating between internalized metal and total cellular metal in bioavailability studies is noted, given the different effects of humic substances on metal accumulation in the different cellular pools.     

Determination of trace amounts of gold in acid-attacked environmental samples by atomic absorption spectrometry with electrothermal atomization after preconcentration

A method for determination of trace amounts of gold in environmental samples (rocks, soils, sediments, and waters) by atomic absorption spectrometry with electrothermal atomization (ETAAS) after preconcentration using a chelating sorbent Spheron Thiol 1000 is described. The method accurately determines gold between 0.001 and several tens of grams per ton in samples having complex variations in mineralogy. Pulverized samples are roasted at 650°C to oxidize any sulfide and/or carbonaceous material. Samples are then subjected to a series of acid treatments to eliminate any silica matrix and to dissolve the sample. The Spheron Thiol 1000 is added to the sample solution, and then with sorbed gold is filtered out, washed, and ignited at 550°C. The residue is dissolved in aqua regia, evaporated, dissolved in distilled water, transferred to a volumetric flask, and analyzed by ETAAS.The limits of detection of gold, based on the 3 definition, were 0.5 ng g^–1 for 10-g samples (rocks, sediments, soils) and 0.05 ng mL^–1 for 1-L water samples. Precision of determination expressed by the relative standard deviation varied from 2.9% to 16.4%. The accuracy of the method is verified by analysis of certified reference materials. The obtained analytical results are in good agreement with attested values. The developed method was applied for gold determination in environmental samples affected by the acidification (acid mine drainage which is mainly a product of pyrite oxidation) from an open quartzite mine in the obov region situated NE of the city of Banská tiavnica (Slovakia).     

电感耦合等离子体原子发射光谱(ICP-AES)法测定锡铅焊料中11种微量元素

根据目前市场上常见锡铅焊料中主元素的特性(锡含量范围0.X%~95%,铅含量范围X%~99%),合理选择了有效的样品前处理方法。参考铸造锡铅焊料牌号及化学成分和仪器工作条件,确定了待测元素的测定范围。应用电感耦合等离子体原子发射光谱法同时测定锡铅焊料中锑、铋、铁、砷、铜、银、锌、铝、镉、磷、金11种元素的含量,方法操作简单。选择了合适的分析谱线,进行了基体元素对待测元素以及各待测元素之间的干扰研究,基体效应小,各待测元素之间基本无干扰,11次独立的测定数据相对标准偏差为1.0%~11.3%,方法的加标回收率为90.2%~105%。完全能满足现实生产中对锡铅焊料杂质元素的测定要求。     

Determination of trace amounts of nitrogen in uranium based samples by ion chromatography (IC) without Kjeldahl distillation

A simple, sensitive and fast ion chromatographic (IC) method with suppressed conductivity detection is described for the determination of traces of nitrogen in uranium based fuel materials. Initially a method was developed to determine nitrogen as NH₄⁺ using cation exchange column after matrix separation by Kjeldahl distillation. The method was then improved by eliminating this distillation. Matrix separation after sample dissolution was done by hydrolyzing and filtering off the polyvalent cations. This had helped in reducing both the sample size and analysis time. Optimization of dissolution conditions for various kinds of uranium based samples was done to keep acid content minimum; a prerequisite chromatographic condition. The calibration plot for nitrogen was linear in the concentration range of 0.02-1 mg L⁻¹ with regression coefficient of 0.9999. The relative standard deviation (R.S.D.) obtained in this method (100 μL injected) was 3% and 2% in 9 replicates at nitrogen level of 28 and 55 ng g⁻¹, respectively. Detection limit based on S/N = 3 (100 μL injected) as well as three times of variation in blank value was 4 ng g⁻¹. The developed method was authenticated by comparison with certified uranium-alloy standard as well as with independent indophenol photometry method. The developed method was applied to uranium-alloy, uranium-metal, sintered UO₂ pellets and sintered UO₂ microspheres samples.     

Determination of metals in marine species by microwave digestion and inductively coupled plasma mass spectrometry analysis

A microwave digestion method suitable for determination of multiple elements in marine species was developed, with the use of cold vapor atomic spectrometry for the detection of Hg, and inductively coupled plasma mass spectrometry for all of the other elements. An optimized reagent mixture composed of 2 ml of HNO₃, 2 ml of H₂O₂ and 0.3 ml of HF used in microwave digestion of about 0.15 g (dry weight) of sample was found to give the best overall recoveries of metals in two standard reference materials. In the oyster tissue standard reference material (SRM 1566b), recoveries of Na, Al, K, V, Co, Zn, Se, Sr, Ag, Cd, Ni, and Pb were between 90% and 110%; Mg, Mn, Fe, Cu, As, and Ba recoveries were between 85% and 90%; Hg recovery was 81%; and Ca recovery was 64%. In a dogfish certified reference material (DORM-2), the recoveries of Al, Cr, Mn, Se, and Hg were between 90% and 110%; Ni, Cu, Zn, and As recoveries were about 85%; and Fe recovery was 112%. Method detection limits of the elements were established. Metal concentrations in flounder, scup, and blue crab samples collected from coastal locations around Long Island and in the Hudson River estuary were determined.     

Determination of Osmium(VIII) and Palladium(II) in Mixtures by Derivative Spectrophotometry

Abstract

A sensitive method for the simultaneous determination of osmium(VIII) and Palladium(II) (up to 15 μ9/ml of Os and 11 μ9/ml of Pd) in mixtures, by first and second derivative spectrophotometry, using allyl thiourea as reagent, is described.

A statistical analysis of the results is reported.     

Determination of trace arsenic(III) by differential-pulse anodic stripping voltammetry with in-situ plated bismuth-film electrode

Abstract

A systematic survey of the quality status of the main aquifers in rural areas of Catalonia (Spain) regarding pesticide pollution has been carried out. A total number of 139 wells, distributed among 13 different hydrogeological units have been sampled and analyzed by GC-MS and GC-ECD, during the period 1997—98. Pesticides monitored were selected among triazine herbicides, organochlorine and organophosphorus insecticides. A positive presence of pesticides has been detected in 84.2% of the samples analyzed, 23.7% of them exceeding the requirements of the EU drinking water Directive (98/83/CE). Organochlorine insecticides were present in 62.6% of the samples, triazines in 49% and organophosphorus insecticides in 28.8%. The results obtained have been interpreted by Principal Component Analysis.     

Application of ruthenium catalyzed oxidation of [tris(2-aminoethyl)amine] in trace determination of ruthenium in environmental water samples

The ruthenium catalyzed oxidation of tris(2-aminoethyl)amine (TREN) by hexacyanoferrate(III) has been utilized for the development of a new and sensitive catalytic kinetic method (CKM) for the determination of ruthenium(III). The reaction was followed spectrophotometrically by the decrease in absorbance at 420nm (lambda(max) of [Fe(CN)(6)](3-)). The CKM developed utilizes fixed time procedure under optimum reaction conditions where the change in absorbance (DeltaA(t)) versus ruthenium(III) concentrations is plotted. The calibration curve recommended for the method is linear in the concentration range 10.11-252.67ngml(-1) with very good accuracy and reproducibility and a maximum error 2.20%. The detection limits of the method for ruthenium(III) corresponding to 10, 15 and 20min are 8.02, 5.03 and 3.15ngml(-1), respectively. The ruthenium(III) has also been determined in the presence of several other interfering and non-interfering cations and anions and no foreign ions interfered in the determination of ruthenium(III) up to five-fold higher concentration of the foreign ions tested. The method is highly sensitive, selective and stable. It has successfully been applied for the determination of trace ruthenium(III) in some synthetic and environmental water samples. A review of most of the published catalytic kinetic and some other important methods for the determination of ruthenium has also been presented.     

Simultaneous Determination of Copper (II) and Mercury (II) by Using a Zero-Crossing Method

Abstract

The application of a zero-crossing method to the simultaneous determination of copper (II) and mercury (II) with methylethylenediaminetetraacetic acid (MEDTA) is described. The procedure does not require equations to be solved, and it is suitable for concentrations of 0.008–0.036 mg ml^?1 of copper and 0.025–0.300 mg ml^?1 of mercury. The main interferences, both anionic and cationic, were easily eliminated. The method was applied to different aqueous matrices. It was compared with an atomic absorption spectrophotometry method (AA) and good results were obtained.     

微波消解-石墨炉原子吸收光谱法测定鱼肉和河蚌中的重金属

建立微波消解样品,石墨炉原子吸收光谱法测定鱼肉和河蚌中重金属Pb,Cd,Cr,Cu,Ni含量的方法。优化了石墨炉原子吸收光谱法测定条件,在最佳实验条件下,选用磷酸二氢铵作为Pb,Cd,Cr,Cu的基体改进剂,抗坏血酸作为Ni的基体改进剂。Pb,Cd,Cr,Cu,Ni的检出限分别为0.05,0.01,0.05,0.05,0.07μg/g,实际样品测定结果的相对标准偏差为6.3%~14.5%(n=6),加标回收率为84.5%~113.0%。测定了牡蛎标准参考样,测定值在标准值可接受范围内。该方法检出限低、准确度高,适用于鱼类、河蚌样品中重金属含量的分析。     

Determination of arsenic in mussels by slurry sampling and electrothermal atomic absorption spectrometry (ETAAS)

A method for the determination of arsenic in slurries of mussel tissue using palladium-magnesium nitrate as modifier was optimized. The slurry was stabilized by a 0.015% (v/v) of Triton X-100. To achieve complete mineralization the slurries were ashed at 480 °C for 10s in an air flow (50 ml/min) and at 1200 °C for 15s in an argon flow (300 ml/min) in the presence of Pd—Mg(NO₃)₂ as modifier. The optimum atomization temperature was 2200 °C. The precision and accuracy of the method were studied using the Reference Material BCR n ° 278 Mussel Tissue (Mytilus edulis). The detection limit (LOD) of the final slurry solution was 1 g/l of arsenic corresponding to an arsenic level in the mussel of 1.3 g/g, for a 0.5% (m/v) slurry. Results of calibration using aqueous standards and the standard additions method were compared. The method was applied to the determination of arsenic in mussels from the Galician coast. The levels found lie between 2 and 9.3 g/g of arsenic.     

湿法消解-电感耦合等离子体质谱(ICP-MS)法测定大气降尘中7种重金属

为精准防控大气降尘污染,提供其重金属检测方法。重点考察了样品前处理中混合酸体系选择和最佳酸用量比对实验。在最优条件下建立了混合酸（硝酸、氢氟酸、盐酸和高氯酸）湿法消解大气降尘样品和电感耦合等离子体质谱仪进行7种重金属（铊、铅、镉、铬、铜、锌和镍）含量测试的实验方法。实验结果显示7种重金属在一定的浓度范围内线性关系好,线性系数均大于0.999,7种重金属方法检出限为0.02 mg/kg～2.0 mg/kg,实际样品6次测定相对标准偏差为1.1 %～5.7 %,加标回收回收率为87.7 %～108.9 %。该方法经济环保、准确快捷,可作为大气沉降重金属检测参考方法。     

Determination of trace arsenic in hydrofluoric acid by hydride generation and atomic absorption spectrometry

Practical procedures are given for determination of arsenic(III) and (V) in hydrofluoric acid by means of hydride generation and atomic absorption spectrometry. Arsenic(III) can be determined by direct generation of arsine with sodium borohydride in hydrochloric/hydrofluoric acid medium, arsenic(V) being only slightly reduced under the conditions used. For its determination, arsenic(V) has to be prereduced with potassium iodide, and even then its reduction to arsenic(III) and then arsine is far from complete. It is possible to determine it in presence of arsenic(III) by a difference method, but this is recommended only if the As(V)/As(III) ratio is greater than 1. Total arsenic can be determined after oxidation of As(III) and evaporation of most of the hydrofluoric acid. The limit of determination is 5 g/l for arsenic(III) and 0.25 g/l for total arsenic; the relative standard deviation is about 10%.     

Spectrophotometric Determination of Iron(III) as Azide Complexes in Aqueous Tetrahydrofuran

Abstract

A simple, sensitive and alternative method for the spectrophotometric determination of iron(III) has been established. The procedure is based on the formation of iron-azide complexes in 60% (v/v) tetrahydrofuran/ water medium. The high sensitivity obtained in this method is due to the use of an interesting absorption band not previously reported in the literature. In the recommended conditions, absorbances for the ferric complexes are measured at 400 nm where the molar absorptivity is 1.52 × 10⁴ 1 mol^?1 cm^?1. The organic solvent used increases the sensitivity and the stability of the measurements. The precision is shown by the average deviation of about 0.3%. This system obeys Beer's law and is suitable for iron(III) determination in the concentration range from 0.6 to 3.2 mg 1^?1 (ppm). The best experimental conditions were determined studying the different factors involved. The influence of various diverse ions was also studied.     

固相萃取-电感耦合等离子体原子发射光谱（ICP-AES）法测定地下水中三种重金属

为拓宽固相萃取技术在生态环境监测领域应用范围,建立了树脂固相萃取前处理ICP-AES法测定地下水中铅、铬、镉含量的方法。经前处理条件优化,硝酸洗脱液浓度5%、缓冲溶液pH 7、洗脱速率10 mL/min及进样体积为500mL条件下,铅、铬、镉等三种重金属回收率均可以达到95%以上。该方法中各目标元素在0.02~20 μg/L范围内线性关系良好,相关系数均大于0.999;铅、铬、镉方法测定下限分别0.56μg/L,0.04μg/L,0.24μg/L满足评价要求;方法精密度RSD值在0.44%~5.49%;加标回收率范围分别在98.55%~101.84%、98.5%~104%、95.5%~105%。经监测井实样测试,铅、铬、镉结果处于《地下水质量标准》（GB/T14848-2017）I类限值范围内。该方法干扰小,易操作,为相关国家标准修订提供参考。     

Determination of Residues of Furadan (Carbafuran) in Water by Spectro-Photometric Method

Abstract

A spectrophotometric method for the determination of carbafuran residues in field water using eerie sulphate as a reagent has been worked out.     

Determination of major and trace elements in biological materials by microwave induced plasma optical emission spectrometry (MIP-OES) following tetramethylammonium hydroxide (TMAH) solubilization

A simple, alternative method to acid digestion is presented for the preparation of biological materials for major and trace elements by microwave induced plasma optical emission spectrometry (MIP-OES). Standard reference materials were solubilized using a methanolic solution of tetramethylammonium hydroxide (TMAH) by the application of ultrasonic agitation. Following dilution with water suspensions were pumped to a V-groove Babington-type nebulizer then into argon plasma. Limits of detection and precision are reported for major (Na, K, Ca, Mg) and trace (Cu, Fe, Sr, Zn) elements. Standard addition procedures were used to minimize possible matrix interferences. The method offers relatively good precision (R.S.D. ranged from 6 to 12%). Measured concentrations are in satisfactory agreement with certified values for the biological reference materials: TORT-1 (Lobster hepatopancreas), IAEA-153 (Milk powder) and NIST 1577 (Bovine liver). The simple procedure could be useful as a routine analysis of biological materials.     

Trace analysis of toxic metals,III. Determination of chromium as trivalent chromium by differential pulse polarography

Methods for trace analysis of chromium as Cr³⁺ were investigated, using differential pulse polarography in various media. Determination at the ng/ml-g/ml range can be carried out in KCl/HCl, KCNS/HOAc, and other media. Total concentration of chromium in a solution containing Cr³⁺ and HCrO ₄ ^– can be determined in KCNS/HOAc, and it is found that HCrO ₄ ^– can be converted quantitatively to Cr³⁺. The relative quantity of HCrO ₄ ^– and Cr³⁺ can be determined by the difference between the total chromium concentration and the concentration of HCrO ₄ ^– . The sensitivity (12.5 ng/ml) and accuracy of this method is better than the method that determines total chromium as HCrO ₄ ^– .     

Admicelle-mediated collection followed by flotation for the preconcentration of trace metals in fresh waters

Dithizone-impregnated admicelles were prepared by mixing silica particles with dithizone and cetyltrimethylammonium chloride in 0.1 mol L⁻¹ aqueous ammonia. The resulting admicelles were added to 1000 mL of sample solution and dispersed by stirring for 15 min. Traces of Ni(II), Cu(II), Ga(III), Cd(II), Pb(II) and Bi(III) in the solution were simultaneously incorporated into the admicelles at pH 7.5-9. With the aid of a rising stream of numerous tiny bubbles, the admicelles were floated on the solution surface and collected in a small sampling vessel by suction. The metals were desorbed from the admicelles with dilute nitric acid and determined by inductively coupled plasma-mass spectrometry. The proposed method offered a 100-fold multielement preconcentration and it was applicable to the analysis of river and pond waters.