Direct atomic absorption spectrometric determination of copper,nickel and vanadium in coal and petroleum coke

The solid sampling technique is used to determine copper, nickel and vanadium in coals and a petroleum coke. The National Bureau of Standards SRM 1632a, Trace Elements in Coal, and aqueous solutions of the elements were employed as standards. The contents of copper, nickel and vanadium were in the ranges 1–17, 3–130 and 20–140 ppm, respectively.     

浊点萃取-火焰原子吸收光谱法测定淡水鱼中痕量铅

采用以双硫腙为络合剂、Triton X-100为表面活性剂的新型浊点萃取体系富集淡水鱼中的痕量铅,并用火焰原子吸收光谱法对其进行测定。探讨了溶液pH、表面活性剂浓度、络合剂用量、平衡温度、平衡时间等对浊点萃取及测定灵敏度的影响,优化了实验条件。在最佳条件下测得铅的检出限为0.090μg/L,校准曲线相关系数为0.9999。该方法已用于淡水鱼中痕量铅的测定。     

Electrothermal atomic absorption spectrometric determination of copper and zinc in high-purity bismuth after thiocyanate extraction

Copper and zinc (0.01–1 μg g^?1)in high-purity bismuth are extracted together as their thiocyanate complexes into methyl isobutyl ketone and determined by atomic absorption spectrometry with a tungsten-strip atomizer. The concentrations of copper found by the proposed method agree well with the values obtained by similar atomic absorption spectrometric methods involving prior extraction of copper as its bathocuproine or diethyldithiocarbamate complex.     

Indirect atomic absorption spectrometric determination of perchlorate by liquid-liquid extraction in a flow-injection system

The determination is based on the continuous liquid-liquid extraction of the copper(I)/6-methylpicolinealdehyde azine/perchlorate ion-pair into 4-methyl-2-pentanone in a flow-injection manifold. The organic fills a loop of an injector situated in an integrated feed system of an atomic absorption spectrometer. Measurement of the copper atomic absorption signal from the organic phase allows the indirect determination of 0.5–5 μg ml^?1 perchlorate, giving a 3-fold increase in sensitivity over the conventional spectrophotometric method. The detection limit is 70 ng ml^?1. The sampling frequency is 45 ± 5 h^?1. The method is highly selective, and has been used for the determination of perchlorate added to serum and urine samples.     

The determination of magnesium in silicates by atomic absorption spectroscopy

The determination of magnesium in silicates by atomic absorption spectroscopy using a hot flame is discussed. Interference by aluminium observed, in the air-acetylene flame is overcome by using the hotter nitrous oxide-acetylene flame. There is some evidence to suggest that the alkali metals interfere in this determination but this is not confirmed in the results obtained on standard rock samples. Values for magnesium are given for some new rock standards recently distributed by the U.S. Geological Survey.     

Indirect determination of vanadium by atomic absorption spectrometry

An indirect method for the determination of vanadium as vanadate by atomic absorption spectrometry is described. In neutral medium, vanadate forms a stable ion-association complex with copper (II) and biguanide, which is extractable into butanol with an efficiency higher than 99%. The copper content in the extract (and hence indirectly VO^?₃) is determined by aspirating it directly into an acetylene flame. The calibration graph is linear up to 3.4 μg ml^?1 of VO^?₃. The limit of detection is 16 ng ml^?1. Only chromium interferes.     

Electrothermal atomic absorption spectrometric method for the determination of vanadium in diesel and asphaltene prepared as detergentless microemulsions

A method based on electrothermal atomic absorption spectrometry for the determination of vanadium in diesel and asphalthene fractions is proposed. In order to avoid analyte losses observed at the microgram per liter range for metal traces in organic solutions, diesel samples were stabilized as detergentless microemulsions by mixing with propan-1-ol and nitric acid solution. The solid asphaltene oil fraction was separated and dissolved in dichloromethane before mixing these solution with propan-1-ol and nitric acid solution. Wall atomization as well as no modifier was used. For diesel, aqueous analytical solutions could be used for calibration. For asphaltene, calibration was performed with analytical solutions prepared at the dichloromethane+propan-1-ol+nitric acid medium, spiked with inorganic standard solution. Linear ranges up to 200 μg l⁻¹ were observed, as well as limit of detection of 5 μg l⁻¹ and 4 μg g⁻¹ for diesel and asphaltene, respectively. Good recoveries were obtained for V-cyclohexanebutyrates spiked diesel samples, as well as coherent results for the asphaltene fraction of the NIST 1634c (trace elements in fuel oil) certified reference material.     

Direct electrothermal atomic absorption spectrometric determination of selenium in serum

The effect of copper, iron, nickel and silver ions on the thermal stability of inorganic and metabolized forms of selenium in serum was studied with radioactive ⁷⁵Se. Copper and iron had no stabilizing effect but in the presence of nickel or silver the temperature could be raised to 1050°C or 1250°C, respectively, without loss of selenium. On this basis an electrothermal atomic absorption spectrometric method was developed for the direct determination of selenium in human serum; selenium is stabilized with nickel during ashing. In 12 samples of sera from unexposed individuals, the concentrations ranged from 92 pob to 140 ppb. The relative standard deviation of the method is 4%, and the detection limit is 5 ppb.     

Flow injection wetting-film extraction system for flame atomic absorption spectrometric determination of cadmium in environmental waters

A newly simple flow injection wetting-film extraction system coupled to flame atomic absorption spectrometry (FAAS) has been developed for trace amount of cadmium determination. The sample was mixed on-line with sodium diethyl dithiocarbamate and the produced non-charged Cd(II)-diethyl dithiocarbamate (DDTC) chelate complex was extracted on the thin film of diisobutyl ketone (DIBK) on the inner wall of the PTFE extraction coil. The wetting-film with the extracted analyte was then eluted by a segment of the cover solvent, and transported directly to the FAAS for evaluation. All the important chemical and flow parameters were optimized. Under the optimized conditions an enhancement factor of 35, a sample frequency of 22 h⁻¹ and a detection limit of c_L = 0.7 μg l⁻¹ Cd(II) were obtained for 60 s preconcentration time. The calibration curve was linear over the concentration range 1.5-45.0 μg l⁻¹ Cd(II) and the relative standard deviation, R.S.D. (n = 10) was 3.9%, at 10.0 μg l⁻¹ concentration level. The developed method was successfully applied to cadmium determination in a variety of environmental water samples as well as waste-water sample.     

Electrothermal atomic absorption spectrometric determination of aluminum in blood serum

An aerosol-generating device is used for sample application. Precision ranges from 2.5 to 8.0% and recoveries of 30 and 100 μg l^-1 added to each of five samples ranged from 95 to 105%. Correlation with a slightly different method gave a least-squares fit of y = 1.02x – 1.35 μg l^-1. The technique described is satisfactory for studying aluminum toxicity in dialysis encephalopathy and Alzheimer's Disease.     

Sequential atomic absorption spectrometric determination of nitrate and nitrite in meats by liquid-liquid extraction in a flow-injection system

Sequential determinations of nitrate and nitrite based on continuous liquid-liquid extraction, and suitable for their routine determinations in meats, are reported. Nitrate reacts with bis(2,9-dimethyl-1,10-phenanthrolinato)copper(I) to form an ion-pair which is extrated into 4-methyl-2-pentanone in a flow-injection manifold. In one aliquot of sample, nitrite is oxidized by cerium(IV), so that total nitrate is determined. In another, nitrite is converted to nitrogen with sulfamic acid, so that only the original nitrate is determined. By measuring the atomic absorption signal of copper in the organic phase, mixtures of these anions can be determined at μg ml^?1 levels for nitrate/nitrite ratios from 10:1 to 1:10, with a sampling frequency of ca. 20 h^–1.     

Flow injection on-line hydrophobic sorbent extraction for flame atomic absorption spectrometric determination of cadmium in water samples

A flow injection system was developed for on-line sorbent extraction preconcentration and flame atomic absorption spectrometric determination of cadmium in natural water samples. The non-charged cadmium complex with diethyl-dithiophosphate (DDPA) was formed on-line in 0.1 mol L⁻¹ HNO₃ and retained on the hydrophobic poly-chlorotrifluoroethylene (PCTFE) sorbent material. The adsorbed complex was eluted with isobutyl methylketone (IBMK) and injected directly into the nebulizer via a flow compensation unit. All major chemical and flow parameters affecting the complex formation adsorption and elution as well as interference were studied and optimized. By processing 2.4 mL of sample, the enhancement factor was 39 and the sampling frequency was 50 h⁻¹. For 30 s preconcentration time the detection limit was 0.3 μg L⁻¹ and the relative standard deviation at 5.0 μg L⁻¹ Cd concentration level was 2.9%. The calibration curve was linear in the range 0.8–40.0 μg L⁻¹. The accuracy of the method was estimated by analyzing a certified reference material NIST-CRM 1643d (Trace elements in water). Good recoveries were obtained for spiked natural-water and waste-water samples. Correspondence: Aristidis N. Anthemidis, Laboratory of Analytical Chemistry, Department of Chemistry, Aristotle University, GR-Thessaloniki 54124, Greece     

Flame atomic absorption spectrometric determination of cadmium and copper in biological reference materials using on-line sorbent extraction preconcentration

Summary Cadmium and copper at the g/g to ng/g level in plant and animal tissue reference materials, and at the g/l level in urine were determined by flame atomic absorption spectrometry using on-line sorbent extraction preconcentration based on flow injection techniques. Bonded silica reversed phase sorbent with octadecyl functional groups (RP-C 18), packed in a 100 l column, was used to collect the diethylammonium-N,N-diethyldithiocarbamate (DDTC) complex formed on-line in the sample digests at low pH. Methanol was used to elute the analyte chelates directly into the nebulizer-burner system of the spectrometer. Small air segments introduced before and after elution prevented the eluent from mixing with the sample solution and increased the sensitivity. A sampling frequency of 85/h could be obtained with a sample loading time of 30 s at a flow rate of 4.0 ml/min. The enrichment factor for both elements was 20 and the enhancement factors, including the effect of the organic solvent and with the flow spoiler removed, were 126 and 114 for cadmium and copper, respectively. The detection limits (3) were 0.15 g/l for cadmium and 0.2 g/l for copper. The precision was 2.3% and 1.4% r.s.d. for 10 g/l Cd and 45 g/l Cu, respectively (n=11). Results for the determination of cadmium and copper in various biological reference materials were typically in good agreement with certified values. Low recoveries were observed, however, for cadmium in samples containing high levels of copper and/or iron, such as bovine liver.On leave from Flow Injection Analysis Research Center, Institute of Applied Ecology, Academia Sinica, Shenyang, China     

Graphite furnace atomic absorption spectrometric determination of iridium,rhodium and ruthenium in high-purity platinum after matrix extraction

Ir, Rh and Ru are separated from a large excess of platinum by extraction with isoamyl alcohol-isobutyl methyl ketone mixture. Graphite furnace atomic absorption spectrometry using the method of standard addition is then used to determine the metals with satisfactory precision and accuracy.     

Flow-injection preconcentration and graphite furnace atomic absorption spectrometric determination of platinum

Flow-injection graphite furnace atomic absorption spectrometric (GFAAS) methods were worked out using oxime, sulphoxine and 2,2′-diamino-diethylamine (DEN) cellulose microcolumns for preconcentration of platinum after reduction by iodide or sulphite ions. The detection limits were, at 20-fold enrichment, 0.21, 0.18 and 0.30 μg l⁻¹, respectively. The total reflection X-ray fluorescence spectrometry (TXRF) was also used for the determination of platinum in eluates. The method was applied for the determination of platinum in salmeterol xinafoate and Ca-folinate pharmaceutical compounds. Decomposition of organic matrix of Ca-folinate was necessary before the preconcentration.     

Indirect atomic absorption spectrometric method for the determination of silicon

Summary An indirect atomic absorption Spectrometric method for the determination of silicon is proposed which is based on the precipitation of an equivalent amount of lead molybdate from solutions treated with a known excess of lead ion and subsequent measurement of the lead ion remaining in solution. A typical calibration graph is linear for samples containing 0.5–7g silicon.

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Zusammenfassung Eine indirekte Siliciumbestimmungsmethode durch Atomarabsorption wurde vorgeschlagen. Sie beruht auf der Fällung einer äquivalenten Menge Bleimolybdat aus Lösungen mit einem bekannten Überschuß von Bleiionen und nachfolgender Messung des Bleis im Filtrat. Die Eichkurve für Proben mit 0,5 bis 7g Silicium ist linear.

     

Extraction and atomic absorption spectrometric determination of bismuth with electrothermal atomization

Summary A sensitive method for the extraction and atomic absorption spectrometric measurement with electrothermal atomization has been developed for the determination of bismuth in tea and orchard leaves. Bismuth is extracted into m-xylene as diethyldithiocarbamate complex. 2.5–3.0 l/min of argon flow rate, 650–800° C of ashing temperature and 2,200–2,600° C of atomization temperature were the best experimental conditions. A detection limit of 0.02 ng was obtained with a precision of 2–7% and minimal interference effects.Paper read at the meeting of the Japan Society for Analytical Chemistry, October 1978     

Graphite furnace atomic absorption spectrometric determination of ruthenium in iron meteorites

A procedure for the determination of ruthenium in iron meteorites involves its oxidation to RuO₄ by sodium periodate in hydrochloric acid and extraction of the tetroxide into chloroform. Various parameters of the method were studied: sample dissolution, optimum amount of oxidant, shaking time, distribution ratio and stability of the complex. The relative standard deviation assessed from replicate analyses of the North Chile iron meteorite was 6.6%. There are no certified standards for iron meteorites, but the value of 20.0 μg g^? obtained for this meteorite compares well with a reported abundance of 19.3 μg g^?1 obtained by radiometric neutron-activation analysis (RNAA). The analysis of 15 meteorites that had previously been analysed by RNAA gave values averaging 11% below those reported by the latter method, but within the standard deviation of the RNAA data. It is considered that the present method is a more practical alternative to RNAA for the determination of ruthenium in iron meteorites.     

Solid phase extraction and graphite furnace atomic absorption spectrometric determination of ultra trace amounts of bismuth in water samples

A simple and reliable method for the selective extraction and determination of bismuth in water as well as alloy samples using octadecyl bonded silica cartridge modified with cyanex 301 and graphite furnace atomic absorption spectrometry is described. Extraction efficiency and influence of sample matrix, optimum amount of extraction ligand, type and least amount of proper eluent and flow rates were evaluated. The limit of detection of the proposed method is 0.01 ng ml(-1). The influence of potential interfering cations in water samples on the recovery of bismuth was investigated. The method was successfully applied to the extraction and determination of bismuth in natural water and alloy samples.