Determination of silica in geological materials by atomic absorption spectrometry

A simple rapid method for the routine determination of silica by atomic absorption spectrometry (a.a.s.) in a wide range of geological materials is described. Samples are decomposed by heating with hydrofluoric acid in closed containers and diluted gravimetrically. Large concentrations of free hydrofluoric acid are tolerated and the resulting solutions show excellent stability. No chemical interference was identified in the atomic absorption measurements. The technique was extended to the micro-determination of silica in samples of milligram size as well as trace-level silicon in waters. The average standard deviation is ?1% by the recommended method, 2.6% by the micro-method and 2–6% at trace level (20–0.5 ppm Si), respectively. The procedure described complements the a.a.s. scheme in current use for some 25 major and trace elements.     

Determination of total tin in geological materials by electrothermal atomic absorption spectrometry

A graphite-furnace atomic-absorption spectrometric method is described for the determination of total tin in geological materials. Samples are decomposed by fusion with lithium metaborate and the melt is dissolved in diluted (1 + 9) nitric acid. Spectral and non-spectral interferences are minimized by a combination of platform volatilization, “normal” heating rate, addition of ammonia as chemical modifier, use of integrated absorbance values and Zeeman background correction. Results are reported for six reference materials showing good accuracy and a precision of 12% at the 3 μg g^?1 level. The detection limit for tin in the original materials in 0.7 μg g^?1.     

微型氢化物发生-原子吸收光谱法测定纺织品中的痕量砷和锑

采用三毛细管微型在线氢化发生技术和装置, 建立了氢化物发生-电热石英管原子吸收法测定纺织品中痕量As、 Sb的分析方法. 研究了共存离子对As、 Sb检测的干扰及消除方法. 结果表明: 该方法除Co、 Sn对As和Ni对Sb有干扰外, 其它干扰元素允许量都较大. 采用酒石酸和KI混合掩蔽剂可抑制Co、 Sn对As和Ni对 Sb的干扰. As和Sb的检出限分别为0.7和0.4 ng/L, 已用于测定纺织品中痕量As和Sb的分析.     

Determination of thallium in geological materials by extraction and electrothermal atomic absorption spectrometry

Thallium is determined in geological reference materials by acid digestion, extraction of thallium(III) from 0.5 M HBr solution into methyl isobutyl ketone and direct electrothermal atomic absorption spectrometry. The method yields results that agree with published values, has a detection limit of 0.04 μg Tl g^-1, and is relatively free of interferences.     

电沉积-钨丝电热原子吸收光谱法测定地质样品中痕量金

以市售幻灯投仪卤钨灯泡钨丝为原子化器的钨丝电热原子吸收光谱分析仪(TC-AAS),功率小、仪器成本低[1,2],如用微型CCD光谱仪作检测系统,可以实现原子吸收光谱仪的小型化,甚至可用于野外现场分析[3,4].     

Determination of trace amounts of scandium by atomic absorption spectroscopy

Optimum instrumental conditions were investigated for the determination of trace quantities of scandium by atomic-absorption spectroscopy. Enhancement effects by organic solvents and by complex extractions were also studied. (46)Sc was used to establish the optimum extraction conditions. A sensitivity of 0.06 ppm of Sc was observed when using extraction into oxine-butanol and atomic absorption was measured with an acetylene-nitrous oxide flame.     

Determination of trace amounts of chromium by atomic absorption spectrometry with a tantalum filament atomizer

The sample solution containing chromium was vaporized and atomized from a tantalum filament by electrical heating into an argon stream within an absorption chamber. The interference of various metals on the atomic absorption spectrometry of chromium was investigated. Interferences were minimized by using a high filament temperature. The flameless atomizer was used for the determination of chromium in steel at a filament temperature of 2150°; with the steels investigated no matrix effect was observed, and the accuracy and precision were satisfactory.     

Determination of antimony by using tungsten trap atomic absorption spectrometry

An electrically heated tungsten coil was used as a trap in the determination of antimony. The technique consists of three steps. Initially, SbH₃ is formed by hydride generation procedure; then the analyte species in vapor form are transported to W-coil trap heated at 370 °C. Following the preconcentration step, the trap is heated to 895 °C; analyte species are revolatilized and transported to the flame-heated quartz atom cell where atomization and the formation of signal take place. The experimental parameters were optimized both for trap and no-trap studies. The most important experimental parameters are concentrations of HCl and NaBH₄ solutions, H₂ and Ar gas flow rates, and collection and revolatilization temperatures of W-coil. Accuracy was tested using a certified reference material, waste water EU-L-1. Limit of detection for the system is 16 ng l^− 1 using a sample of 36 ml collected in 4.0 min. Enhancement factor in sensitivity was 17.     

Determination of lead in geological and biological materials by graphite furnace atomic absorption spectrometry

Summary Serious systematic errors inherent in the determination of lead in geological and biological samples by flameless atomic-absorption spectrometry are demonstrated. The reduced absorption of lead is due to partial interaction with alkaline, alkaline-earth and iron chlorides during the atomization stage. Incomplete dissociation of the volatile monochloride of lead in the gaseous phase reduces the absorption signal. An addition of 20% hydrogen to nitrogen (purge gas) diminishes signal suppression by removing the chlorine in form of volatile HCl. The detection limit is about 0.6 ppm in rocks and about 0.3 ppm in plant materials. Depending on the content in the samples the relative standard deviation is between 1 and 12%. The accuracy of the method was tested on 39 international standard reference samples.

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Bestimmung von Blei in geologischen und biologischen Materialien durch AAS mit der Graphitrohrküvette

Zusammenfassung Schwerwiegende systematische Fehler bei der Bestimmung von Blei in geologischen und biologischen Materialien mit der Graphitrohrküvette werden aufgezeigt. Die Reaktion von Blei mit Alkali-, Erdalkali- und Eisenchloriden während der Atomisierungsphase führt zur Bildung von Bleimonochlorid, das nur unvollständig dissoziiert und eine Signalunterdrückung zur Folge hat. Ein Zusatz von 20% Wasserstoff zu Stickstoff als Spülgas vermindert die Signalunterdrückung, indem überschüssiges Chlor als Chlorwasserstoff entfernt wird. Die Nachweisgrenze liegt bei ca. 0,6 ppm für Gesteine und bei ca. 0,3 ppm für Pflanzenmaterialien. Je nach der Konzentration beträgt die relative Standardabweichung 1–12%. Die Genauigkeit der Methode wurde an 39 internationalen Standardreferenzproben überprüft.

     

Determination of ultra trace amounts of cobalt in fish by graphite furnace Zeeman effect atomic absorption spectrometry

A method is described for determining stable cobalt concentrations in fish flesh and bone using polarized Zeeman effect graphite furnace atomic absorption spectrometry (ZAAS). Cobalt analysis on freshwater fish flesh samples (10 g dry weight) required predigestion and wet-ashing at 70-80 degrees C. Cobalt is chelated with ammonium pyrrolidine dithiocarbamate (APDC) extracted with methyl isobutyl ketone (MIBK) and analysed by ZAAS. The mean cobalt content calculated from the standard additions method using three replicate fish flesh samples was 4.23 +/- 1.0 microgram Co. Kg-1 (dry weight). Analyses were also carried out on flesh and bone samples from similar sized fish, of the same species, taken from three area lakes.     

Determination of bismuth in geological materials by automated hydride generation and electrothermal atomic absorption spectrometry

The rapid and precise determination of bismuth (>5 μg kg^?1 in geological materials is described. The sample is decomposed with a HClO₄/HNO₃/HF mixture; interferences are eliminated by addition of aluminium chloride, ascorbic acid and thiourea. Bismuth hydride is introduced into a quartz cell atomizer.     

Arsine generation and determination of trace amounts of arsenic by atomic absorption spectrometry

Arsenic can be determined by atomic absorption spectrometry after reduction to arsine with potassium iodide, tin(II) chloride and zinc powder tablet; the arsine generated is carried into an argon-hydrogen flame by means of argon. Accuracy, precision and speed are satisfactory. Serious interferences arise only from nitric acid, lead, chromium and selenium.     

Determination of trace amounts of cadmium by modified graphite furnace atomic absorption spectrometry after liquid phase microextraction

A simple and powerful microextraction technique was used for determination of cadmium in water samples using liquid phase microextraction (LPME) followed by graphite furnace atomic absorption spectrometry (GF-AAS). In a preconcentration step, cadmium was extracted from a 2 mL of its aqueous sample in the pH = 6 as cadmium-2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP) cationic complex into a 4 µL drop of nitrobenzene and ammonium tetraphenylborate as counter ion. In the drop, the cadmium-2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP) ammonium tetraphenylborate ion associated complex was formed. After extraction, the microdrop was retracted and directly transferred into a graphite tube modified by [Pd_(c) + Pd_(i)]. Some effective parameters on extraction and complex formation, such as type and volume of organic solvent, pH, concentration of chelating agent and counter ion, extraction time and stirring rate were optimized. Under the optimum conditions, the enrichment factor and recovery were 390 and 78%, respectively. The calibration graph was linear in the range of 0.01–1 µg L^− 1 with correlation coefficient of 0.9952 under the optimum conditions of the recommended procedure. The detection limit based on the 3Sb criterion was 0.0065 µg L^− 1 and relative standard deviation (RSD) for eight replicate measurements of 0.1 µg L^− 1 and 0.4 µg L^− 1 cadmium was 6.4 and 5.8% respectively. The characteristic concentration was 0.0014 µg L^− 1 equivalent to a characteristic mass of 5.6 fg. In order to evaluate the accuracy and recovery of the presented method the procedure was applied to the analysis of reference materials and seawater.     

The determination of cadmium in geological materials by flameless atomic absorption spectrometry

The use of graphite-furnace atomic absorption spectrometry for the determination of cadmium in rocks and sediments by direct atomization from the solid state is described. At the 10–1000 p.p.b. level, the relative standard deviation is ± 10–20 %. Samples were ground to 100 mesh and, if necessary, 325 mesh before analysis. Two resonance lines were employed: 228.8 nm for less than 5 p.p.m. cadmium and 326.1 nm for levels above 5 p.p.m. Instrumental parameters were optimized to produce maximum peak heights. Results are given for a series of standard rocks and for stream sediment samples.     

Determination of trace mercury in geological samples by direct slurry sampling cold vapor generation atomic absorption spectrometry

A new method based on ultrasonic slurry sampling atomic absorption spectrometry (AAS) was established for the determination of trace mercury in geological samples by use of recently developed mercury cold vapor generation using formic acid under ultraviolet (UV) irradiation. The generated mercury cold vapor was rapidly separated from the matrix and swept into a T-tube for the measurement of atomic absorbance. Under the optimal experimental conditions, up to 1000-fold of Cu(II), Co(II), Ni(II), Cr(VI), Mn(II), Fe(III), and Zn(II) caused no significant interference with the determination of 50 μg L⁻¹ Hg. The limit of detection at sub-ppb level was obtained for mercury. The method was applied to the determination of mercury in geological samples with satisfactory results. Correspondence: Xiandeng Hou, College of Chemistry, Sichuan University, Chengdu, Sichuan 610064, China     

Determination of trace metals in sodium by electro-thermal atomic absorption spectrometry

Graphite-furnace atomic absorption spectrometry is used to analyze sodium metal after conversion to sodium nitrate. Chromium, Ni, Co, Cd and Pb have detection limits in sodium of 0.18, 0.48, 0.11, 0.02 and 0.48 μg g^-1; these are similar to the concentrations in nuclear-grade sodium, except for lead, which is below the detection limit. The behaviour of sodium nitrate, chloride and sulphate as matrices is compared.     

Determination of indium in geological materials by electrothermal-atomization atomic absorption spectrometry with a tungsten-impregnated graphite furance

The sample is fused with lithium metaborate and the melt is dissolved in 15% (v/v) hydrobromic acid. Iron(III) is reduced with ascorbic acid to avoid its coextraction with indium as the bromide into methyl isobutyl ketone. Impregnation of the graphite furnace with sodium tungstate, and the presence of lithium metaborate and ascorbic acid in the reaction medium improve the sensitivity and precision. The limits of determination are 0.025–16 mg kg^?1 indium in the sample. For 22 geological reference samples containing more than 0.1 mg kg^?1 indium, relative standard deviations ranged from 3.0 to 8.5% (average 5.7%). Recoveries of indium added to various samples ranged from 96.7 to 105.6% (average 100.2%).     

原子吸收光谱法测定苦藠中微量元素的含量

苦藠别名小野蒜是食用地下鳞茎及嫩茎叶的野生蔬菜,属药食同源的百合科多年生草本植物.有温中散结,宽胸通阳,祛湿止痢作用~([1,2]).在食疗方面有:(1)降脂作用,且性味辛温,能温阳散结,可用来治疗高胆固醇和高血脂症.(2)降低血压的奇妙作用,常食有通阳气、宽胸的效果.