Determination of heavy metals in sea water and in marine organisms by flameless atomic absorption spectrophotometry

Summary This publication is a part of a series in which the author describes a set of methods for the determination of cadmium in environmental samples by means of flameless AAS. Common properties of these methods are their miniaturization and standardization. These have been attained by the utmost reduction of the number of steps and by their simplification. The method described in this publication consists of an acid digestion procedure followed by neutralization, extraction, and flameless AAS measurement. The main characteristics are: digestion takes place in small 1.5 ml tubes of quartz, polyvinyldifluoride or polypropylene. Neutralization is not performed by titration but only by an excess of saturated NaHCO₃ solution. Extraction results are independent of pH in the region to be expected. Extraction is carried out by a (stable) solution of APDC in CCl₄. The organic extract is also stable for at least 16h. Precision of the method lies in the range of 8.4%, at a concentration of 18.9 ng Cd g^–1; sensitivity is at least in the range of 1.2 ng Cd g^–1. The latter can be increased, if necessary, by a several-step extraction procedure.Teil VIII: Z. Lebensm.-Unters. Forsch. 168, 193-194 (1979)     

Determination of heavy metals in sea water and in marine organisms by flameless atomic absorption spectrophotometry

Summary This paper presents results of an intercalibration of cadmium determination by means of flameless AAS in biological materials from toxicological experiments. Furthermore, the philosophy of this kind of investigation is discussed in some detail. The goal and the result of this investigation was a correspondence of the measurement results within an acceptable range. Contamination during further handling has been identified as the main reason for severe deviations. The authors made measurements in the labs of several colleagues. The equipment itself did not produce individual variations. Repeated intercomparison after elimination of identified systematic errors showed sufficient correspondence of the results.Teil XII: Fresenius Z. Anal. Chem.301, 294–299 (1980)     

Determination of heavy metals in sea water and in marine organisms by flameless atomic absorption spectrophotometry

Summary In natural waters, heavy metals such as Cd may be present in bound form. It is, therefore, important to consider chemical speciation, especially at low concentrations of the metal where a significant part can be bound by other trace constituents so tightly that it escapes several forms of its determination. It has been demonstrated that even the very strong complexant APDC is unable to leach out all of the heavy metal present in several coastal water samples from the German Bight.This paper describes a new micro method for the determination of total Cd in natural waters. First a small sample is dried in a polypropylene vial. Then the salt residue is heated to 90° C with a mixture of sulphuric and nitric acid for digestion of organic trace constituents (and oxidation of sulphides if present). After dilution subsamples are neutralized using an excess of NaHCO₃ buffer solution. Extraction results are then independent from the possible slight variations of pH. The extractant, a solution of APDC in CCl₄ is stable for weeks, and even the extract is stable for at least 16h. Precision is in the range of 7% at a concentration of 0.066 g Cd l^–1; the detection limit is below 0.002 g l^–1 and can be lowered, if necessary, by enlargement of the original sample. According to the sensitivity of the method the typical blank of 0.022 g Cd l^–1 is high, but it is rather constant (mean variation from the mean: 0.0024 g l^–1).Teil XI: Fresenius Z. Anal. Chem. 299, 206–207 (1979)     

Determination of heavy metals in sea water and in marine organisms by flameless atomic absorption spectrophotometry

Summary An ultraquick light-beam oscillograph has been used to track the growing and destruction of the atomic cloud in a graphite tube atomizer. In view of the results obtained it was stated that the analytical signal is mainly determined by the stepwise growing of the atomic cloud and its simultaneous destruction by thermal expansion of the inert gas from the tube. Thermodiffusion and recondensation seem to be much slower processes. The dependence of the analytical signal on the settings of the atomizer or the presence of matrix components and on thermal ballast like the L'vov platform is discussed in view of the above thesis. Finally, some proposals are made to overcome the matrix effects by separating the atomization process from the heating and thermal expansion of the surrounding inert gas. For this purpose atomizers with two separate electric current circuits are recommended.

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Bestimmung von Schwermetallen im Meerwasser und in marinen Organismen durch flammenlose AtomabsorptionsspektralphotometrieXV. Matrixeffekte in Graphitrohr-Atomisatoren und Wege zu ihrer Überwindung

Zusammenfassung Ein schneller Lichtpunktschreiber wurde eingesetzt, um das Entstehen und den Abbau der Atomwolke in einem Graphitrohr-Atomisator zu verfolgen. Aufgrund der erhaltenen Ergebnisse wird geschlossen, daß das analytische Signal im wesentlichen durch das allmähliche Wachsen der Atomwolke und deren gleichzeitigen Abbau infolge thermischer Ausdehnung des Inertgases im Rohr bestimmt wird. Thermodiffusion und Rekondensation verlaufen offenbar langsamer. Die Abhängigkeit des analytischen Signals von den Geräteeinstellungen, von der Gegenwart bestimmter Matrixkomponenten und von thermischem Ballast wie der L'vov-Plattform wird im Lichte der o.a. These diskutiert. Schließlich werden einige Wege zur Behebung der Matrixabhängigkeit vorgeschlagen. Sie zielen auf eine möglichst weitgehende Trennung der eigentlichen Atomisierung vom Erhitzen und Sichausdehnen des umgebenen Inertgases. Hierzu werden Atomisatoren mit zwei getrennten elektrischen Heizkreisen vorgeschlagen.

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XIV. Mitt. Fresenius Z Anal Chem (1982) 310:254–256

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Presented at the Colloquium Spurenanalytik, Konstanz, 7.–9.4. 1981     

Determination of heavy metals in seawater and marine organisms by flameless atomic absorption spectrophotometry

Summary For the determination of cadmium in culture water from toxicological experiments with marine organisms direct flameless atomic absorption spectrophotometry seems to be an appropriate method, because it is less complicated than any combination with an extraction method. Unfortunately, it cannot be applied in the g·l^–1-range without modifications, because matrix effects lead to unacceptable variations in the results. It was found that these difficulties can be overcome by the addition of ammonium peroxodisulphate and sulphuric acid. A routine method basing on this effect has been developed.

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Bestimmung von Schwermetallen im Meerwasser und in marinen Organismen durch flammenlose Atomabsorptions-Spektralphotometrie. VI. Cadmiumbestimmung in Kulturwässern von toxikologischen Experimenten mit Meeresorganismen

Zusammenfassung Zur Cadmiumbestimmung in Kulturwasser von toxikologischen Versuchen mit marinen Organismen scheint die direkte flammenlose Atomabsorptions-Spektralphotometrie besonders geeignet zu sein, denn sie ist weniger umständlich als jede Kombination mit einer Extraktionsmethode. Ohne Modifikationen kann die Direktbestimmung jedoch im g/l-Bereich nicht eingesetzt werden, denn Matrixeffekte bewirken allzu starke Streuungen der Meßergebnisse. Es wird gezeigt, daß ein Zusatz von Ammoniumperoxodisulfat und Schwefelsäure zur Probenlösung eine deutliche Verbesserung bewirkt. Eine Routinemethode wurde entwickelt, bei der von diesem Effekt Gebrauch gemacht wird.

     

Determination of heavy metals in seawater and in marine organisms by flameless atomic absorption spectrophotometry

Summary The appicability of flameless AAS to direct cadmium determinations in seawater samples is limited to a level of about 2g l^–1 [22]. Thus, for lower concentrations, a combination with an extraction method has been tested. It has been shown that the extraction can well be carried out with ammonium pyrrolidine dithiocarbamate (APDC). However, several modifications of the well known APDC/MIBK-Method were necessary. The key for the method presented was the choice of an appropriate solvent (CCl₄, C₂Cl₄) for the reagent as well as for its Cd-complex. Then a simple, sensitive and miniaturized method has been developed, which has then been applied to a few natural seawater samples.

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Bestimmung von Schwermetallen im Meerwasser und in marinen Organismen durch flammenlose AtomabsorptionsspektralphotometrieVII. Ein einfaches Extraktionsverfahren zur Bestimmung extrem niedriger Cadmiumgehalte in kleinen Seewasserproben

Zusammenfassung Die direkte Bestimmung von Cadmium im Meerwasser durch flammenlose AAS stößt unterhalb einer Konzentration von 2g l^–1 auf beträchtliche Schwierigkeiten [22]. Deshalb wurde eine kombinierte Methode erprobt, bei welcher das Metall zunächst extrahiert und dann mittels flammenloser AAS bestimmt wird. Es zeigte sich, daß die Extraktion gut mit Ammoniumpyrrolidindithiocarbamat (APDC) ausgeführt werden kann. Es wurden jedoch erhebliche Abwandlungen der wohlbekannten APDC-MIBK-Extraktionsmethode erforderlich. Erst als es gelang, ein geeignetes Solvens (CCl₄, C₂Cl₄) sowohl für das APDC als auch für seinen Cd-Komplex zu finden, konnte eine einfache, empfindliche und miniaturisierte Bestimmungsmethode entwickelt werden, mit deren Hilfe dann der Cd-Gehalt einiger Meerwasserproben bestimmt wurde.

     

Determination of some heavy metals in sea water by atomic absorption spectrophotometry

Summary Direct determination of trace metals in sea water by flame atomic absorption technique suffers from serious interferences caused by the high salt content. Separation of the metals from the matrix has been effected by chelation and extraction with ammonium pyrrolidine dithiocarbamate and methyl-isobutyl-ketone. Besides a separation preconcentration and increased sensitivity is achieved with this extraction. Organic substances and metal-organic complexes are destroyed with UV-radiation before extraction is carried out. Flameless atomic absorption has been tried using the Heated Graphite Furnace combined with a) a selective volatilization procedure, b) removing of sodium from the samples using hydrated antimon pentoxide (HAP). Both methods were used to remove the interfering substances (mainly sodium salt). All the techniques have been compared by analysing the same sea water samples, some of which were also analysed by other laboratories.

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Bestimmung einiger Schwermetalle in Meereswasser durch Atomabsorptions-Spektralphotometrie

Zusammenfassung Die direkte Bestimmung der Spurenmetalle in Meereswasser durch Flammen-Atomabsorption wird durch den hohen Salzgehalt behindert. Die Abtrennung der Metalle von der Matrix wurde durch Komplexierung und Extraktion mit Ammoniumpyrrolidindithiocarbamat und Methylisobutylketon erreicht, wodurch außerdem eine Anreicherung und Steigerung der Empfindlichkeit erzielt wird. Organische Substanzen und metallorganische Komplexe können durch UV-Bestrahlung vor der Extraktion zerstört werden. Die flammenlose Technik mit Hilfe des erhitzten Graphitrohres wurde in Kombination mit a) einer selektiven Verdampfungsmethode und b) der Entfernung des Natriums mit hydratisiertem Antimonpentoxid eingesetzt. Alle Verfahren wurden an Hand der gleichen Wasserproben verglichen. Tests wurden auch von anderen Laboratorien durchgeführt.

This work was made possible by substantial grants from International Atomic Energy Agencies (IAEA) and from the Royal Norwegian Council for Scientific and Industrial Research.     

Determination of heavy metals in sea water and in marine organisms by graphite furnace AAS

Summary This paper is a plea for a reference material containing extremely low concentrations of Pb and Cd. A reasoning is given by a historical overview on the main topics of pollution research in relation to those metals. Emphasis has changed from toxicological tests (with high concentrations) over hot spots in the environment (certain organisms and organs, such as kidney and liver, showing significantly elevated concentrations) to mechanisms of transport and modelling. That development has been accompanied and promoted by methodological improvement. Those concentrations, which have to be determined with a sufficiently high precision are now in the lower background range. A proper standard material for such purpose could be fish muscle which, over and above, could be spiked, if necessary, for measurements in a higher concentration range.

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Bestimmung von Schwermetallen in Meerwasser und marinen Organismen mit Hilfe der Graphitofen-AASXXII. Fischmuskel an Stelle von Leber und Algen als Referenzmaterial für Blei- und Cadmiumbestimmungen

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Part XXI. Cadmium determination in coastal water samples from the German Bight (1985) Vom Wasser 64:53–68     

Determination of lithium in sea water by atomic absorption and by flame emission spectrophotometry

Summary Comparison of two instrumental methods for the analysis of lithium in sea water showed that both atomic absorption and flame emission spectrophotometry can be used without pretreatment of the sample. The interference of the other constituents of sea water in the analysis has been studied. Calibrations using an artificial sea water or the standard addition method may be used.

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Zusammenfassung Ein Vergleich der beiden Methoden hat gezeigt, daß zur Analyse von Lithium im Meerwasser sowohl die Atomabsorptionsspektrophotometrie, als auch die Flammenspektrophotometrie ohne Vorbehandlung der Probe angewendet werden können. Der Einfluß der anderen Bestandteile des Meerwassers auf die Analyse wurde untersucht. Für die Eichung des Verfahrens wurde künstliches Meerwasser sowie die Methode des Standardzusatzes verwendet.

     

Determination of chromium by atomic absorption spectrophotometry of chromium acetylacetonate : Determination of chromium in sea water

A sensitive atomic absorption method is described for the determination of chromium at sub-microgram levels. Chromium(III) is converted to its acetylacetone complex and extracted into MIBK. The atomic absorption sensitivity is thus en hanced two-fold compared to chromium (III) in aqueous medium. The detection limit of chromium is 0.015 p.p.m. with an acetylene-air flame; the sensitivity obtained with other chromium, methods under the same instrumental conditions is compared. The method can be applied to the determination of chromium in sea water; at a level of ca. 1.6 μg Cr/1, the precision is ±0.06 μg/1.     

Determination of wear metals in lubricating oils by flame atomic absorption spectrophotometry

A simple, rapid and reliable method was developed for the determination of copper, nickel, iron and lead in fresh and used lubricating oil samples by flame atomic absorption spectrophotometry (FAAS). In the present study, a mixture of organic solvents containing propionic acid and iso-butylmethyl ketone (1: 1) was used to extract the metals from lubricating oil samples followed by FAAS analysis. Aqueous standard solutions can be easily employed with the proposed mixed solvent system instead of organometallic standards. The analytical results obtained by employing the proposed solvent extraction system were found to be in good agreement with the results for aqueous media obtained after the destruction of oil samples matrix. Percentage recovery studies showed 88–98% for Cu, 92–95% for Fe, 96–106% for Ni and 84–100% for Pb with relative standard deviation of 2–6%. The developed method was effectively applied to routine determination of Cu, Ni, Fe, and Pb in lubricating oil samples.     

Determination of copper,nickel, and cadmium in sea water by apdc chelate coprecipitation and flameless atomic absorption spectrometry

Copper, nickel, and cadmium can be determined in 100 ml of sea water by coprecipitation with cobalt pyrrolidinedithiocarbamate and graphite atomizer atomic absorption spectrometry. Concentration ranges likely to be encountered and estimated (1 σ ) analytical precisions are 1–6 nmol kg^-1 (±0.1) for copper, 3–12 nmol kg^-1 (±0.3) for nickel and 0.0–1.1 nmol kg^-1 (±0.1) for cadmium. The technique may be applied to fresh-water samples with slight modification.     

Determination of trace metals in polymers by flameless atomic absorption with a solid sampling technique

A method for determining trace metals in polymers which combines flameless atomic absorption with a solid sampling technique is described. The method is applied to the analysis of iron, copper and chromium and is compared with results obtained from analysis of solutions of the polymers. Optimal conditions for achieving maximal accuracy and sensitivity are discussed. The effects of various matrix interferences and the heterogeneous distribution of trace metals in polymers are discussed.     

Determination of chromium in sea water by atomic absorption spectrometry

A method for the determination of chromium in sea water is described which requires minimal sample preparation. The chromium from filtered samples is oxidized with permanganate, extracted with ammonium pyrrolidine dithiocarbamate into MIBK, and analyzed by atomic absorption spectrometry in a fuel-rich air-acetylene flame. Non-filterable solids are extracted with 12 M hydrochloric acid and analyzed. Detection limits for the methods are 0.05 μg 1^-1 in the soluble phase and 0.06 μg 1^-1 in the particulate phase.     

Determination of thallium by atomic absorption spectrophotometry

Summary The determination of thallium by atomic-absorption Spectrophotometry is described. Many substances interfere with the direct analysis of thallium under the conditions chosen. However, these interferences can be overcome by adding a lithium, potassium, or sodium buffer (5000 ppm). In this way the deviations caused by foreign substances can be reduced to less than ten per cent. Under the same conditions the effect of organic solvents has been studied.

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Zusammenfassung Die Bestimmung von Thallium mit Hilfe der atomaren Absorptionsspektrophotometrie wird beschrieben. Die direkte Bestimmung von Thallium wird im allgemeinen durch viele Fremdionen in höheren Konzentrationen gestört. Durch Verwendung eines Li-, K-, oder Na-Puffers (5000 ppm) können die Störungen auf weniger als 10% herabgesetzt werden. Unter den gleichen experimentellen Bedingungen wird die Wirkung von organischen Lösungsmitteln untersucht.