The determination of selenium in sea water,silicates and marine organisms

Spectrophotometric procedures are described for the determination of selenium in sea water, silicates (especially marine sediments) and marine organisms. Coprecipitation with iron(III) hydroxide at pH 4–6 is used to concentrate selenium and to separate it from many of the commoner elements. Separation from iron and other cations is achieved by ion exchange. Selenium is determined photometrically with diaminobenzidine. Isotope dilution with selenium-75 is used to correct results for the small losses occurring during the analysis. Silicates can be decomposed without loss of selenium by means of a mixture of hydrofluoric and nitric acids. The method of Cummins et al., with sulphuric and perchloric acids in presence of molybdate ion, is highly satisfactory for the decomposition of bio-materials. For sea water, which contains ca. 0.4–0.5 <mg Se/l, a standard deviation of 0.03 μg/l was obtained. A silicate sediment and a sea weed containing ca. 1.5 μg Se/g and 0.8 μg Se/g respectively gave coefficients of variation of 8.0% and 4.7%. The U.S. Geological Survey standard granite G1 was found to contain 2.5 ± 0.1 μg Se/g.     

Radiochemical determination of plutonium in marine samples by extraction chromatography

Very low levels of plutonium (^239,240Pu and ²³⁸Pu) in marine samples (sea water,sediments, marine organisms) are determined by extraction on columns of tri-n-octyl phosphine oxide supported on microporous polyethylene (Micro thene-710), electrode- position, and α-spectrometry. ²³⁶Pu or ²⁴²Pu is added as the yield detector and a high-resolution α-spectrometer is used for counting. The final recoveries are 62.6% ± 9.7(σ)for sea water, 45.4% ± 9.6(0) for sediments and 81.7%± 4.5(σ) for marine organisms. Themethod enables ^239.240pu and ²³⁸Pu to be detected at the femtocurie level.     

Flame photometric determination of potassium in sea water and marine organisms

A convenient flame photometric procedure for determining potassium in sea water and biological materials is described. Factors affecting the intensity of the spectral line emitted by potassium ions were studied. The major constituents of sea water showed no spectral interference on the potassium analysis. Chloride ions and sulphuric acid gave a negative radiation interference while sodium ions showed a positive effect. The “internal standard addition” procedure was used for eliminating the effect of these interfering constituents.An average potassium/chlorinity ratio of 0.538 was obtained for the Pacific coastal water with potassium concentration being expressed in mg-atom. The applicability of this procedure for the détermination of potassium in biological materials was also demonstrated.     

The determination of chlorinated aliphatic hydrocarbons in air, natural waters, marine organisms, and sediments

A gas Chromatographic procedure is described for the determination of chlorinated aliphatic hydrocarbons in the atmosphere, natural waters, aquatic organisms and sediments. Air samples are passed through activated carbon traps and the chloro compounds are later desorbed by heating in a current of nitrogen. Chloro compounds are stripped from water samples by bubbling with nitrogen and from bio-materials and sediments by heating in a current of nitrogen. In each instance, the chlorinated compounds are trapped in copper columns packed with Chromosorb coated with silicone oil, and cooled to -78°. The chloro compounds are subsequently swept off these columns into a gas chromatographic column with a current of argon. Detection of the Chromatographic peaks is performed with an electron-capture detector. The procedure gives near quantitative recoveries of a range of chlorinated hydrocarbons from natural samples.     

Determination of arsenic in sea water,marine plants and silicate and carbonate sediments

Cocrystallization with thionalide in a 0.05 N sulphuric acid medium is proposed for the recovery of microgram amounts of arsenic from sea water and from solutions prepared by the decomposition of silicates and marino plants. After destruction of the organic precipitant, arsenic is determined photomotrically by means of a single-solution molybdenum blue method. The overall recovery for the whole process is 97-98%. Arsenic was determined in sea water with a coefficient of variation of 1.3% at a level of 2 μg As/l. Coefficients of variation of 2.6% and 1.7% were found, for the determination of the element in marine sediments and plants at levels of 6.6 μg/g and 1.7 μg/g respectively. The U. S. Geological survey standard granite G 1 was found to contain 1.2 μg As/g     

Radiochemical procedure for the determination of plutonium isotopes in powdered milk

Summary A radiochemical procedure for the determination of alpha-emitting isotopes of plutonium in powdered milk is proposed. The procedure involves sample dissolution (by HNO₃ and HClO₄), separation by ionic-exchange resin, electrodeposition and alpha-spectroscopy. In order to determine the chemical recovery, ²⁴²Pu was employed as a tracer. A reference material (Marine Sediment IAEA 135) was analyzed to validate such procedure, and to show its reliability. Afterwards, some powdered milk, produced for international trade, was analyzed and chemical recovery was found to be around 95%.     

Modes of137Cs desorption from marine sediments by sea water

Sea water is observed to be a good desorbing agent for¹³⁷Cs from marine sediments. Investigations on the sites of¹³⁷Cs binding and their abundance by desorption over extended periods indicated that, whatever the time of contact of sorption,¹³⁷Cs has three modes of desorption: fast component with desorption half-time of 30–50 min, medium component with desorption half-time of 25–50 h and slow component with desorption half-time of 31–112 days. These are expected to be sites of ion exchange, slower exchange and trapped Cs in the clay mineral layer lattices.     

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     

Presence of uranium and plutonium in marine sediments from gulf of tehuantepec, mexico

Uranium and plutonium were determined in the Tehua II-21 sediment core collected from the Gulf of Tehuantepec, Mexico. The analyses were performed using radiochemical separation and alpha spectroscopy. Activity concentrations of alpha emitters in the sediment samples were from 2.56 to 43.1 Bq/kg for ²³⁸U, from 3.15 to 43.1 Bq/kg for ²³⁴U and from 0.69 to 2.95 Bq/Kg for ^239+240Pu. Uranium activity concentration in marine sediment studied is generally high compared with those found in sediments from other marine coastal areas in the world. The presence of relatively high concentrations of anthropogenic plutonium in the sediments from the Gulf of Tehuantepec suggests that anthropogenic radionuclides have been incorporated and dispersed into the global marine environment.     

Irradiation of cellulose nitrate film with plutonium isolated from sea organisms

A practical application was described for the use of cellulose nitrate film /CLN/ as a dielectric detector for recording -particle activity of plutonium in sea organisms. Purified plutonium from fish-flesh, clam and oyster was electroplated onto stainless steel disc. Sample disc was exposed to CLN film for sufficient period of time to produce -tracks. The tracks were eteched in NaOH solution and counted under light microscope.     

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 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 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 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)     

A new method of plutonium speciation in sea water

A new method of plutonium speciation in large volume of sea water was developed by using adsorption of Pu(IV)-Xylenol Orange chelate and Pu-Arsenazo chelate on XAD-2 resin, respectively. The tetravalent plutonium ion reacts selectively with Xylenol Orange in acid solution and that adsorbed on XAD-2 resin. Total plutonium can be collected onto the resin in the form of its Arsenazo-III complex. The determination of plutonium then was carried out by alpha-ray spectrometric method after decomposition of organic complexes and ion exchange separation. The present method is confirmed for convenient and rapid preconcentration procedure for plutonium shipboard chemistry.     

Radiochemical determination of210Po and210Pb in water

A method for²¹⁰Po and²¹⁰Pb determination in water samples is described. The nuclides are concentrated, in presence of added²⁰⁸Po and lead carrier, by evaporation. Then the polonium is plated electroless from the acidic solution on a copper planchet and measured by alpha spectrometry.²¹⁰Pb separation from the other isotopes is based on the solutility of PbSO₄ in citrate.²¹⁰Pb content is determined by measuring the activity of its daughter²¹⁰Bi. The critical steps in the isolation of lead have been examined and discussed.     

Determination of inorganic and methylated arsenic species in marine organisms and sediments

The determination of inorganic arsenic, monomethylarsenic and dimethylarsenic in marine organisms and estuarine sediments is described. The arsenic species are isolated by solvent extraction, separated by ion-exchange chromatography and selectively determined by aisine generation. Recoveries of spikes of 5 and 10 μg of arsenic taken through the whole procedure were 92–96%. Typical results obtained in a study of the forms of arsenic in several species of macroalgae, tissues of Mercenaria mercenaria and estuarine sediments are given.