The determination of antimony in natural waters with particular reference to sea water

A procedure is described for the determination of antimony in natural waters at concentrations down to 0.1 μg/l or less. The element is concentrated by coprecipitation with hydrous manganese dioxide (produced by the reaction of permanganate with ethanol). It is separated from manganese, iron and interfering elements by extraction from 5 M sulphuric acid, 0.01 M with respect to iodide, using methyl isobutyl ketone. After back-extraction with 0.4 M hydrochloric acid, it is determined photometrically using rhodamine B. The overall chemical yield of the process is measured radiochemically and amounts to ca. 80%. Sea water samples from the Irish Sea were found to contain 0.13–0.40 μg Sb/l.     

Determination of tungsten in silicates and natural waters

Coprecipitation with hydrous manganese dioxide is used for the concentration of tungsten from natural waters (including sea water) and from solutions prepared from silicate rocks and sediments by hydrofluoric acid attack. After dissolution of the hydrous manganese dioxide precipitate in acidified sulphur dioxide solution, cation excliange is used to separate tungsten and molybdenum from other coprecipitated elements, hydrogen peroxide being used as eluant. Molybdenum is separated from tungsten by extraction of its dithiol complex from 24 N hydrochloric acid medium containing citric acid and can be determined photometrically. After destruction of citric acid, tungsten is determined photometrically with dithiol. The overall cliemical yield of th analytical process is 94±1%. The standard deviation of the method is ±0.010 μg for sea water (0.116 μg W/l) and ca 0.05 μg/g for siliceous sediments containing 0.5–1.0 μg W/g.     

The automatic determination of silicate-silicon in natural waters with special reference to sea water

An automatic method using a Technicon AutoAnalyzer is described for the determination of silicate in natural waters in the range 0–4 mg Si/l. It is based on the conversion of silicate to β-silicomolybdic acid which is reduced by means of a metolsulphite reagent to molybdenum blue. Interference of phosphate is prevented by oxalic acid. The relationship between silicate concentration and optical density is linear in both fresh waters and sea water. With sea water the salt error of the method is ca. 5% at a salinity of 35‰ A coefficient of variation of 0.8% was found at a silicate concentration of 1 mg Si/l with both fresh and sea waters.     

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.     

Anwendung von ionenaustauschverfahren zur bestimmung von spurenelementen in natürlichen wässern—V: Blei

A method is described which makes possible the separation of lead from natural waters at the ppM level, and its final determination by spectrophotometry or atomic absorption. The sample is made 0.15M in hydrobromic acid, filtered, and passed through Dowex 1 X8 (bromide form). The lead is sorbed on the resin and most of the other elements present are separated from it. The lead is eluted with 6M hydrochloric acid and determined by the dithizone method or by atomic-absorption. The method was used to determine lead in drinking water and water from the Danube, lead concentrations in the range 2–14 ppM being found.     

Preconcentration and determination of trace amounts of lead (II) as thenoyltrifluoroacetone complex with dibenzo-18-crown-6 by synergistic extraction and atomic absorption spectrometry

A new method for the preconcentration and determination of trace amounts of lead at the μg/L level in natural waters has been established based on the formation of the thenoyltrifluoroacetone (TTA) complex with dibenzo-18-crown-6 (DB18C6) by means of synergistic extraction and back-extraction combined with atomic absorption spectrometry (AAS). The effect of various factors (synergism with TTA and DB18C6, shaking time, preconcentration factor, composition of the extracted species, and foreign ions etc.) on the extraction and back-extraction of lead has been investigated in detail. The lead-TTA chelate in o-dichlorobenzene forms a stable adduct with DB18C6 as Pb(TTA)₂ DB18C6. The stability constant (β) of the adduct determined by curve fitting method was log β = 4.2. The amount of lead in natural waters such as tap water (Kanazawa University) and Kakehashi river (Komatsu City) determined by the present method was found to be 0.64 ± 0.02 μg/L and 5.10 ± 0.03 μg/L, respectively.     

Direct determination of arsenic in fresh and saline waters by electrothermal vaporization inductively coupled plasma mass spectrometry

A method is described for the direct determination of arsenic in fresh and saline waters by electrothermal vaporization inductively coupled plasma mass spectrometry. Arsenic could be determined directly in waters containing up to 10 000 μg ml⁻¹ NaCl without interference from the formation of ⁷⁵ArCl⁺. For non-saline waters, arsenic was determined directly with the addition to both aqueous calibration standards and samples of 0.1 μg each of Pd and Mg to act as physical carriers. For the analysis of highly saline waters, the use of Pd and Mg chemical modifier served to thermally stabilize arsenic up to a temperature of 1000°C, while the separate addition of 8 mg of ammonium nitrate was used to remove chloride from the sample. This eliminated serious spectral interference on ⁷⁵As⁺ from ⁷⁵ArCl⁺. Although the ArCl⁺ spectral interference was completely eliminated, residual Na co-volatilized with As caused signal suppression, requiring the use of the method of standard additions for calibration. An absolute limit of detection limit for As of 0.069 pg was obtained corresponding to 6.9 pg ml⁻¹ in a 10 μl sample.     

Dosage de l'acidite libre dans les solutions aqueuses concentrees de plutonium(IV)

A method for the determination of free acidity in concentrated aqueous solutions of plutonium (IV) is described. The plutonium-EDTA complex is formed by addition of the calcium-EDTA complex and the neutralization titration with sodium hydroxide is followed potentiometrically, the equivalence point being determined by a graphical method. The relative standard deviation is 1%. Uranium and iron in small amounts do not interfere. The method is applicable to solutions which are ca, 1 N in acid and which contain up to 200 g Pu/l.     

Determination of nanomolar levels of formate in natural waters based on a luminescence enzymatic assay

A light-producing reaction utilizing three enzymes, bacterial luciferase, dehydrogenase and diaphorase, can be used to determine formic acid in natural waters at nanomolar concentrations. The method is rapid and convenient, requiring no preconcentration, desalting or derivatization procedures. Determinations can be done on small sample volumes (25 μl) at room temperature and pH 7. The precision (relative standard deviation for sea water samples containing 1.0 μM formate was 9.0% (n = 15). The reaction is specific for formate with a detection limit of 20 nM (signal-to-noise ratio = 3). Results for applications of the method to sea, estuarine and rain water are given.     

The spectrophotometric determination of antimony in water,effluents, marine plants and silicates

A spectrophotometric procedure is described for the determination of antimony in natural waters (including sea water and effluents), algae and silicates. After a preliminary oxidative digestion for waters, or acid attack for algae and silicates, the element is quantitatively coprecipitated at pH 5.0 with hydrous zirconium oxide. The precipitate is dissolved in acid, and, after reduction with titanium(III) chloride, antimony is oxidized to antimony(V) with sodium nitrite. The ion pair of the SbCl₆^- ion with crystal violet is extracted with benzene and its absorbance is measured at 610 nm (molar absorptivity 74,000 l mol^-1 cm^-1). Extraction with toluene causes some loss of sensitivity. The detection limit is 0.005 μg l^-1; relative standard deviations are 0.5% and 1.1% for spiked distilled water (0.5 μg l^-1) and sea water (0.26 μg l^-1), respectively. A wide range of anions and cations cause no interference at levels many times those in natural waters. The technique can be adapted for application to marine algae and silicates; relative standard deviations are 1.8% and 2% for samples of Pelvetia canaliculata (0.19 μg Sb g^-1) and a Pacific Ocean red clay (1.08 μg Sb g^-1), respectively. Results for the U.S. Geological Survey Standard rocks GSP1 (2.7 ppm) and DTS1 (0.53 ppm) are in good agreement with those of earlier workers.     

Differential pulse cathodic stripping voltammetric speciation of trace level inorganic arsenic compounds in natural water samples

A simple, fast and sensitive speciation method is described for inorganic arsenic in water at the μg/l level, applicable in the laboratory and in the field, based on differential pulse cathodic stripping voltammetry (DPCSV). Only As(III) is deposited on a Hg electrode in the presence of Cu and Se in HCl medium. Determination of total As is performed by reducing As(V) to As(III) using sodium meta-bisulfite/sodium thiosulfate reagent stabilized with ascorbic acid. As(V) is quantified by difference. The detection limit (S/N>3) was 0.5 μg/l with a linear range from 4.5 to 180 μg/l. The relative standard deviation (n=6) was 2.4, 2.5, 4.2% for As(III) and 8.0, 6.8, 9.0% for As(V) at levels of 45, 10, and 5 μg/l, respectively. Analysis of the NIST 1640 natural water standard yielded total arsenic concentration 26.5±3.4 μg/l (n=3) compared to the certified value of 26.7 μg/l. Results obtained on several natural water samples analyzed both in the laboratory and on-site compared well with those obtained by HR ICP-MS, GFAAS and IC-AFS. Ions (phosphate, iron, manganese) commonly found in groundwater containing arsenic were found to have negligible interference.     

Adsorption of zinc on polymeric chelating adsorbents in the analysis of natural water

The physicochemical and analytical properties of polymeric chelating adsorbents, polystyrene-2-hydroxy-(1-azo-1′)-2′-hydroxybenzene derivatives, to zinc ions were studied. A possible chemical mechanism of the complexation process was based by a number of parameters. A procedure was proposed for the preconcentration of zinc followed by its stripping voltammetric determination in natural water. The detection limit of the proposed procedure (0.1 μg/L) ensures reliable ecological control of natural waters; the relative standard deviation was 1–4% at a concentration level of n × 10^?5%.     

Extraction—photometric determination of trace amounts of nitrite in waters

Traces of nitrite in river water can be determined by extraction spectrophotometry. Nitrite in 100 ml of sample water at pH 1.5–3.0 diazotizes p-aminoacetophenone, which is then coupled with m-phenylenediamine at the same pH. The 2,4-diamino-4'-acetyl-azobenzene formed is extracted into 5 or 10 ml of toluene at pH 9 and the absorbance is measured at 450 nm. The molar absorptivity is about 2.3·lO⁴ l mol^?1 cm^?1. The ions normally present in river water do not interfere. The nitrite contents in river waters in Okayama Prefecture, Japan, are 1–30 P.P.b.     

Determination of seven trace elements in natural waters after separation by solvent extraction and anion-exchange chromatography

A method is described for the determination of cadmium, cobalt, copper, manganese, lead, uranium, and zinc in samples of natural waters. After acidification with hydrochloric acid the water sample is filtered and the diethyldithiocarbamates of the trace elements are isolated by extraction with acetone—chloroform (2:5) at pH 5. Following this preconcentration step the metal ions are adsorbed on a column of the strongly basic anion-exchange resin Dowex 1-X8 (chloride form) using as sorption solution a mixture (5:4:1, $\text{v}\text{v}$) of tetrahydrofuran, methyl glycol and 6 M hydrochloric acid. Successive elution is effected with 6 M hydrochloric acid (Co, Cu, Mn and Pb), 1 M hydrochloric acid (U) and 2 M nitric acid (Cd and Zn); the metal ions in the eluates are determined by atomic absorption spectrophotometry (except uranium, which is determined fluorimetrically). The procedure was used to determine the trace-metals in water and snow samples collected in Austria and to analyse a sample of sea water from the Adriatic Sea.     

Determination of trace quantities of tin by neutron activation analysis

A neutron activation method of general applicability has been developed for determining traces of tin in a variety of samples. The samples and comparative standards, sealed into ampoules, are irradiated intermittently for 3 days at a neutron flux of ca, 3 · 10¹¹ n/cm²/sec, followed by carrier radiochemical separations mainly consisting of solvent extraction steps. As little as 0.1 μg Sn can be easily determined by comparing the induced β-activity of ¹²¹Sn (27.5 h) with that of a standard, The method is rapid and has a reasonably high chemical yield of about 50%. Results are quoted for the tin contents of a number of materials including silicate rocks, sea waters, biological materials and steels.     

Application de la chromatographie en phase gazeuse et de la spectrométrie de masse à la recherche des résidus de pendiméthaline dans les eaux

(Application of gas chromatography and mass spectrometry in analysis for pendimethaline residues in waters.)The extraction of the herbicide pendimethaline [N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine from waters with benzene is described. The method is suitable for the determination of this herbicide at residue level, by capillary gas chromatography and its identification by mass spectrometry. The detection limit is 1 μl^?1 for a 1 l sample of water.     

The automatic determination of fluoride in sea water and other natural waters

A Technicon AutoAnalyzer has been used for the determination of 0–1.5 μg fluoride/ml in sea water and other natural waters. Photometric measurement is made on the blue complex formed by reaction with the chelate formed between lanthanum and alizarin fluorine blue, The method has a coefficient of variation of ca. 0.9% at a fluoride level of 1.5 μm/ml.     

The determination of vanadium in sea and natural waters,biological materials and silicate sediments and rocks

Vanadium was concentrated from sea and natural waters by coprecipitation with iron (III) hydroxide, and separated from iron and other elements by ion exchange, using hydrogen peroxide as a very selective eluting agent. The element was determined photometrically with diaminobenzidine. The ion-exchange process was also used to separate vanadium from other elements in the analysis of silicate rocks and marine plants. Coefficients of variation of 2.8%, 1.3% and 2.5% were found for the determination of the element in sea water, marine sediments and marine plants at levels of 1.8 μg/l, 57 μg/g and 2.2 μg/g, respectively. The U.S. Geological Survey standard granite GI was found to contain 17.2±0.9μg V/g.     

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     

Evaluation of Extraction Procedures of Organochlorine Pesticides from Natural Waters and Sediments

Abstract

This study aims to evaluate different procedures for the extraction of organochlorine pesticides (OCP's) from natural waters and sediments. In the case of extraction from water, a C18 disk solid-phase extraction method was employed. Recovery experiments in the range of 40 to 200 ng/l with selected organochlorine compounds resulted in average recoveries between 80 and 100%. Four different solvents, hexane, ethyl acetate, acetonitrile and methanol, were tested as eluting agents. Best recoveries were obtained with ethyl acetate and hexane. A comparative study of OCP sediment extraction procedures was performed employing sonication, Soxhlet extraction and shake-flask methods. The capacity of these methods to recover OCP's from a sediment sample fortified at 50 ng/g was evaluated using hexane : acetone (1:1 v/v), hexane: acetone (8:2 v/v), acetonitrile and dichlorometane. The three extraction techniques gave similar results and dichloromethane was the most effective solvent. The optimised methods were applied in the analysis of waters and sediments from the “Aiguamolls de l'Empordà” Nature Park, Girona (Spain).