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The capability of three analytical techniques, inductively coupled plasma-atomic emission spectrometry (ICP-AES), anodic stripping voltammetry (ASV), and instrumental neutron-activation analysis (INAA) have been compared for the determination of Cd, Fe, Pb, and Zn in airborne particulate matter, collected on cellulose filters, from the atmosphere of the large area of Thessaloniki, Greece. Two procedures were tested for quantitative leaching of these elements from the filters before ICP-AES and ASV, digestion with aqua regia in a Teflon autoclave, after dissolution of the organic matter with HClO4 under ambient conditions, and ultrasonic extraction with a mixture of HNO3 and HCl. Validation of the leaching and digestion procedures revealed that digestion in the autoclave is more effective, especially for Fe. The concentrations of these elements over a decade in both industrial and urban areas of the investigated region are compared.
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PMID:Comparison of inductively coupled plasma-atomic emission spectrometry, anodic stripping voltammetry and instrumental neutron-activation analysis for the determination of heavy metals in airborne particulate matter. 1137 Oct 61

A method for the determination of zinc octoate (zinc 2-ethylhexanoate) and acypetacs zinc in occupational hygiene samples and wood treatments formulations is described. The zinc carboxylates are liquid-liquid partitioned between toluene and 1 M HCl, with the liberated acids being extracted into the toluene and zinc (chloride) into the acid. The carboxylic acids are then methylated using trimethylsilyldiazomethane-methanol and the resultant methyl esters are selectively and sensitively analysed by gas chromatography with mass selective detection (GC-MS). Alternatively, the zinc content of the acid extract can be analysed by inductively coupled plasma atomic emission spectroscopy (ICP-AES). GC-MS is the preferred method of analysis for zinc octoate, where a single analyte (methyl-2-ethylhexanoate) is produced for analysis. Because acypetacs zinc contains a complex mixture of carboxylates, quantitative GC-MS analysis of the methyl esters produced is impractical and ICP-AES is the preferred method for quantitation. In this case, GC-MS can be used to confirm the identity of the product used. The analysis of occupational hygiene samples (cotton pads, gloves and socks as well as Tenax tubes and GF/A filters) spiked with metal carboxylates is demonstrated. Recoveries around 70-90% and reproducibilities of 5-23% (n=6-8) were typically achieved for the determination of tin octoate (a surrogate for zinc octoate) at spiking levels ranging from 4 to 190 microg per sampling device. Recoveries around 102-106% and reproducibilities of 10-12% (n=5-6) were typically achieved for acypetacs zinc at spiking levels ranging from 100 mg per sampling device. Reaction yields for the octoate methylation reaction were in the region of 85-87%. The method was used to monitor for occupational exposure to zinc octoate and acypetacs zinc during the application of wood treatments to fences.
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PMID:Determination of organo-zinc based fungicides in timber treatments employing gas chromatographic analysis with mass selective detection and/or inductively coupled plasma atomic emission spectroscopy. 1158 39

The reaction of [Mo(3)S(4)(H(2)O)(9)](4+) with Bi(III) in the presence of BH(4)(-) (rapid), or with Bi metal shot (3-4 days), gives a heterometallic cluster product. The latter has been characterized as the corner-shared double cube [Mo(6)BiS(8)(H(2)O)(18)](8+) by the following procedures. Analyses by ICP-AES confirm the Mo:Bi:S ratio as 6:1:8. Elution from a cation-exchange column by 4 M Hpts (Hpts = p-toluenesulfonic acid), but not 2 M Hpts (or 4 M HClO(4)), is consistent with a high charge. The latter is confirmed as 8+ from the 3:1 stoichiometries observed for the oxidations with [Co(dipic)(2)](-) or [Fe(H(2)O)(6)](3+) yielding [Mo(3)S(4)(H(2)O)(9)](4+) and Bi(III) as products. Heterometallic clusters [Mo(6)MS(8)(H(2)O)(18)](8+) are now known for M = Hg, In, Tl, Sn, Pb, Sb, and Bi and are a feature of the P-block main group metals. The color of [Mo(6)BiS(8)(H(2)O)(18)](8+) in 2.0 M Hpts (turquoise) is different from that in 2.0 M HCl (green-blue). Kinetic studies (25 degrees C) for uptake of a single chloride k(f) = 0.80 M(-)(1) s(-)(1), I = 2.0 M (Hpts), and the high affinity for Cl(-) (K > 40 M(-)(1)) exceeds that observed for complexing at Mo. A specific heterometal interaction of the Cl(-) not observed in the case of other double cubes is indicated. The Cl(-) can be removed by cation-exchange chromatography with retention of the double-cube structure. Kinetic studies with [Co(dipic)(2)](-) and hexaaqua-Fe(III) as oxidants form part of a survey of redox properties of this and other clusters. The Cl(-) adduct is more readily oxidized by [Co(dipic)(2)](-) (factor of approximately 10) and is also more air sensitive.
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PMID:Preparation and Properties of the Corner-Shared Double Cube [Mo(6)BiS(8)(H(2)O)(18)](8+) as a Derivative of [Mo(3)S(4)(H(2)O)(9)](4+) in Aqueous Acidic Solutions. 1166 43

The chalcogenide-rich trinuclear Mo(IV)(3) clusters [Mo(3)Y(7)(H(2)O)(6)](4+), containing single &mgr;(3)-(Y(2)(-)) and three &mgr;-(Y(2)(2)(-)) core ligands, have been obtained for the first time from polymeric {Mo(3)Y(7)Br(4)}(x)() via [Mo(3)Y(7)Br(6)](2)(-) (Y = S, Se). ICP analyses of 2 M HCl solutions give Mo:S and Mo:Se ratios consistent with the formulas indicated, and on reaction with concentrated HBr, 85% recovery of (Et(4)N)(2)[Mo(3)S(7)Br(6)], the structure of which is known, has been achieved. Abstraction of S and Se with PPh(3) (two-phase system), or the water-soluble phosphine (3-SO(3)C(6)H(4))(3)P(3)(-) (PR(3)(3)(-)), gives quantitative formation of [Mo(3)S(4)(H(2)O)(9)](4+) and [Mo(3)Se(4)(H(2)O)(9)](4+). With CN(-), both abstraction of S (or Se) and CN(-) replacement of H(2)O is observed, giving [Mo(3)S(4)(CN)(9)](5)(-) and [Mo(3)Se(4)(CN)(9)](5)(-) as products. It was possible to assign which atom of the sideways eta(2),eta(2) &mgr;-(S(2)(2)(-)) and &mgr;-(Se(2)(2)(-)) ligands is abstracted using the structurally characterized [Mo(3)S(4)Se(3)(H(2)O)(6)](4+) cluster. Thus it was demonstrated that with the phosphines the equatorial (to the Mo(3) plane) Se atoms of the three &mgr;-(SSe(2)(-)) groups are removed with formation of the Mo(3)S(4)(4+) core. Kinetic studies on the reactions of [Mo(3)S(7)(H(2)O)(6)](4+) and [Mo(3)Se(7)(H(2)O)(6)](4+) with PR(3)(3)(-) give approximately 10(3) faster abstraction rate constants (k(a)/M(-)(1) s(-)(1)) for S than Se. The rate law k(a) = k(1)[H(+)] + k(-)(1)[H(+)](-)(1) is explained by the involvement of protonated &mgr;-(Y(2)(2)(-)) (k(1)) and an H(2)O conjugate-base form (k(-)(1)). Equilibration rate constants for X(-) = Cl(-) and Br(-) substitution of H(2)O on [Mo(3)S(7)(H(2)O)(6)](4+) and [Mo(3)Se(7)(H(2)O)(6)](4+) are however independent of [H(+)] in the range 0.5-2.0 M investigated. With X(-) concentrations up to 1.3 M (S cluster) and 0.3 M (Se), the uniphasic reactions are assigned as substitution of the H(2)O cis to &mgr;(3)-(Y(2)(-)) at each Mo. At 25 degrees C formation rate constants 10(4)k(f)/M(-)(1) s(-)(1) are as follows for [Mo(3)S(7)(H(2)O)(6)](4+): Cl(-) (1.83); Br(-) (2.07). The same rate constants are as follows for [Mo(3)Se(7)(H(2)O)(6)](4+): Cl(-) (6.7); Br(-) (33). Formation rate constants for Cl(-) are surprisingly 2 x 10(6) times slower than for the reaction of [Mo(3)S(4)(H(2)O)(9)](4+) with Cl(-). Reactions of Mo(3)S(7)(4+) with three metals (Sn, Ni, In) were studied briefly.
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PMID:Preparation and Solution Properties of Chalcogenide-Rich Clusters [Mo(3)Y(7)(H(2)O)(6)](4+) (Y = S, Se): Kinetics of PR(3)(3-) Abstraction of Y from &mgr;-(Y(2)(2-)) and H(2)O Substitution by Cl(-) and Br(-). 1166 47

For selective dissolution of Mn oxides as components of soil (easily reducible oxides) 0.05 mol L(-1) and 0.1 mol L(-1) NH2OH.HCl acidified to pH 2 and for dissolution of Fe oxides (crystalline form of the oxides) 0.25 mol L(-1) NH2OH.HCl in 25% acetic acid, 0.2 mol L(-1) oxalate buffer and 0.1 mol L(-1) ascorbic acid in oxalate buffer were tested. Dissolved elements were determined by ICP-MS and ICP-OES. The studies indicate that the use of 0.05 mol L(-1) NH2OH.HCl in nitric acid solution (pH 2) and 0.1 mol L(-1) ascorbic acid in 0.2 mol L(-1) oxalate buffer led to selective leaching of trace metals bound by Mn and Fe oxide phases in soil. Comparison of different extraction schemes indicates that the trace elements investigated are mainly bound to minerals consisting of crystalline Fe oxides and insoluble minerals (under the extraction conditions used). The studies also indicate that Mn oxides and organic matter retain a major mobile fraction of the elements investigated in the soil.
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PMID:Selective leaching of elements associated with Mn-Fe oxides in forest soil, and comparison of two sequential extraction methods. 1168 55

Concentrations, distributions and mobility of chemical elements were investigated in reduced sulfur-rich estuarine sediments located in western Finland. The main objective was to determine the possible extent of metal leaching when dredged masses of these sulfur-rich sediments are dumped on the land and thus exposed to air. When dredged, the reduced sulfur in the sediments oxidises resulting in a lowering of pH, which in turn is expected to leach metals. The study area is an artificial lake claimed from the Botnian sea in 1962. In this lake, several mass-kills of fish have occurred, believed partly to be due to dredging. Two sediment samples (0-50 and 50-100 cm) were taken from 39 sampling points in the lake. These samples were leached in aqua regia (2:2:2 HNO3/HCl/H2O1) and analysed for Fe, Al, Mg, Ca, K, P, Na, Mn, Zn, Ba, V, Sr, Cr, Ni, Cu, Co, As, Pb, B, Mo and Cd with ICP-AES. Sulfur and organic carbon were analysed with Leco. In a controlled laboratory experiment, the sediments were allowed to oxidise for 1 year while moisturised with deionised water every month. The pH and conductivity were determined in the beginning of the experiment (reduced state) and in the end (oxidised state). In the supernatants in the oxidised states the amount of leached metals (Na, Al, Mn, Zn, Sr, Co, Ni, Cu, Cd, Cr, Pb, U, Li, Rb and As) were determined with ICP-MS. The sediments were found to contain low levels of toxic metals but, as expected, high concentrations of sulfur. In the experiment, pH was lowered (down to 3.0) and the conductivity increased in all samples due to oxidation and release of metal ions. The extent of leaching varied between 0.03% for As and 12.3% for Na. Critical pH values, at which high amounts of metals begin to leach, were obtained graphically. These values varied between 4.8 (Ni) and 3.3 (Cr). Not all elements were controlled by pH, e.g. Mn correlated well with its aqua regia leachable concentration. In a planned dredging operation in the area some 23,300 t (10,500 m3) (dry wt.) of sediments will be dredged. The amounts of metals likely to be leached, according to the results from this study, are as follows (kg): Al (1710), Mn (1230), Zn (59), Sr (39), Co (13), Ni (12), Cu (2) and less than 1 kg of Cd-Cr-As-Pb.
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PMID:Concentrations and leachability of chemical elements in estuarine sulfur-rich sediments, W. Finland. 1184 56

Soluble species of phosphorus, sulfur, selenium and eight metals (Mn, Fe, Co, Ni, Cu, Zn, Mo and Cd) in soybean flour and common white bean seeds were investigated by size exclusion chromatography (SEC) and inductively coupled plasma mass spectrometry (ICP-MS). Samples were extracted by 0.02 mol l(-1) Tris-HCI buffer solution (pH 7.5). Fractionation of sample extracts by preparative scale SEC was accomplished using a Fractogel EMD BioSEC column (600 x 16 mm) and 0.02 mol l(-1) Tris-HCl buffer solution (pH 7.5) as mobile phase (flow rate: 2 ml min(-1)). A 2-ml sample was injected. Contents of elements in chromatographic fractions were determined by AAS, ICP-AES and ICP-MS. The elution profiles of P, Fe, Co, Ni, Cu, Zn and Mo in both samples were similar. Main species of Co, Ni, Cu, Zn and Mo were found in the low molecular weight region (2-5 kDa), whereas Fe is predominantly bound to high molecular weight compounds (180 kDa). The dominant phosphorus fraction was detected in the medium molecular weight region (10-30 kDa) and the other fraction in the low molecular weight region. Isotachophoretic analysis of chromatographic fractions revealed that the main phosphorus compound in the medium molecular weight region is phytic acid. SEC on Superdex 75 and Superdex Peptide columns (300 x 10 mm) was performed in on-line hyphenation with ICP-MS. The same mobile phase was used with a flow rate of 0.5 ml min(-1); volume of injected sample was 200 microl. Element specific chromatograms were obtained by continuous nebulization of effluent into ICP-mass spectrometer measuring intensities of 47(PO)+ and 48(SO)+ oxide ions and 55Mn, 57Fe, 59Co, 62Ni, 65Cu, 66Zn, 82Se, 95Mo and 114Cd nuclides. Chromatographic profiles of elements are generally analogous to those obtained with a Fractogel column, but better chromatographic resolution of separated species was achieved so that slight differences between samples were revealed. Estimated molecular weights of major phosphorus species in soybean flour and common white bean seed extracts are 6 and 3.6 kDa, respectively, whereas those of minor phosphorus species in both samples are 0.7 kDa. Traces of phosphorus were also detected in the high molecular weight region (130 kDa). Chromatograms of P, Ni, Cu, Zn and Mo compounds in both extracts are similar but not identical. Molecular weights of major Cu and Zn species are approximately 1 and 0.4 kDa for soybean flour and white bean seeds, respectively. In cases of Mn, Fe, Co and Se, the element profiles of soybean flour and white bean seed extracts are significantly different.
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PMID:Fractionation of phosphorus and trace elements species in soybean flour and common white bean seeds by size exclusion chromatography-inductively coupled plasma mass spectrometry. 1201 35

The objective of the work carried out was to recommend protocols for the collection, filtration (0.45 microm) and preservation of surface water samples for the subsequent determination of total 'dissolved' Hg. Cold vapour (CV) ICP-MS was employed to determine Hg; samples were acidified to a strength of 4 mol l(-1) HCl and 1% NaBH4 was used as the reducing agent in-line. Four types of 125 ml bottles were studied (Teflon, fluorinated ethene propene copolymer, FEP; high density polyethylene, HDPE; polyethylene terephthalate copolyester, PET; polypropylene, PP), together with three cleaning methods (EPA Methods 1631, 1638 and a rinse with reverse osmosis deionised water, 'MilliQ'). The transmission properties of the four materials were also studied to evaluate the potential for contamination from atmospheric Hg0. Results of this bottle study (n = 195), all below the detection limit of 0.5 ng l(-1), indicate that the bottles of choice, from an economic and time-saving perspective, are HDPE and PP, the latter being preferable if the sample is to be stored in a contaminated atmosphere. The bottles would be used on a once-only basis, negating the need for labourious and costly cleaning on repeat use. A simple rinse with MilliQ water would suffice prior to use. Twelve 0.45 microm filter systems (mostly Millipore and Gelman) were studied for (a) their potential Hg contamination properties and (b) their retention of Hg, possibly in colloidal form, during filtration. Ottawa River water, spiked at 50 ng l(-1) Hg, was used as a control sample. Again blank values were all negative, indicating contamination was not a concern but different recoveries of Hg were obtained across the different systems. The optimum systems to use, in that they provided maximum recovery (ca 80%) of Hg, are the Millipore Sterivex capsule and the Millipore Millex disc, both based on the hydrophilic Durapore membrane. The lowest recoveries (23-36%) were found with the Gelman AquaPrep systems and the Millipore HN nylon filter. Four control samples, Ottawa, Rideau and Gatineau Rivers, and a MilliQ blank, were used to study three preservation approaches, in the media: 0.5% BrCl, 2% HCl and 0.04% K2Cr2O7 in 1% HNO3. Mercury was stable for 28 days in a medium of 0.5% BrCl in all four samples but the other two media showed a loss of up to ca 20% Hg over this time frame, the loss being sample and time dependent. This may be a species transformation which is not detected by CV-ICP-MS from an HCl medium but this requires further investigation. Mercury was stable over the 28 days in the spiked blank MilliQ sample for all three preservation media.
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PMID:Sample collection, filtration and preservation protocols for the determination of 'total dissolved' mercury in waters. 1208 Oct 47

Selenium concentrations and its spatial distribution in soils, spermatophytes and bryophytes (mosses) around the Cockle Creek Zn-Pb smelter, New South Wales were studied from May to November 2000. Selenium was determined by ICP-MS on soils digested in nitric and hydrochloric acid (HNO3:HCl = 3:1), and plant samples digested in distilled concentrated nitric acid. At distances greater than 3 km, selenium in soils, spermatophytes and bryophytes converge to uniform values, which are considered to represent the background value. Mean selenium in soils around the smelter is two times higher than the background value. Mean concentration of selenium in plants around the smelter is three times greater than that for background plants. Selenium from 'in site' bryophyte is twice that found in the background bryophyte. The transfer coefficients of selenium between plants and soils are low, especially at a distance less than 1 km from the smelter. However, mosses show the reverse trend. This study indicates that the Zn-Pb smelter is one of the anthropogenic point sources of selenium pollution in the Lake Macquarie district.
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PMID:Selenium in soils, spermatophytes and bryophytes around a Zn-Pb smelter, New South Wales, Australia. 1210 67

An electrothermal atomic absorption (ETAAS) method for the determination of traces of iron (0.1-1.0 microgram g-1) in Fe-doped indium phosphide (InP) has been developed. In order to overcome the indium matrix-effect and to achieve a useful detection limit, a preliminary solvent-extraction of Fe(III) with acetylacetone (HAA) is necessary. After sample dissolution with hydrochloric acid (1 + 1) the digest is evaporated to dryness, Fe(II) is oxidized to Fe(III) with nitric acid, the residue is dissolved in 0.01 mol L-1 HCl and the iron is extracted at pH 2.0 with 0.5 mol L-1 HAA in toluene. The organic phase is injected into the graphite furnace and the iron is directly evaluated by external organic standard calibration. The limit of detection (3SB) resulting from further in-situ preconcentration is 0.03 microgram g-1. When the method was applied to the analysis of real samples containing 0.2-0.7 microgram g-1 Fe, the RSD was in the range 8-21%. Results were compared with those independently obtained on the decomposed sample solution with inductively coupled atomic emission spectrometry (ICP-AES). The detection limit of the ICP-AES method, that needs matrix-matched standards, is 0.20 microgram g-1.
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PMID:Determination of traces of iron in indium phosphide by electrothermal atomic absorption spectrometry combined with solvent extraction. 1212 54


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