Ashley T. Townsend

The determination of copper, zinc, cadmium and lead in urine by high resolution ICP-MS

High resolution ICP-MS was used to determine Cu, Zn, Cd and Pb in urine. The effect of sample dilution, preparation method and choice of internal standard were assessed. Sample dilution (1+9) with In as the internal standard was found to offer an acceptable compromise between analytical accuracy and sample throughput. A spectral resolution of 3000 was used to separate Cu and Zn isotopes from interferences commonly found in biological matrices, while a resolution of 300, offering increased sensitivity and lower detection limits, was used for Cd and Pb. The accuracy and precision of the analytical method were evaluated using two Bio-Rad Lyphochek standard urines. The concentrations of Cu, Zn, Cd and Pb in Bio-Rad Level 1 reference urine were determined by external calibration and were found to agree to within 0-17% of recommended values (Cu 48, Zn 710, Cd 6.5 and Pb 14.3 ng g –1 ). Closer agreement of 0-7% was found for Bio-Rad Level 2 reference urine (Cu 63, Zn 1057, Cd 12.3 and Pb 69 ng g –1 ). Forty-two urine samples from seven workers occupationally exposed to Cd were analysed and the results were compared with those obtained from 11 samples collected from four non-exposed volunteers. Similar average concentrations of Cu and Zn were found in both groups when the results were normalised to creatinine levels. Workers exposed to Cd were found to have an average urine Cd concentration elevated approximately 7-8-fold over that measured for the control group (about 2.2 compared with about 0.3 ng g –1 , or 1.7 and 0.2 μg per gram of creatinine when normalised). Urinary levels of Pb were slightly increased in the cadmium exposed workers (about 6 compared with about 4 ng g –1 ).

The determination of copper, zinc, cadmium and lead in urine by High Resolution Inductively Coupled Plasma Mass Spectrometry

High resolution ICP-MS was used to determine Cu, Zn, Cd and Pb in urine. The effect of sample dilution, preparation method and choice of internal standard were assessed. Sample dilution (1+9) with In as the internal standard was found to offer an acceptable compromise between analytical accuracy and sample throughput. A spectral resolution of 3000 was used to separate Cu and Zn isotopes from interferences commonly found in biological matrices, while a resolution of 300, offering increased sensitivity and lower detection limits, was used for Cd and Pb. The accuracy and precision of the analytical method were evaluated using two Bio-Rad Lyphochek standard urines. The concentrations of Cu, Zn, Cd and Pb in Bio-Rad Level 1 reference urine were determined by external calibration and were found to agree to within 0-17% of recommended values (Cu 48, Zn 710, Cd 6.5 and Pb 14.3 ng g -1). Closer agreement of 0-7% was found for Bio-Rad Level 2 reference urine (Cu 63, Zn 1057, Cd 12.3 and Pb 69 ng g -1). Forty-two urine samples from seven workers occupationally exposed to Cd were analysed and the results were compared with those obtained from 11 samples collected from four non-exposed volunteers. Similar average concentrations of Cu and Zn were found in both groups when the results were normalised to creatinine levels. Workers exposed to Cd were found to have an average urine Cd concentration elevated approximately 7-8-fold over that measured for the control group (about 2.2 compared with about 0.3 ng g -1, or 1.7 and 0.2 mg per gram of creatinine when normalised). Urinary levels of Pb were slightly increased in the cadmium exposed workers (about 6 compared with about 4 ng g -1).

Microbial life at −13 °C in the brine of an ice-sealed Antarctic lake

The permanent ice cover of Lake Vida (Antarctica) encapsulates an extreme cryogenic brine ecosystem (−13 °C; salinity, 200). This aphotic ecosystem is anoxic and consists of a slightly acidic (pH 6.2) sodium chloride-dominated brine. Expeditions in 2005 and 2010 were conducted to investigate the biogeochemistry of Lake Vida’s brine system. A phylogenetically diverse and metabolically active Bacteria dominated microbial assemblage was observed in the brine. These bacteria live under very high levels of reduced metals, ammonia, molecular hydrogen (H2), and dissolved organic carbon, as well as high concentrations of oxidized species of nitrogen (i.e., supersaturated nitrous oxide and ∼1 mmol⋅L−1 nitrate) and sulfur (as sulfate). The existence of this system, with active biota, and a suite of reduced as well as oxidized compounds, is unusual given the millennial scale of its isolation from external sources of energy. The geochemistry of the brine suggests that abiotic brine-rock reactions may occur in this system and that the rich sources of dissolved electron acceptors prevent sulfate reduction and methanogenesis from being energetically favorable. The discovery of this ecosystem and the in situ biotic and abiotic processes occurring at low temperature provides a tractable system to study habitability of isolated terrestrial cryoenvironments (e.g., permafrost cryopegs and subglacial ecosystems), and is a potential analog for habitats on other icy worlds where water-rock reactions may cooccur with saline deposits and subsurface oceans.

Precise lead isotope ratios in Australian galena samples by high resolution inductively coupled plasma mass spectrometry

High resolution inductively coupled plasma mass spectrometry (HR-ICP-MS) was used to measure Pb isotope ratios in standard solutions and Pb mineral digests. The RSD values obtained for208Pb/204Pb, 207Pb/204Pb, 206Pb/204Pb, 208Pb/206Pb and 207Pb/206Pb were 0.13, 0.11, 0.11, 0.046 and 0.048%, respectively (values as 1σ). These values were obtained from 30 analyses of three different standard sample types (multi-element standard, NIST SRM 981 and a Broken Hill galena digest). Based on 39 analyses of 11 galena samples from different locations around Australia, the difference between HR-ICP-MS and conventional TIMS values for 208Pb/204Pb, 207Pb/204Pb, 206Pb/204Pb, 208Pb/206Pb and 207Pb/206Pb ratios was generally better than±0.2%. This paper outlines a very simple and rapid analytical method for the measurement of Pb isotope ratios, and is one of the first studies to use HR-ICP-MS to measure Pb isotope ratios in galena and galena-bearing ores.

A comparison of an optimised sequential extraction procedure and dilute acid leaching of elements in anoxic sediments, including the effects of oxidation on sediment metal partitioning.

The effect of oxidation of anoxic sediment upon the extraction of 13 elements (Cd, Sn, Sb, Pb, Al, Cr, Mn, Fe, Co, Ni, Cu, Zn, As) using the optimised Community Bureau of Reference of the European Commission (BCR) sequential extraction procedure and a dilute acid partial extraction procedure (4h, 1 molL(-1) HCl) was investigated. Elements commonly associated with the sulfidic phase, Cd, Cu, Pb, Zn and Fe exhibited the most significant changes under the BCR sequential extraction procedure. Cd, Cu, Zn, and to a lesser extent Pb, were redistributed into the weak acid extractable fraction upon oxidation of the anoxic sediment and Fe was redistributed into the reducible fraction as expected, but an increase was also observed in the residual Fe. For the HCl partial extraction, sediments with moderate acid volatile sulfide (AVS) levels (1-100 micromolg(-1)) showed no significant difference in element partitioning following oxidation, whilst sediments containing high AVS levels (>100 micromolg(-1)) were significantly different with elevated concentrations of Cu and Sn noted in the partial extract following oxidation of the sediment. Comparison of the labile metals released using the BCR sequential extraction procedure (SigmaSteps 1-3) to labile metals extracted using the dilute HCl partial extraction showed that no method was consistently more aggressive than the other, with the HCl partial extraction extracting more Sn and Sb from the anoxic sediment than the BCR procedure, whilst the BCR procedure extracted more Cr, Co, Cu and As than the HCl extraction.

Modern sampling and analytical methods for the determination of trace elements in marine particulate material using magnetic sector inductively coupled plasma-mass spectrometry

Trace elements often limit phytoplankton growth in the ocean, and the quantification of particulate forms is essential to fully understand their biogeochemical cycling. There is presently a lack of reliable measurements on the trace elemental content of marine particles, in part due to the inadequacies of the sampling and analytical methods employed. Here we report on the development of a series of state-of-the-art trace metal clean methods to collect and process oceanic particulate material in open-ocean and sea ice environments, including sampling, size-fractionated filtration, particle digestions and analysis by magnetic sector inductively coupled plasma-mass spectrometry (ICP-MS). Particular attention was paid to the analysis of certified reference materials (CRMs) and field blanks, which are typically the limiting factor for the accurate analysis of low concentrations of trace metals in marine particulate samples. Theoretical detection limits (3 s of the blank) were low for all 17 elements considered, and varied according to filter material and porosity (sub-microg L(-1) for polycarbonate filters and 1-2 microg L(-1) for quartz and polyester filters). Analytical accuracy was verified using fresh water CRMs, with excellent recoveries noted (93-103%). Digestion efficiencies for various acid combinations were assessed using sediment and plankton CRMs. Using nitric acid only, good recoveries (79-90%) were achieved for Mo, Cd, Ba, Pb, Mn, Fe, Co, Ni, Cu, Zn and Ga. The addition of HF was necessary for the quantitative recovery of the more refractory trace elements such as U, Al, V and Cr. Bioactive elements such as P can also be analysed and used as a biomass normaliser. Our developed sampling and analytical methods proved reliable when applied during two major field programs in both the open Southern Ocean and Antarctic sea ice environments during the International Polar Year in 2007. Trace elemental data are presented for particulate samples collected in both suspended and sinking marine material, and also within sea ice cores.

Measurement of Trace Elements in Marine Environmental Samples using Solution ICPMS. Current and Future Applications

The strengths and weaknesses of using inductively coupled plasma mass spectrometer (ICPMS) measurements of samples in solution for marine environmental analyses using real world examples is discussed. ICPMS can detect nanogram per litre concentrations of trace elements but suffers from polyatomic interferences generated from the sample matrix. Most of the routine trace elements measured in marine biological tissue and sediment digests, with the notable exceptions of iron, chromium, vanadium, and selenium, are not subject to severe interferences. Low recoveries of trace elements from sediments are due to the inability of extraction acids to remove trace elements such as chromium and nickel from sediment matrices. The use of ICPMS offers the advantage that elements such as phosphorus, which previously required elaborate digestion procedures and a colorimetric determination, can be rapidly determined using nitric acid digestion alone. The use of flow injection coupled with ICPMS allows on-line preconcentration of trace metals and metalloids using chelation by ion-exchange resins or hydride generation and trapping as well as separation from matrix elements. Thus, the routine determination of trace elements and inorganic and methylated arsenic, antimony, mercury, and germanium species in open-ocean waters is possible. The coupling of HPLC and GC to ICPMS allows the measurement of metal and metalloid species in biological and sediment extracts. However, extraction of unaltered species from matrices presents a challenge. Many of the species found in the environmental samples are not known and analytical standards are not available. The concurrent use of HPLC-MS is needed to confirm these species.

The use of Pb isotope ratios determined by magnetic sector ICP-MS for tracing Pb pollution in marine sediments near Casey Station, East Antarctica

Magnetic sector inductively coupled plasma mass spectrometry (ICP-SMS) was used to measure lead concentrations and isotope ratios in marine sediments and other samples collected from near the Australian Antarctic Station Casey. Precisions obtained from the repetitive analysis of a standard Broken Hill Pb sample at a concentration of ∼40 ng g−1 in solution were <±0.2% for ratios involving 204Pb, and <±0.1% for those referenced to 206Pb or 207Pb (n = 12 replicates over 2 days, values as 1s). Ratios were accurate to within ∼±0.1% for the analysis of this standard sample. Comparative measurements between ICP-SMS and TIMS had typical differences in values of 10 ng g−1, instrumental capability was characterised by isotopic precisions ranging from 0.1-0.5% (1s) for ratios involving 204Pb, and <0.25% (1s) for ratios with 206Pb or 207Pb as the basis (typically found from triplicate analyses). For sediments of low Pb concentration (<10 ng g−1 in the sample digest), isotope ratios to 204Pb were found to be limited by instrument counting statistics when using standard ICP-SMS. To help overcome this problem, Pb isotope ratios for these samples were measured with a capacitive decoupling Pt guard electrode employed, offering considerable signal enhancement (5–10×). These natural background sediments were found to display typical Pb isotope ratios of 40.5, 15.5, 18.6 and 1.19 for 208Pb/204Pb, 207Pb/204Pb, 206Pb/204Pb and 206Pb/207Pb. For comparison, the most contaminated samples had Pb isotope ratios of approximately 36.2, 15.4, 16.4 and 1.06 for 208Pb/204Pb, 207Pb/204Pb, 206Pb/204Pb and 206Pb/207Pb, respectively. Evidence of simple two component mixing between anthropogenic and natural geogenic Pb was found near Casey Station. Runoff from the Thala Valley tip site, adjacent to the bay, was identified as a clear source of Pb pollution, with impacted sediments displaying an isotopic signature approaching that of abandoned lead batteries collected from the tip. These batteries possessed Pb isotope ratios identical to Australian Broken Hill lead. In this study, the use of Pb isotope data has proved to be a sensitive method of assessing contamination levels in the Antarctic marine environment adjacent to a waste disposal site. Lead isotope ratios have proved superior to simple elemental concentration determinations when distinguishing between impacted and non-impacted samples. ICP-SMS has been shown to offer relatively fast, accurate and cost effective Pb isotope ratios, with precisions suitable for many environmental applications.

Historical lead isotope record of a sediment core from the Derwent River (Tasmania, Australia): A multiple source environment

A 105 cm sediment core from the Derwent River (Tasmania, Australia) was collected in 2004 and was characterised considering both physical (loss on ignition at 550 °C and grain size) and chemical (Fe, Cu, Zn, Cd and Pb concentrations, Pb isotope ratios and (210)Pb dating) properties. The core was analysed to (i) investigate the historical profiles of some important elements associated with the Risdon zinc refinery adjacent to the Derwent River, (ii) determine Pb isotopic signatures of sediment samples, and (iii) assess the veracity of Pb isotope ratios as indicators of contaminant Pb input. Extractable metal concentrations were (all values as mgkg(-1), non-normalised for grain size) Fe: 20,000-35,000, Zn: 42-4500, Pb: 5-1090, Cu: 13-141, and Cd: 1-31; with a close correlation between Cu, Zn, Cd and Pb. Metal enrichment factors (normalised to Al) were Pb: 0.9-144, Zn: 0.8-93, Cd: 0.8-30, Cu: 0.8-8.9 and Fe: 0.9-1.3, confirming anthropogenic contributions of Cu, Zn, Pb and Cd to the sediments. The onset of metal contamination above background levels occurred at a depth between 43 and 49 cm, with maximum concentrations noted near 20 cm for Cu, Zn, Cd and Pb. Lead isotope ratios were determined in sediments using sector field ICP-MS, and were found to be 36.5-38.8, 16.5-18.7 and 1.07-1.20 for (208)Pb/(204)Pb, (206)Pb/(204)Pb and (206)Pb/(207)Pb ratios, respectively. Major Australian ores processed at the refinery over the previous ~90 years include those from Broken Hill, Rosebery, Mt Isa, Elura, Hellyer and Century deposits. Anthropogenic impact by Pb with Broken Hill type isotopic ratio was initially evident in the core at 43-49 cm. The introduction of Rosebery and Elura ores to the refinery was also clearly noted. Pb isotope ratios further highlight that the Derwent River has been exposed to a greater impact by anthropogenic Pb in comparison to other major Tasmanian rivers, namely the Huon and Tamar.

Determination of vanadium as 4-(2-pyridylazo)resorcinol–hydrogen peroxide ternary complexes by ion-interaction reversed-phase liquid chromatography

The separation and determination of the vanadium(V) ternary complex formed with 4-(2-pyridylazo)resorcinol (PAR) and hydrogen peroxide using ion-interaction reversed-phase high-performance liquid chromatography on a C18 column has been investigated. The optimal mobile phase was a methanol-water solution (32:68, v/v) containing 3 mM tetrabutylammonium bromide, 5 mM acetic acid and 5 mM citrate buffer at pH 7, with absorbance detection at 540 nm. The stoichiometry of the ternary complex of vanadium at pH 6 in 10 mM acetate buffer using the mole ratio and Jobs method by HPLC indicated that the mole ratio of V(V):PAR:H2O2 was 1:1:1. The optimal conditions for precolumn formation of the ternary complex were 10 mM acetate, 7 mM H2O2, 0.3 mM PAR, and pH 6. The method gave relative standard deviations of retention time, peak area and peak height for the ternary complex of 0.187, 0.45 and 0.57%, respectively. The detection limit (at a signal-to-noise ratio of 3) for V(V) was 0.09 ng/ml in the digested sample using a 100-microl injection loop (or 0.09 microg/g in the solid fertiliser sample). The method was applied to the analysis of fertilisers (phosphate rocks and nitrogen, phosphorus and potassium fertiliser). The results for vanadium obtained by the HPLC method agreed well with those from magnetic sector inductively coupled plasma MS analysis.