Determination of Rare Earth Elements and Y in Ultramafic Rocks by ICP-MS After Preconcentration Using Fe(OH)3 and Mg(OH)2 Coprecipitation

A simple and reliable method to separate rare earth elements (REE) from Mg, Fe, K, Na, Ca and Ba in ultramafic rocks has been developed, thereby concentrating their abundances. The sample (0.3 g) was digested with HF and HNO₃ in a PTFE bomb, placed in a stainless steel container and, after drying, the insoluble residue was dissolved in 6 ml of 10% v/v HNO₃. Following the addition of 50% triethanolamine and 30% m/v NaOH solution, the REE were precipitated along with Mg(OH)₂, such that the majority of Fe, K and Na in the solution could be separated by centrifuging. The precipitate was dissolved in 1 ml HNO₃ and a buffer solution of NH₄Cl/NH₄OH at pH = 9.0 was added to precipitate the REE along with any remaining Fe as Fe(OH)₃, and so achieve separation from Mg, Ca and Ba, which remained in the solution. In this way, REE could be separated from major elements and were concentrated by a factor of about 60. The recovery of REE was more than 95% using this method. Four ultramafic rock reference materials, PCC-1 (USGS), JP-1 (GSJ), DZE-1, DZE-2 (IGGE) and one new proficiency testing sample GeoPT12 (GAS Serpentinite) were analysed by ICP-MS using indium as an internal standard. The quantitation limits were about 0.02–0.2 ng g⁻¹. Smooth chondrite-normalised REE patterns were obtained with a precision for REE determination of about 2–9%.     

Additional Provisional Elemental Values for LKSD-1, LKSD-2, LKSD-3, LKSD-4, STSD-1, STSD-2, STSD-3 and STSD-4

Provisional values related to element concentration derived from partial extractions as well as some additional total concentration data are reported for eight CCRMP sediment reference materials. These values are intended to supplement previously published data for these samples. The partial extractions for which data are reported include dilute HNO₃ - dilute HCl, concentrated HNO₃ -concentrated HCl and concentrated HNO₃ -concentrated HClO₄.     

Use of Chelating Resin YPA4 Micro-Columns for the On-Line Preconcentration and Separation of Gold(III), Silver(I), Palladium(II) and Platinum(IV) in Geological and Environmental Samples and Their Determination by Inductively Coupled Plasma-Atomic Emission Spectrometry

A simple and selective method of flow injection (FI) using a micro-column packed with chelating resin YPA₄ as solid phase extractant was developed for the preconcentration and separation of trace amount of noble metals, Au(III), Ag(I), Pd(II) and Pt(IV), followed by ICP-AES determination. In HNO₃ media, the chelating resin was selective towards Au(III), Ag(I), Pd(II) and Pt(IV), and the analysed ions were readily desorbed quantitatively with 5 ml of 2.5% m/v thiourea. Effects of acidity, sample flow rate and concentration, elution solution and interfering ions on the recovery of the analytes were systematically investigated. Under optimum conditions, the adsorption capacities of YPA₄ for Au(III), Ag(I), Pd(II) and Pt(IV) were 67.2, 43.1, 64.8 and 27.6 mg per gram of resin in HNO₃ media, respectively. It was found that YPA₄ could be used for more than eight runs in HNO₃ media without loss of capacity. The proposed method was used for the determination of trace noble metals in geological and environmental samples, and the analytical results obtained were in good agreement with the recommended values.     

Determination of Platinum and Palladium in Geological Samples by Inductively Coupled Plasma-Atomic Emission Spectrometry after Preconcentration with Immobilised Nanometric Titanium Dioxide

A new method has been developed for the determination of platinum and palladium based on separation and preconcentration with a microcolumn packed with nanometric TiO₂ immobilised on silica gel (immobilised nanometric TiO₂) prior to their determination by inductively coupled plasma-atomic emission spectrometry. The optimum experimental parameters for the preconcentration of Pt and Pd, such as the pH of the sample solution, its flow rate and volume, the type and concentration of eluent and interfering ions, have been investigated. Platinum and Pd could be quantitatively retained by immobilised nanometric TiO₂ in the pH range 6–8, then eluted completely with 2.0 ml of 3% m/v thiourea in 1.0 mol l⁻¹ HNO₃. The detection limits of this method for Pt and Pd were 12 and 7. 6 ng l⁻¹ with an enrichment factor of 100, and the relative standard deviations were 4.7% and 3.3% at the 10 ng ml⁻¹ level. The method has been applied for the determination of Pt and Pd in geological samples with satisfactory results.     

Concentrations of Trace Elements in Carbonate Reference Materials Coral JCp-1 and Giant Clam JCt-1 by Inductively Coupled Plasma-Mass Spectrometry

Trace elements in the Geological Survey of Japan carbonate reference materials Coral JCp-1 and Giant Clam JCt-1 were determined by inductively coupled plasma-mass spectrometry after digestion with 2% v/v HNO₃. A standard addition method was adopted in this determination in order to neutralise the Ca matrix effect. In addition, Sc, Y, In and Bi were used as internal standards to control the matrix effect and correct instrumental drift. Of the eighteen elements measured in JCp-1, precisions for fourteen elements, including Cu, Cd and Ba, were better than 10% RSD and concentrations ranged from 0.002 μg g^-1 (Cs) to 8.02 μg g^-1 (Ba). The concentrations of measured trace elements in JCt-1, except for Cu, were lower than those in JCp-1. Precisions for all elements with concentrations higher than 0.04 μg g^-1 in JCt-1 were also better than 10% RSD and concentrations were found to be between 0.001 μg g^-1 (Cs) and 4.84 μg g^-1 (Ba). The concentrations of more than fifteen trace elements in the aragonite reference materials are reported here for the first time. Both reference materials are suitable for use in geochemical studies of environmental reconstruction based upon biogenic carbonate materials.     

Determination of Trace Elements in the Quartz Reference Material UNS-SpS and in Natural Quartz Samples by ICP-MS

A procedure for the digestion and analysis of quartz samples was developed to measure trace element concentrations in natural quartz. The certified glass sand reference material UNS-SpS was chosen to assess the precision, accuracy and detection limit of the analytical method. Quartz was digested with HF/HNO₃ in a closed glassy carbon vessel and analysed by means of quadrupole ICP-MS with external calibration. Analyte concentrations of the sand UNS-SpS were compared with certified and other values from the literature. The abundances of a number of elements (Pr, Gd, Ho and Er) in the reference material are reported here for the first time. The procedure was then applied to three quartz samples from different geological settings to show that trace element data by ICP-MS can distinguish the origin of the sample.     

Determination of Rare-Earth Elements, Scandium, Yttrium And Hafnium in 32 Geochemical Reference Materials Using Inductively Coupled Plasma-Atomic Emission Spectrometry

The determination of twelve rare-earth elements (REE), scandium, yttrium and hafnium in 32 geochemical reference materials by inductively coupled plasma atomic emission spectrometry (ICP-AES) is reported. Results obtained show good agreement with previously published values and compilations. The method is based on a lithium metaborate fusion of the sample followed by a cation exchange separation. A small amount of oxalic acid added to the 6N HNO₃ eluant ensures the complete elution of hafnium with the other 14 elements.     

Major Element Data (1966–1978) for The Six "Nimroc" Reference Samples

The results are given for all the determinations made by the co-operating laboratories of major elements in the six NIMROC rock samples (granite, syenite, lujavrite, norite, pyroxenite and dunite) prepared by the National Institute for Metallurgy in 1966. Relevant statistical data are given for the sets of results for each major constituent, and recommended values for all constituents except Al₂0₃, Na₂0, K₂0and CO₂ in dunite, Fe₂O₃, MgO and CO₂ in the granite, Fe₂₃ and CO₂ in the norite and CO₂ in the pyroxenite.
This report and that on the trace and minor elements issued in 1978 complete the revision of the recommended values. It is suggested that analysts should concentrate rather on those constituents for which the results have shown such a wide scatter that they can be of no usc for reference purposes, than on those for which the ualues are fairly well established.     

High Pressure Asher Digestion and an Isotope Dilution-ICP-MS Method for the Determination of Platinum-Group Element Concentrations in Chromitite Reference Materials CHR-Bkg, GAN Pt-1 and HHH

New concentration data for Ru, Rh, Pd, Re, Os, Ir and Pt are presented for three chromitite reference materials. A simple and very effective procedure was applied for the measurements. Samples were spiked with enriched isotopes and digested in a HNO₃/HCl (5+2) acid mixture at 300 °C and 125 bar (1.25 × 10⁷ Pa) pressure in a high pressure asher (HPA-S, Anton Paar). The programme settings were changed as a function of mass (0.5, 1, 2 and 4 g) and time (5 and 15 hours). Complete chromitite dissolutions for three digestions at each setting were monitored using XRD analyses of the amorphous residue after digestion. The osmium concentration was determined by sparging the OsO₄ that was formed during digestion into a quadrupole ICP-MS. After drying and re-dissolution of the remaining residue, the other PGEs were separated on-line from their matrix in a simple cation-exchange column that was coupled to the ICP-MS. The concentrations were determined through isotope dilution and external calibration (Rh). By using the on-line separation, we were able to control interference effects (isobaric and molecular), which resulted in highly reproducible data. Replicate measurements of the reference material CHR-Bkg (SARM CRPG-CNRS) with sample masses ranging from 0.5 to 4 g showed very small standard deviations compared to the results from the initial collaborative trials and published data (e.g., 3.2% RSD vs. 32% RSD for Ru). Results for platinum showed the largest scatter, which is currently attributed to the small size of the test portion. In addition to CHR-Bkg, the first results for two chromitite reference materials "platinumore" GAN Pt-1 and "chromiumore" HHH issued by the Central Geological Laboratory of Mongolia are presented.     

DETERMINATION OF PHOSPHOROUS IN FIFTY-NINE GEOCHEMICAL REFERENCE SAMPLES BY EXTRACTIVE SPECTROPHOTOMETRY

A digestion procedure with sequential use of HF-HCl and HNO₃-HClO₄ involving yellow vanadium molybdophosphate complex and its extraction into isobutylmethylketone (IBMK) has been employed for estimation of phosphorus in 59 geochemical reference samples. The agreement between the results obtained from IBMK-extraction and the recommended values has been found to be better than those available from the usual procedures (i.e., estimation in the aqueous phase).     

Chemical Analysis of Iron Meteorites by Inductively Coupled Plasma-Mass Spectrometry

Iron meteorites were analysed for nineteen siderophile and chalcophile elements by conventional inductively coupled plasma-mass spectrometry with the specific aim of demonstrating that this technique is an effective alternative to the more routine, yet complex, methodologies adopted in this field such as instrumental or radiochemical neutron activation analysis. Two aliquots of each meteorite sample, in the form of small shavings, were dissolved, one in 6 mol l^-1 HNO₃ and the other in aqua regia , and diluted to a final concentration of 1 mg sample per 1 ml of solution, without pre-concentrating the analytes. Nitric acid solutions were used for the determination of the elements Cr, Co, Ni, Cu, Ga, Ge and As; aqua regia solutions were analysed for the elements Mo, Ru, Rh, Pd, In, Sn, Sb, W, Re, Ir, Pt and Au. Samples were analysed by external calibration, carried out using synthetic multi-elemental solutions, and internal standardisation (with Be, Rb and Bi selected as internal standards). The results obtained from the analyses of nine geochemically well-characterized iron meteorites (Canyon Diablo, Odessa, Toluca, Coahuila, Sikhote-Alin, Buenaventura, Tambo Quemado, Gibeon, NWA 859) with widely variable chemical compositions are in good agreement with literature values for most elements. Detection limits were generally below the lowest concentration observed in iron meteorites. The most notable exception is for Ge, which cannot be successfully determined in the low-Ge meteorites of groups IVA, IVB and IIIF and a number of ungrouped irons. A test of the overall reproducibility of the adopted method, undertaken by repeatedly analysing the same Odessa IAB meteorite specimen, yielded relative standard deviations (1 s ) of between 1 and 6% for all elements except Cr (40%).     

Determination of Carbonate Carbon in 41 International Geochemical Reference Samples by Coulometric Method

The carbonate-carbon (CO₂) content of forty-one geochemical reference samples has been determined by coulometric method following acid treatment of the sample for releasing CO₂. The method is superior to the conventional methods in speed, accuracy, sensitivity, specificity, and the coverage of CO₂ range. The results on NBS limestone samples agree well with the certified values. The precision of the method is 0.5 % r.s.d., and the practical detection limit is 10 ppm C.     

Pressurised Extraction Using Dilute Ammonia: A Simple Method for Determination of Iodine in Soil, Sediment and Biological Samples by Inductively Coupled Plasma-Mass Spectrometry

A simple sample treatment method for the accurate and precise determination of iodine in soil, sediment and biological samples by inductively coupled plasma-mass spectrometry (ICP-MS) is described. Iodine in samples was extracted in screw top PTFE-lined stainless steel bombs using a 10% v/v ammonia solution at 185 C for 18 hours (overnight), after which the extract was introduced into the ICP-MS for direct measurement. ¹²⁶Te was employed as the internal standard to compensate for matrix effects and instrument drift. The limit of detection (LOD, three times the standard deviation of the procedural blank solution, expressed as the concentration in the sample solution) was 0.003 ng ml-^-1. The limit of quantitation (LOQ, ten times the standard deviation of the procedural blank solution, expressed as the concentration in the solid samples, dilution factor DF = 100) was 0.01 μg g-^-1 (dry mass). The accuracy and precision of the method were demonstrated by analysing different Chinese geological certified reference materials (soils, stream sediments and a hair sample). The measured concentrations were in a good agreement with the certified values indicating that bias in the method was not significant. The precision (n = 10) for different concentrations ranged from 1.82% to 4.32% RSD. Comparison of the ammonia extraction procedure with a "sintering" method indicated that there was no significant difference in results obtained with the two methods for geological soil and stream sediment samples. However, for biological samples, such as hair, kelp, tea etc., the results obtained by the sintering method were far below those of the ammonia extraction method. The ammonia extraction has advantages, as it is simpler than the "sintering" method, and has a lower procedural blank, better detection limits and reproducibility. Due to the simplicity of the method, a high rate of sample throughput is possible.     

Determination of Lithium Contents in Silicates by Isotope Dilution ICP-MS and its Evaluation by Isotope Dilution Thermal Ionisation Mass Spectrometry

A precise and simple method for the determination of lithium concentrations in small amounts of silicate sample was developed by applying isotope dilution-inductively coupled plasma-mass spectrometry (ID-ICP-MS). Samples plus a Li spike were digested with HF-HClO₄, dried and diluted with HNO₃, and measured by ICP-MS. No matrix effects were observed for ⁷Li/⁶Li in rock solutions with a dilution factor (DF) of 97 at an ICP power of 1.7 kW. By this method, the determination of 0.5 μg g^-1 Li in a silicate sample of 1 mg can be made with a blank correction of < 1%. Lithium contents of ultrabasic to acidic silicate reference materials (JP-1, JB-2, JB-3, JA-1, JA-2, JA-3, JR-1 and JR-2 from the Geological Survey of Japan, and PCC-1 from the US Geological Survey) and chondrites (three different Allende and one Murchison sample) of 8 to 81 mg were determined. The relative standard deviation (RSD) was typically < 1.7%. Lithium contents of these samples were further determined by isotope dilution-thermal ionisation mass spectrometry (ID-TIMS). The relative differences between ID-ICP-MS and ID-TIMS were typically < 2%, indicating the high accuracy of ID-ICP-MS developed in this study.     

Determination of the Trace Refractory Elements V, Nb and Ta in Environmental Samples by ICP-MS After Separation and Preconcentration with Nanometre-Sized Alumina Microcolumns Following Chemical Modification by Gallic Acid

Nanometre-sized alumina was chemically modified with gallic acid (GA) and used as a solid phase adsorption material for the determination of trace amounts of V, Nb and Ta in natural water, soil and stream sediment samples by inductively coupled plasma-mass spectrometry. The effects of pH, sample flow rate and volume, elution solution and interfering ions on the recovery of the analytes were investigated. The results showed that V, Nb and Ta could be adsorbed at pH 4.0 and recovered with 1 ml of 2.0 mol l^-1 HCl. Under optimised conditions, the adsorption capacity of GA-modified nanometre-sized Al₂O₃ was found to be 7.0, 8.9, 13.3 mg g^-1 for V, Nb and Ta, respectively. The limits of detection were as low as 0.25, 0.24 and 0.66 ng l^-1 for V, Nb and Ta, respectively with a concentration factor of fifty. The recovery of V, Nb and Ta for spiked water samples was between 85.7 and 116%. The developed method has also been applied to the determination of trace V, Nb and Ta in soil and stream sediment certified materials, and the determined values were in a good agreement with the certified values.     

Three Cobalt-Rich Seamount Crust Reference Materials: GSMC-1 to 3

A research project involving the preparation of three Co-rich crust reference materials (GSMC-1 to 3) has been preliminarily completed. The samples were collected from the eastern and central Pacific seamount zones and their main chemical composition is MnO₂. After the raw materials were dried in ambient air and at low temperature (60-100 C), they were ground in a ball mill to form a well-mixed powder. The proportion of particle size fractions of < 74 μm and < 3 μm was over 98% and 50% respectively. The homogeneity of the materials was tested using wavelength dispersive X-ray fluorescence spectrometry (WD-XRF). The relative standard deviation (% RSD) of the measurements for all the selected elements in forty sub-samples randomly taken from the bottles was less than 0.4%. Sixteen laboratories from Germany, Russia, France, Australia and China participated in the collaborative analysis programme. Fifty seven elements or constituents were analysed, and among those, forty six elements were certified in each sample. The sum of contents of the major and minor elements or components was 99.5% for GSMC-1, 99.6% for GSMC-2 and 99.2% for GSMC-3.     

Comparison of Pb Purification by Anion-Exchange Resin Methods and Assessment of Long-Term Reproducibility of Th/U/Pb Ratio Measurements by Quadrupole ICP-MS

A comparison between HBr-HCl and HBr-HNO₃ based anion chemistry is presented to test the efficiency of Pb purification in the preparation of samples for isotope ratio measurement by ICP-MS. It was found that the small advantages in yield and blank offered by the HNO₃-based method were more than compensated by the more effective matrix removal of the HCl-based method. Apart from very zinc rich matrices (e.g., sphalerite), a careful single pass purification using HBr and HCl removed more than 99.9% of the matrix. In preparation for the isotope ratio analysis, a small (2–5% m/v) liquid sample aliquot was analysed to determine U, Th and Pb concentrations by solution quadrupole ICP-MS. This allowed accurate prediction of the expected ion signal and permitted optimal spiking with Tl, if desired, for mass bias correction. Long-term results for international rock reference materials showed reproducibilities of better than 1% (Th/U) and 1.5% (U/Pb). For most geological applications, such analyses obviate the need for isotope dilution concentration measurements.     

Improvements in Digestion Protocols for Trace Element and Isotope Determinations in Stream and Lake Sediment Reference Materials (JSd-1, JSd-2, JSd-3, JLk-1 and LKSD-1)

Total dissolution is a critical step in geochemical analysis. Despite the number of published protocols, this issue still draws attention for sediment samples, which are particularly difficult to dissolve due to the common occurrence and high abundance of refractory phases such as zircon. We present tests of different chemical digestion procedures carried out on reference materials (RM) of stream (JSd-1, JSd-2 and JSd-3) and lake (JLk-1 and LKSD-1) sediments from the Geological Survey of Japan (GSJ) and the Canadian Certified Reference Material Programme (CCRPM). We demonstrate that the fusion technique is not appropriate for our studies as not all elements of interest were recovered and blank levels were too high to permit further Sr and Pb isotopic composition measurements. Similarly, conventional HF+HNO₃ dissolution methods were not efficient enough for detrital samples. Our preferred method involved using high pressure Teflon® vessel bombs in association with HClO₄. This protocol ensured a complete dissolution of the powder, as well as a complete recovery of trace elements. Moreover, blank levels were sufficiently low that Sr or Pb isotope compositions could be measured from the same mother solution. We also tested the homogeneity of RM powders by performing tests on various amount of powder.     

A Simple Method for Precise Determination of 23 Trace Elements in Granitic Rocks by ICP-MS after Lithium Tetraborate Fusion

Abstract. An improved alkali fusion method followed by HF-HNO₃-HC1O₄ treatment is performed for simultaneous determination of 23 trace elements (Sr, Y, Zr, Nb, Ba, Hf, Ta, Th, U, and REE) by ICP-MS in rock reference materials: basaltic rocks (JB-2, JB-3) and granitic rocks (JG-la, JG-2, JG-3). Our improved method offers several advantages including: (1) suppression of whitish precipitates probably composed of insoluble fluorides by addition of HCIO4, (2) simple and reliable preparation procedure, (3) instrument calibration which enables straightforward simultaneous multi-elemental analysis, and (4) the very low background levels by using pure lithium tetraborate flux. We obtained the analytical results with a reproducibility of mostly <2 % (1) for the basaltic rocks and <7 % for the granitic rocks. The higher relative standard deviation (RSD) values for granitic rocks may be attributed to sample heterogeneity of coarse-grained granitic rocks. The analytical results of the granitic rocks demonstrate that Zr and Hf abundances are consistent with the compiled values and that REE concentrations agree well with recently published data, suggesting that the Li₂B₄O₇ fusion method applied in the present study is suitable for the analysis of the granitic rocks.     

Determination of Major/ Minor and Trace Elements in Seamount Phosphorite by XRF Spectrometry

In this paper, a method developed to determine the major, minor and trace elements, including carbon and the four halogens, in seamount phosphorite involving a modern XRF spectrometry technique is described. Ultra-fine (99% v/v < 40 μm) powder samples (4 g) were directly pressed into pellets (Φ= 30 mm). For elements having an analytical line lower in energy than the energy of Fe Kα line absorption edge, the inter-element absorption-enhancement effects were corrected using an influence coefficient method. For the other elements, the matrix effects were corrected using the ratio of element peak to Rh Kα Compton peak (for I, Rh K|3 Compton peak was used instead). The relative standard deviation was smaller than 1.0% for the major elements (except C, Na and Cl). The detection limit levels of C, F, Cl, Br and I were 30, 20, 0.8, 0.2 and 0.3 (μg g⁻¹ respectively for 100 s count time of background. The accuracy of this method was tested by evaluating determinations on three certified reference materials. The direct analysis of major and minor elements in geological materials by pressed pellet without any chemical procedures makes XRF spectrometry a particularly environment-friendly analytical technique.