An interlaboratory study of potassium determination in rocks and minerals

Seven laboratories took part in this interlaboratory study which was part of an investigation of the flame-speetrometric determination of potassium in rocks and minerals suitable for potassium-argon age-measurement. Three of these laboratories determined potassium in the following five international reference rocks: tonalite T-1, basalt BCR-1, andesite AGV-1, granite G-2, and granodiorite GSP-1. The other five samples (with the number of laboratories analysing them in parentheses) were: a chlorite rock (7), an altered basic igneous rock (5), an altered basaltic andesite (5), a biotite (6) and a potassium feldspar (7). Details of sample preparation and methods of analysis are given; no laboratory used exactly the same method as any of the other six laboratories. Results have been examined by analysis of variance; larger relative between- and within-laboratory variations occurred for the two samples containing less than 0.1% potassium than for seven of the eight other (higher potassium) samples; between-laboratory variations for the basalt BCR-1 and, to a lesser extent, the andesite AGV-1, were high and of similar magnitude to those for the samples containing less than 0.1% potassium. The causes of any poor interlaboratory agreement in the present study are considered.     

A neutron-activation scheme developed for the determination of 42 elements in lunar material

A neutron-activation scheme designed for the determination of 42 elements in lunar rocks and fines is described. The scheme is based on seven different irradiations, four of which are followed by direct gamma-spectrometry, and three by radiochemical separation systems. The total sample consumption for duplicate analysis is about 800 mg. The scheme has been tested on basalt BCR-1, and results for this standard rock are presented. Analytical experience obtained from analyses of lunar samples and BCR-1 is discussed.     

Instrumental neutron and photon activation analyses of selected geochemical reference materials

Ten selected rock reference materials (USGS diabase W-1, basalt BCR-1, andesite AGV-1, granite G-2, granodiorite GSP-1, and CRPG basalt BE-N, granite GS-N, trachyte ISH-G, serpentine UB-N, glass standard VS-N) were analyzed by instrumental neutron and photon activation analyses. The results have been evaluated on average for the entire set of samples to detect possible systematic deviations of the determined values from the reference values. Out of 47 elements determined, 43 elements have been determined with reasonable agreement (deviation < 10% on average) with the reference values. Au could not be determined because of a high blank from packaging polyethylene foil. Systematically higher Dy and lower Ho and Tm (by about 20% on average) in the present results require further investigation. In several cases, reasons for greater differences between the determined and recommended values could not be traced in the procedures used within the study. The most suspect is the recommended value for W in the CRPG BE-N basalt, which is twenty-five times higher than the present value, probably due to inconsistent contamination from a W carbide mill used in production of this reference material.     

Precise determination of rare earth elements in rocks by neutron activation analysis

A pre-irradiation group separation method has been developed for the neutron activation analysis of rare earth elements (REE) and Ba in silicate rocks. REE and Ba were quantitatively separated from other elements by cation exchange column method. The chemical yield of each separation was monitored with Pr added to the sample powder before decomposition. The accuracy and precision were tested by repeated analyses of JB-1 and one analysis of BCR-1. In addition, it was found that REE distribution in a granitic rock powder was inhomogeneous and therefore special care must be taken for the sampling of granitic rock powders.     

Determination of rare earths in silicate rocks by epithermal neutron activation and a simple group separation

The determination of nine rare earth elements in rock samples by epithermal neutron activation, followed by a simple group-separation procedure and Ge(Li) γ-ray spectrometry, is described. This method is found to be advantageous for the determination of Nd, Gd, Ho, Er and Lu by means of the short-lived nuclides¹⁴⁹Nd,¹⁵⁹Gd,¹⁶⁶Ho,¹⁷¹Er and^176m Lu. Precision for La, Sm and Eu is similar to that of thermal neutron activation, that for Dy is worse. Samples of the standard rocks, basalt BCR-1 and granite G-2, were analyzed by this procedure and the results obtained are compared with previously reported data.     

Multielement analysis by sequential instrumental and radiochemical neutron activation

We measured 37 elements in six USGS geological camples and one NBS biological orchard leaf (OL) sample, using sequential INAA and radiochemical group separation coupled with high resolution, high efficiency Ge(Li), and a Ge(Li) with anticoincidence shields. The elemental concentrations in these samples vary over three orders of magnitude. Our results agree very well with the reported values. The rare earth values in PCC-1 are 2–4 times lower than the reported values. Precise REE patterns are defined in USGS samples, which are characteristic of the total rock types. The REE pattern in OL is identical to the mineral apatite. In addition to the possibility that OL may be contaminated by local soil, it is also possible that the uptake of REE trace elements by plants from soil is perhaps dominated by accessory mineral such as apatite, or plants take up the REE from bulk soil in a preferential manner as a smooth function of the REE ionic radii.     

Determination of ultra-trace rare earth elements in chondritic meteorites by inductively coupled plasma mass spectrometry

A method for the direct determination of ultra-trace rare earth elements (REE) in seven Chinese chondritic meteorites by inductively coupled plasma mass spectrometry (ICP-MS) was developed. Samples were digested with a mixture of HF+HNO₃ acids in Teflon pressure bomb. The accuracy and precision of the method were assessed by the analysis of four standard reference materials including one chondrite (Allende) and three basalts (BCR-1, BHVO-1 and W-2), the results obtained in this study agree quite well with the recommended values. The reproducibilities (expressed as RSD) of samples were less than 5%.     

Rapid sample digestion by fusion and chemical separation of Hf for isotopic analysis by MC-ICPMS

A new method for rapid sample digestion and efficient chemical separation of Hf and REE from rock samples for precise isotopic analysis is presented. Samples are digested by fusion in the presence of a lithium borate flux at 1100 °C and dissolved whilst molten in dilute nitric or hydrochloric acid. Prior to chemical separation using ion exchange techniques, Li and B from the flux material and Si from the sample are separated from the remaining major elements, REE and high field strength elements (HFSE) in the sample by Fe-hydroxide co-precipitation. The chemical separation of Hf is a two-stage procedure designed to first remove the remaining matrix elements (e.g. Fe, Ba) in the sample using standard cation exchange techniques, followed by separation of Hf from the REE and HFSE on TEVA extraction chromatographic resin. Hf yields are >90% and total procedural blanks are ca. 50 pg. Hf isotope ratios of a synthetic standard solution and replicate digestions of international rock standards BHVO-1 and BCR-1 measured on multi-collector inductively coupled plasma mass spectrometer (MC-ICPMS) reproduce similarly to ≤50 ppm (2 S.D.). The following elemental ratios are routinely obtained for elements, which interfere isobarically or may affect the ionisation and/or fractionation behaviour of Hf during analysis: ¹⁷⁶Yb/¹⁷⁶Hf<0.0001; ¹⁷⁶Lu/¹⁷⁶Hf<0.00001; Ti/Hf<0.05. This technique also provides a means of separating Nd from the REE fraction for isotopic analysis and, potentially, may be adapted for measurement of Lu/Hf ratios by isotope dilution techniques.     

吉林夹皮沟金矿带的稀土元素地球化学研究

为了解吉林夹皮沟金矿带的成矿期次,利用稀土元素的示踪性,对夹皮沟金矿带含矿石英脉、花岗岩及变质地层斜长角闪岩等21个样品进行稀土元素含量测定。测定结果表明,石英脉ΣREE=19.12×10-6～147.57×10-6,δEu=0.61～1.22,平均值0.89,具弱的负Eu异常;太古代花岗岩ΣREE=121.40×10-6～157.32×10-6,δEu=0.87～1.09;中生代花岗岩ΣREE=69.78×10-6～90.95×10-6,δEu=0.94～1.02,LREE/HREE比值分别为11.51～14.12和14.16～16.73,后者轻重稀土分馏程度略高于前者;变质围岩ΣREE=22.40×10-6～275.86×10-6,δEu=0.75～5.79,平均值2.30,具明显的正Eu异常。三者都具有轻稀土富集的平滑稀土配分模型。结合其区域地质背景、流体包裹体和稀土元素特征,得出夹皮沟金矿存在两期成矿作用,分别对应于太古代成矿花岗岩岩浆作用及中生代燕山期花岗岩岩浆作用。太古代首次富集成矿,中生代燕山期叠加成矿并扩大成矿规模,成矿时代分别为2475～2469 Ma和170～160 Ma;结合稀土特征研究及包裹体研究,成矿流体以岩浆热液流体为主,遭受轻微地层变质热液混染,中生代成矿流体混染作用更强烈。     

New application of microwave digestion-inductively coupled plasma-mass spectrometry for multi-element analysis in komatiites

A new method using microwave digestion combined with inductively coupled plasma-mass spectrometry (ICP-MS) was studied to analyze the elemental composition of a variety of komatiites samples. Microwave digestion consisted in two-stage heating and pressurizing acid treatments for maximum dissolution of the samples. We report here different quality control measurements (external and internal calibration, monitoring of reference materials) which involve standard deviation calculations and recovery examinations in order to test the precision and accuracy of the analytical procedure. Data for 17 elements (Na, P, K, T, V Cr, Mn, Co, Ni, Cu, Zn, Zr, Pb, Al, F, Ca and Mg) in eight komatiite samples and two USGS basalt reference samples (BCR-2 and BHVO-2) are presented. We evaluate our new digestion and instrumental procedure. The element concentration obtained for BCR-2 and BHVO-2 agreed well with the certified values, the relative standard deviations were lower than 5% and recoveries were good. Our analytical results demonstrate that it reproduces accurately the concentrations of minor and trace elements in komatiites. The ease of digestion of the samples and the speed (less than 12 h) to digest the komatiite material makes this technique an efficient method to be used easily and routinely for preparing and analyzing komatiites samples for multiple elements determination.     

Trace rare earth element analysis of IAEA Hair (HH-1), Animal Bone (H-5) and other biological standards by radiochemical neutron activation

A radiochemical neutron activation analysis using a rare earth group separation scheme has been used to measure ultratrace levels of rare earth elements (REE) in IAEA Human Hair (HH-1), IAEA Animal Bone (H-5), NBS Bovine Liver (SRM 1577), and NBS Orchard Leaf (SRM 1571) standards. The REE concentrations in Human Hair and Animal Bone range from 10^–8 g/g to 10^–11 g/g and their chondritic normalized REE patterns show a negative Eu anomaly and follow as a smooth function of the REE ionic radii. The REE patterns for NBS Bovine Liver and Orchard Leaf are identical except that their concentrations are higher. The similarity among the REE patterns suggest that the REE do not appear to be fractionated during the intake of biological materials by animals or humans.     

Trace element determination in rocks and sediments by neutron activation analysis

Neutron activation analysis (NAA) is one of the most used analytical techniques for trace element determination in rocks, because time consuming operations are avoided. We have analyzed different types of USGS reference materials (G-2, GSP-1, BHVO-1, STM-1, GXR-3, GXR-4, GXR-5), using both thermal (TNAA) and epithermal neutrons (ENAA). ENAA has been used to reduce interferences due to Sc-46 and to other high activities. The following elements have shown an improvement when analyzed by ENAA: Ba, Cs, Gd, Rb, Sb, Sr, Ta, Tb, Th, Tm, U, Yb, Zr; better results were found for Ce, Co, Cr, Eu, Fe, Hf, La, Lu, Na, Nd, Sc, Zn with TNAA. The accuracy of both methods has been tested comparing our results with some published values. The agreement is in general very good. The precision also is satisfactory, being for many elements better than 10%. After these tests, a study on some rock samples from the basaltic plateau of Kenya, east of Gregory Rift, has been performed by ENAA. Among the elements determined in this work, the rare earch elements (REE) can give significant petrogenetic information, by means of their distribution and fractionation in the rocks. The main parameters investigated are the degree of fractionation of light (La to Eu) relative to heavy (Gd to Lu) REE and the occurence of Eu anomalies, when the REE concentrations are compared to chondritic values. The evaluation of detection limits by TNAA has been performed for REE in sediment samples from Thyrrenian Sea (Central Italy).     

Rare earth element patterns in ultramafic rocks of the Schist Belt of Southwestern Nigeria by instrumental neutron activation analysis

24 Ultramafic rock samples from 3 different areas of the Schist Belt of Southwestern Nigeria were analyzed for 11 rare earth elements (REE) by instrumental neutron activation analysis (INAA). REE patterns of the ultramafic rocks are similar for the 3 different areas, and the REE abundances are smaller than for other types of rocks from the same areas. However, the moderate fractionation between LREE and HREE observed for these samples is unusual for ultramafic rocks. Some geochemical implications of the results are discussed.     

Cluster analysis of the elemental composition of five austrian peats

The elemental composition of peat depends on the plant residues from which the peat was formed. The concentrations of 45 elements were determined for five peat samples by plasma emission spectrometry. Literature data on the composition of three bogs was added. The elemental abundances of six rock or soil categories, the elemental compositions of several peat-forming plants, and the results of the elemental analyses of bog samples, were examined by the SIMCA method. A clear difference was found between fens and raised bogs. Factor analysis of the elemental compositions shows that the concentrations of most of the elements reflect their natural abundance in the surrounding region. Some concentrations are influenced by anthropogenic pollution, e.g. lead, and by plant metabolism. The cluster analysis together with the training sets shows the degree of the deposition of mineral material from adjacent rivers and the type of plant growth which formed the peat.     

The non-destructive determination of REE in fossilized bone using synchrotron radiation induced K-line X-ray microfluorescence analysis

The sensitivity and applicability of the synchrotron radiation induced X-ray microfluorescence (μ-SRXRF) spectrometer at the Hamburg synchrotron laboratory Hasylab for the determination of the distribution of trace concentrations of rare-earth elements (REE) in fossilized bone are discussed and critically compared to those of other trace analytical methods such as instrumental neutron activation analysis (INAA) and LAMP-ICPMS (laser ablation microprobe inductively-coupled plasma mass spectrometry). Measurements were carried out on two bone samples from contrasting terrestrial depositional environments at Olduvai Gorge (Tanzania). Results indicate that the microdistribution of the REE in these biological materials is not homogeneous and that the relative abundance of these elements can provide information on the palaeoenvironment during the fossilization process. The heterogeneous distribution of the REE can be determined in a quantitative and completely non-destructive manner provided the concentrations of individual REE are above 10 μg/g.     

Comparative study on retardation behavior of Cs in crushed and intact rocks: two potential repository host rocks in the Taiwan area

This study investigates sorption and diffusion of Cs in two potential host rocks (granite from Kinmen Island and basalt from Penghu Island) by using batch and through-diffusion methods in order to establish a reliable safety assessment methodology. These methods were applied to crushed and intact rock samples to investigate the actual geological environment. According to solid-phase analysis, including X-ray diffraction, elemental analysis, auto radiography, and polar microscopy, the sorption component primarily contained iron?Cmagnesium (Fe?CMg) minerals in basalt and granite. Moreover, the distribution coefficient (K _d) of Cs in various concentrations (~10^?2?C10^?7?M) obtained from batch tests indicated a higher sorption capacity in basalt than that in granite because of the 10% Fe?CMg mineral content. The diffusion of Cs in both crushed granite and basalt reached steady state after 110?days, and the apparent diffusion coefficients (D _a) were 2.86?×?10^?11 and 1.82?×?10^?12?m²/s, respectively. However, the value of D _a for Cs in intact rocks was estimated to be 1.45?×?10^?12?m²/s in granite and 0.56?×?10^?12?m²/s in basalt, lower than the values obtained using crushed rocks. In addition to the microporous structure (major sorption minerals), it showed that the major retardation of Cs depended on the porosity (??) of compacted media, according to through-diffusion tests. In fact, the solid/liquid (S/L) ratio decreased as is the case when switching from batch to column experiments and the sorption effect on minerals became even more negligible in retardation of radionuclide migration.     

Contamination of Rock Samples by Laboratory Grinding Mills

We have measured the contamination of samples of granite, quartz porphyry, greenstone and dolerite after grinding them in steel and cemented carbide grinding mills. The steel mill contaminated the granite with Fe. The cemented carbide mill contaminated all samples with W and Co, and the granite and quartz porphyry with Ta. Contamination during grinding is proportional to the free quartz content of the rock and to the grinding time.     

Analysis of low levels of rare earths by radiochemical neutron activation analysis

A procedure for the radiochemical neutron-activation analysis for the rare earth elements (REE) involves the separation of the REE as a group by rapid ion-exchange methods and determination of yields by reactivation or by energy dispersive X-ray fluorescence (EDXRF) spectrometry. The U. S. Geological Survey (USGS) standard rocks, BCR-1 and AGV-1, were analyzed to determine the precision and accuracy of the method. We found that the precision was ±5–10% on the basis of replicate analysis and that, in general the accuracy was within ±5% of accepted values for most REE. Data for USGS standard rocks BIR-1 (Icelandic basalt) and DNC-1 (North Carolina diabase) are also presented.     

Radiochemical neutron activation analysis of individual rare earth elements in monazites from different geological environments

Radiochemical neutron activation analysis /RNAA/ has been applied for the determination of individual rare earth elements /REE/, except Tm, in 8 Indian monazites and one each from Malaysia and Thailand. Because of the very low amounts of heavy rare earths /HREE/ compared to light rare earths /LREE/ in monazite, HREE from Ho onwards have been determined only after the separation of the heavy and light rare earth fractions in the irradiated monazite samples. The results indicate significant variations in REE contents from Eu to Lu among different monazite samples. The chondritic normalized REE patterns of all the samples show a prominent negative Eu anomaly with different slopes at the heavy rare earth end. All the individual REE, except Tm, have been reported for the first time in various Indian monazites.     

Determination of rare earths and other trace elements in samples of Antarctica by neutron activation analysis

The concentrations of REE and other trace elements have been determined in samples of Antarctica by Instrumental Neutron Activation Analysis (INAA). The samples were collected from the West Lake area near Great Wall Station. The samples include sediment, residual plants, rock and soil taken from the bottom of the lake to 3.4 m deep. The amounts of samples were very rare. In order to get more information, reactor NAA using both short and long irradiations with K₀ standardization has been adopted. Nine rare-earth elements (REE) namely La, Ce, Nd, Sm, Eu, Tb, Dy, Yb, and Lu as well as other trace elements (As, Au, Ba, Br, Co, Cr, Hf, Sc, Se, Th, V, Zn) have been determined. The concentrations and distribution patterns of REE in the samples have been given.