Data Transformation as a Means to obtain Reliable Consensus Values for Reference Materials

Two different methods for estimating modal values of skewed distributions have been applied to round robin data on reference materials. The first method involves polynomial fitting to a histogram, and the second is confined to data transformation to overcome the problems connected with treatment of data characterized by skewed distributions. The transformation method (Gamma) allows the construction of a confidence interval which is non-symmetrical with respect to the central value of skewed distributions.     

Two Reference Samples for Assessing Analytical Data Reliability in Geochemical Investigations

The planned procedure for developing two reference samples, coal ash from the Kansk-Achinsk basin, ZUK-1, and silt from Lake Baikal, BIL-1, is described.     

Chlorine in 27 Geochemical Reference Samples

27 reference samples have been analysed for Cl by automated photometric analysis following alkali fusion. The results are in general agreement with the compilation values listed. However, it is apparent that in the case of the six USGS samples included, values are generally lower than those previously quoted for photometric determinations, particularly for G-2 and AGV-1.     

Iodine Content of Some Geochemical Reference Samples

18 geoahenrical reference samples have been analysed for iodine using an automated photometric method. Few comparative values are available in the literature but of the six that are available four show good agreement with the data reported. In all but one case the values obtained are less than 0.3 ppm, the exception being a bauxite (B.C.S. 395) with 8.8 ppm I.     

Instrumental Neutron Activation Analysis by Collecting Only One Spectrum: Results For International Geochemical Reference Samples

Instrumental neutron activation analysis of rocks and minerals is currently done on basis of collecting 2 or 3 energy spectra. We have found that, by collecting one spectrum one week after irradiation, satisfactory results for the USGS and CRPG geochemical reference samples can be obtained.     

Reference Materials for Geochemical Studies: New Analytical Data by ICP-MS and Critical Discussion of Reference Values

Abundances of twenty four trace elements, including Y and fourteen rare earth elements (REE), are reported for eighty six geological reference materials and four proficiency testing samples. Analytical data were obtained by ICP-MS using solution nebulisation after mixed acid digestion (HF-HClO₄) under pressure. Analysed samples cover a wide range of element concentrations and mineralogical compositions, including samples for which there are few previously published data. Precision for elemental determinations in nearly 90% of the samples analysed is better than 5%. Accuracy, estimated by comparison with data from compilations is better than 6% for well characterized reference materials. Results obtained for samples that are low in trace elements are often significantly lower than compiled reference values. A critical discussion of the compiled data sets, especially for Y and the REEs, indicates that some reference values seem to be erroneous.     

Boron Contents in Selected International Geochemical Reference Samples

Boron concentrations have been measured in fifteen geochemical reference materials using prompt gamma neutron activation analysis. Replicate analyses of these samples provide an indication of the precision of the method under "normal'analytical conditions over an extended period of time.
La teneur en bore a été dosée dans quinze échantillons géochimiques de référence par l'activation neutronique avec "prompt gamma". L'analyse répétée de ces échantillons démontre, en général, une bonne précision de la méthode en analyse de routine.     

Gold Content of Eleven French Geochemical Reference Samples

The gold content of eleven French geochemical reference samples has been determined by a combined neutron-activation and fire assay method. These data represent the first reported low-level and high quality gold analyses for these reference samples.     

冀东土壤地球化学基准值特征及研究意义

通过系统的土壤深层（第Ⅰ环境）取样调查，研究并给出了冀东土壤中元素系列地球化学基准值及其基本特征，包括全区及不同景观区、不同流域、不同类型土壤中元素的地球化学基准值，为区域经济发展规划和资源与环境评价提供了实用的基础地球化学信息。     

First Co-Operative Study on Four Tropical Soil Samples and One Lateritic Bauxite (Suriname) Proposed as Geochemical Reference Samples

Five samples from Suriname have been analysed for their chemical composition by 18 laboratories. The proposed reference samples are four soil samples and one lateritic bauxite. The samples were analyzed for major and minor elements as well as for 36 trace elements. More data are needed for better characterization of these samples, particularly for trace elements.     

Multielemental Neutron Activation Analysis of Chinese Geochemical Reference Samples

The concentrations of 36 elements in geochemical reference samples issued by the Ministry of Geology and Mineral Resources of China were determined by neutron activation analysis. Three main variants of the technique, instrumental, epithermal, and nreirradiation separation neutron activation analysis (INAA, ENAA, PNAA), were employed in a systematic study of the samples by three laboratories: the Institute of Atomic Energy of the Academia Sinica (INAA, ENAA), the Institute of High Energy Physics of the Academia Sinica (INAA), and the Institute of Geophysical and Geochemical Prosnecting of the Ministry of Geology and Mineral resources (INAA,PNAA). Both long and short irradiations and both Ge(Li) and HPGe detectors were used. A supplementary software nackage for data processing was developed. About 81% of the data determined by neutron activation agreed with recomended values with in 15%.     

Instrumental Neutron Activation Analysis Of French Geochemical Reference Samples

Instrumental neutron activation analytical data, for eighteen trace elements (Ba, Co, Cr, Cs, Hf, Rb), Sb, Sc, Ta, Th, La, Ce, Nd, Sm, Eu, Tb, Yb, Lu), Hd₂O and Fe₂0₃ in eleven French geoche-mical reference samples are presented and discussed briefly.     

Instrumental Neutron Activation Analysis Of 37 Geochemical Reference Samples

37 geochemical reference samples, issued mostly by the U.S. Geological Survey and the "Centre de Recherches Pétrographiques et Géochi-miques", have been analysed for more than twenty trace elements using instrumental neutron activation technique. The results are compared with published data; in most oases, the agreement is good.     

荧光光度法测定化探标样中的铪

锆和铪的化学性质非常相似,要用简便方法分离这两个元素是困难的,用化学方法测定微量锆和铪也是困难的。Kouimtzis和Brookes曾经在这方面做了一些工作,在他们工作的基础上,我们确立了实验条件并应用于化探标些中锆、铪的测定。     

Instrumental Neutron Activation Analysis of Twenty-Nine International Geochemical Reference Samples

Results of measurements of twenty-seven elements, most of them in trace amounts, by Instrumental Neutron Activation Analysis (INAA) in twenty-nine international geochemical reference samples from Canada, U.S.A., Japan, France and South Africa, are reported and compared with available literature values. In general, our data agree well with literature values. The disagreement of our results (e.g., Zr in Canadian syenites and several trace elements in USGS ultrabasic rocks) with those reported by other workers is briefly discussed and ways of improving INAA are pointed out. The present report includes data on several trace elements for which existing data are rather scarce.     

Fluorine in Twenty-Two International Reference Rock Samples and a Compilation of Fluorine Values for the USGS Reference Samples

Fluorine in 22 international reference samples has been determined with an ion selective electrode following fusion with a Na₂bCO₃-ZnO mixture. To eliminate the effect of fluorine complexes in the solutions, the results presented are means of fluoride determinations from a standard calibration curve and from the method of standard addition. Together with these new determinations an updated compilation of USGS-I reference samples is presented.     

Mass Spectrometric Isotope Dilution Analyses Of Barium in Geochemical Reference Samples

Twenty-four geochemical reference samples have been analysed far barium using the stable isotope dilution technique. These include five CRPG, ten ANRT, six Nimroc and two CCRMP samples together with the Tonalite from Tanzania, Duplicate analyses have been made in each case and our values for barium are believed to be accurate to approximately 3 %. In general, our results are in good agreement with the published data except for Nimroc samples where our data are consistently lower than the presently accepted values. No evidence of sample inhomogeneities was observed in the present work.     

Mass Spectrometric Isotope Dilution Determination of Cadmium in Geochemical Reference Samples

Twenty seven geochemical reference samples have been analysed for cadmium using the stable isotope dilution technique. These include four USGS, one NBS, five CRPG, eleven ANRT and six NIMROC samples. Each sample has been analysed at least in duplicate.
The four USGS samples have previously been measured in this laboratory by Rosman and De Laeter, but the present results are believed to be more accurate than the earlier data. Our results for the other twenty three samples are much lower than most of the published data. There is also evidence of cadmium inhomogeneities in some of the samples.     

XRF Determination of 19 Trace Elements In International Geochemical Reference Samples

Routine XRF determination of 19 trace elements in 23 international standards using the method of Leake et al is examined. Agreement of results for 15 well-established international reference samples is generally good, showing that this method gives comparable results to other techniques. New trace element data using this method are presented for the 8 USGS III standards.     

Spectrophotometric Determination of Molybdenum and Tungsten in Forty Geochemical Reference Samples

The molybdenum and tungsten contents of 40 geochemical reference samples have been determined by a spectrophotometric procedure. The agreement between the present results and published data is generally good.