重铬酸钾容量法测定地质样品中的有机碳

目前,地质样品中有机碳的测定方法有干烧法（高温电炉灼烧）和湿烧法（重铬酸钾氧化）两大类。另外还有ICP-AES法、微波消解法、过硫酸钾法、电导法、石墨电热消解法、比色法等,然而这些有机碳测定方法仍然存在许多不尽如人意的地方。干烧法要求实验条件苛刻,操作繁琐,不易掌握,受碳酸盐的干扰。湿烧法虽然操作比较简单,但方法受样品中还原性物质的干扰,如氯根、亚铁等,上述方法都有待完善和优化改进。如：探索因不同样品基体差异而产生的干扰元素消除方法;寻找更合适的指示剂;本文采 用重铬酸钾-容量法测定地质样品中的有机碳,在220±10℃恒温电热板上,用0.4 mol/mL重铬酸钾溶解样品。通过优化熔矿温度、熔矿时间、熔剂浓度的优化选择,进行了氯离子的干扰试验。样品中含氯化物低的样品通过加入0.1 g硫酸银消除,样品中含氯化物高的样品通过高温灼烧减量消除。氧化指示剂选用邻菲啰啉或苯二氨基苯甲酸。本方法适用于土壤、水系沉积物、岩石等地质调查样品中有机碳的测定,方法相对标准偏差（RSD）在0.80%～4.41%之间,准确度（RE）在-3.15%～+1.15%之间。通过标准物质验证,方法技术指标满足地质行业规范DZ/T0130.4-2006中有机碳的分析要求,建立了一种简单、快捷、经济、准确的测定地质样品中有机碳的测定方法,满足地球化学调查批量样品生产的需要。     

An Improved Method for the Determination of Bismuth in Geological Materials by Automated Hydride Generation Atomic Absorption Spectroscopy

Abstract

An improved, automated method for the determination of bismuth in geological materials at the sub-microgram per gram level is described. After a closed-vessel digestion using nitric, hydrochloric, and hydrochloric, and hydrofluoric acids and evaporation twice with perchloric acid, a hydrochloric acid solution of the sample is automatically mixed with masking and reducing agents, further acidified with hydrochloric acid, and finally reacted with sodium borohydride to form bismuthine (BiH₂). The bismuthine is then separated from the analytical stream using a modified phase separator and then decomposed in a quartz tube furnace positioned in the path of an atomic absorption spectrophotometer. Bismuth quantification is done using aqueous calibration standards and peak height measurements. Interferences are minimized, therefore allowing the analysis of most geological materials without the method of standard additions. The relative standard deviation of the digestion and instrumental procedure is 2.0% at 50 μg Bi/L. The reagent blank is 0.2 μg Bi/L. Results for 32 standard reference materials are presented, 14 of which do not have published B1 values.     

Determination of boron,beryllium and lithium in coal ash and geological materials by spark optical emission spectrometry

A method is described for the accurate and precise determination of boron, beryllium and lithium in coal ash and geological materials by a point-to-plane high-voltage spark optical emission spectrometric technique. A 200-mg sample is crushed and blended with graphite, copper oxide internal standard and cellulose powders, and briquetted. Synthetic calibration standards are prepared from spectrographically pure materials blended into graphite. Corrections are made for spectral interference by iron and silicon on boron. Accurate results are presented for certified reference materials. The precision of the method, about 5%, is superior to that obtained by d.c. arc optical emission.     

高温燃烧水解-离子色谱法测定煤中的氟和氯

建立高温燃烧水解-离子色谱法测定煤中氟和氯含量的方法。间隔测量煤标准物质和待测煤样,以煤标准物质特性量值的变化扣除系统漂移的影响,提高了测定结果的准确度和重复性。氟含量在0.042~2.018μg/mL范围内与其色谱峰面积呈良好的线性关系,线性相关系数r=0.995 8,检出限为0.011μg/g,测量结果相对标准偏差为6.32%(n=6);氯含量在0.046~2.292μg/mL范围内与其色谱峰面积呈良好的线性关系,线性相关系数r=0.999 8,检出限为0.010μg/g,测量结果的相对标准偏差为0.7%(n=6)。用该方法对煤标准物质进行测定,氟、氯测定结果与标准值一致。该方法简便快速,灵敏度高,结果准确,可用于煤中氟和氯含量的测定。     

Comparative study of activation analyses for the determination of trace halogens in geological and cosmochemical samples.

Halogens (fluorine, chlorine, bromine and iodine) were determined by activation analyses (neutron activation analysis (NAA), photon activation analysis (PAA) and prompt gamma-ray analysis (PGA)) for geological and cosmochemical solid samples. We studied how each analytical method was for the determination of trace amounts of halogens in rock samples. Radiochemical NAA (RNAA) showed the highest analytical reliability for three halogens (chlorine, bromine and iodine), whereas a set of four halogens (fluorine, chlorine, bromine and iodine) could be determined in principle by radiochemical PAA (RPAA) from a single specimen. Although it is a non-destructive method, PGA showed an analytical sensitivity for chlorine comparable to those of RNAA and RPAA.     

Determination of fluorine and chlorine in geological materials by induction furnace pyrohydrolysis and standard-addition ion-selective electrode measurement

Fluorine and chlorine in geological materials are volatilized by pyrohydrolysis at about 1150 degrees in a stream of oxygen (1000 ml/min) plus steam in an induction furnace. The catalyst is a 7:2:1 mixture of silica gel, tungstic oxide and potassium dihydrogen phosphate. The sample/catalyst mixture is pyrohydrolysed in a re-usable alumina crucible (already containing four drops of 1 + 3 phosphoric acid) inserted in a silica-enclosed graphite crucible. The absorption solution is buffered at pH 6.5 and spiked with 1.6 mug of fluoride and 16 mug of chloride per g of solution, to ensure rapid and linear electrode response during subsequent standard-addition measurement. The simple plastic absorption vessel has 99.5% efficiency. The 3s limits of detection are 5-10 mug/g and 40-100 mug/g for fluorine and chlorine respectively. The procedure is unsuitable for determining chlorine in coal.     

Applicability of capillary electrophoresis to the analysis of trace rare earth elements in geological samples.

This study developed a methodology to analyze trace rare earth elements (REEs) in geological materials by capillary electrophoresis (CE). Changed from dilute HNO3 into a water medium by heating, REE ions are detectable at approximately 2 ng mL(-1). In the presence of coexisting elements from geological samples, REE separations were carried out. After sample fusion with Na2O2 and interference separation with ammonium pyrrolidinedithiocarbamate chelate, REE analytes were coprecipitated with Mg(OH)2 at pH 8.5, and then prepared into a water medium for CE determination. Using the standard addition method, this protocol was validated by analyses with better than 5% precision. This method was applied to geological materials; the REE results are in consistence with their certified values. With electrokinetic injection, internal standard (IS) selected among lanthanides is a prerequisite of high-quality REE data. An approach was proposed to derive the IS content for further correcting its contribution from unknown samples.     

Certification of the chlorine content of the isotopic reference materials IRMM-641 and IRMM-642

The Slovak Institute of Metrology and the Institute for Reference Materials and Measurements have collaborated in the certification of the two chlorine reference materials IRMM-641 and IRMM-642. Until now no isotopically enriched chlorine isotopic reference material certified for isotopic composition and content has been available commercially. The isotopic reference materials IRMM-641 and IRMM-642 described herein are certified for isotopic composition and for chlorine content. The chlorine content of the reference material IRMM-641 was certified by use of high-precision argentometric coulometric titration at the Slovak Institute of Metrology. The base material used for IRMM-641 is NIST Standard Reference Material 975. The chlorine content of the reference material IRMM-642 was measured by isotope dilution, using negative thermal ionization mass spectrometry at the Institute for Reference Materials and Measurements. Both standard reference materials were prepared by dissolving NaCl in water. The reference material IRMM-641 contains 0.025022 +/- 0.00011 mol kg(-1) chlorine of natural isotopic composition with an n(37Cl)/n(35Cl) ratio of 0.31977 +/- 0.00082. The reference material IRMM-642 contains 0.004458 +/- 0.000028 mol kg(-1) chlorine with an n(37Cl)/n(35Cl) ratio of 0.01914 +/- 0.00088.     

石墨炉原子吸收光谱法测定地质样品中的痕量金

用活性炭吸附,于5％盐酸溶液中用甲基异丁基酮(MIBK)萃取金,采用斜坡升温和热解涂层石墨管技术进行地质样品中痕量金的石墨炉原子吸收光谱法测定,检出限为0．1ng/g。用该方法对标准物质进行测定,结果与标准值相符,测定结果的相对标准偏差为2．0％～6、9％(n=6)。     

Determination of Trace Chlorine in Fine Ceramics by ICP-AES Using Tungsten Boat Furnace Vaporizer and Exchangeable Sample Cuvette System as a Direct Solid Sampler

A new approach to simple solid sample digestion, subsequent vaporization, and introduction into an inductively coupled plasma was developed for the direct determination of chlorine in fine ceramic materials by atomic emission spectrometry. To each small sample cuvette made of tungsten, a powder sample was placed and weighed accurately. Following an addition of modifier solution, the cuvette was positioned on the tungsten boat furnace incorporated an electrothermal vaporizer. Then, the analyte in the sample cuvette was vaporized and introduced into the plasma; the major components of ceramic being retained. The solid ceramic samples were analyzed by using an external calibration curve prepared with the aqueous standard solutions. The detection limit of chlorine was estimated to be 0.71 ng, which corresponds to 59 ng g^?1 of the chlorine concentration in solid ceramic materials. The relative standard deviation was calculated to be 3.2%. The analytical results in various ceramic materials are described.     

岩石样品中43种元素的高分辨等离子质谱测定

以ＨＮＯ３和ＨＦ高压密封溶样,选择各元素浓度分布高低兼顾的国标ＷＢＧ０７１０３和ＷＢＧ０７１０５作参考标准,以高分辨ＩＣＰ－ＭＳ仪器测定岩石样品中４０余种元素,方法检出限在０．１～１８８ｎｇ／ｇ之间,各元素相对标准偏差（ＲＳＤ,ｎ＝６）多在５％以下,方法已用于批缇岩石样品分析。     

泡沫塑料动态快速分离富集金方法的研究

本文系统研究了泡沫塑料动态快速分离富集金的方法。对泡沫塑料柱的处理方法,再生及主要共存离子干扰的消除等均做了较详细的研究。提出了一种简便,不控速的金分离富集的方法。该法用于分析0.051～3.59g/t四种不同含量的金标样,结果与推荐值吻合,5次分析结果,相对标准偏差<5％,同时,可用泡沫塑料柱当天连续使用分析拿标样,回收率为93％—109％。     

Determination of rhenium in geological materials by radiochemical neutron-activation analysis

A neutron-activation method for the determination of rhenium in geological materials is described. Radiochemical separation, using Re-carrier and liquid-liquid extractions, yields (186)Re in a state of radiochemical purity. The gamma-ray activity of the radionuclide is counted with an NaI(Tl) crystal scintillation detector, and the chemical yield is determined spectrophotometrically. Results for the contents of rhenium in the standard rock W-1 and in nickeliferous lateritic profiles are reported. Particular problems arising in neutron-activation analysis for rhenium in lunar surface materials are discussed.     

Direct chlorine determination in crude oils by energy dispersive X-ray fluorescence spectrometry: An improved method based on a proper strategy for sample homogenization and calibration with inorganic standards

Official guidelines to perform chlorine determination in crude oil are (i) American Society for Testing and Materials (ASTM) D6470, which is based on the extraction of water from the oil and subsequent determination of the chloride by potentiometry, (ii) ASTM D3230, that measures the conductivity of a solution of crude oil in a mixture of organic solvents and (iii) US Environmental Protection Agency (EPA) 9075 that uses energy dispersive X-ray fluorescence spectrometry to quantify chlorine and it is applicable for the range from 200 μg g^− 1 to percent levels of the analyte. The goal of this work is to propose method to quantify lower amounts of chlorine in crude oil using energy dispersive X-ray fluorescence spectrometry using a simple calibration strategy. Sample homogenization procedure was carefully studied in order to enable accurate results. The calibration curve was made with standards prepared by diluting aqueous NaCl standard in glycerin. The method presented a linear response that covers the range from 8 to at least 100 μg g^− 1 of chlorine. Chlorine in crude oil samples from Campos Basin - Brazil were quantified by the proposed method and by potentiometry after extraction of chlorine from the oil. Results achieved using both methods were statistically the same at 95% confidence level.     

Pneumatoamperometric determination of chlorine in water

Free chlorine in water can be determined by acidifying the water sample, purging it with nitrogen and determining the chlorine present in the nitrogen stream with a gold porous electrode. The current response of gold porous electrode is related to the concentration of free chlorine by using a calibration curve. This pneumatoamperometric method gives results fully comparable to the standard o-toluidine photometric method used for water supplies. It is uninfluenced by the presence of other dissolved oxidants and requires only one milliliter of sample.     

Determination of chlorine and bromine in rocks by alkaline fusion with ion chromatography detection

This study describes the use of alkaline fusion by sodium peroxide to dissolve chlorine and bromine in rocks to produce a solution which, with appropriate pre-treatment, is suitable for analysis by ion chromatography. Results are given for a selection of sedimentary and igneous rocks. The accuracy of the fusion method is evaluated by analysis of Geological Survey of Japan reference materials. Additionally, a spike recovery test is performed to show that the fusion process is quantitative for chlorine and bromine. The results for chlorine are in the range 58–3860 mg kg⁻¹ and show good agreement both with results obtained by pyrohydrolysis with flow injection colorimetric detection and results obtained by aqueous leaching of the samples with ion chromatography detection. Results for bromine are in the range <3–4.5 mg kg⁻¹. Because of the relatively few data obtained in this study and the relative paucity of published data for reference materials, an assessment of the accuracy of the fusion method for bromine is more difficult. The limits of detection for this method are 36 and 3 mg kg⁻¹ for chlorine and bromine, respectively.     

An improved method for the determination of trace levels of arsenic and antimony in geological materials by automated hydride generation—atomic absorption spectroscopy

An improved, automated method for the determination of arsenic and antimony in geological materials is described. After digestion of the material in sulfuric, nitric, hydrofluoric and perchloric acids, a hydrochloric acid solution of the sample is automatically mixed with reducing agents, acidified with additional hydrochloric acid, and treated with a sodium tetrahydroborate solution to form arsine and stibine. The hydrides are decomposed in a heated quartz tube in the optical path of an atomic absorption spectrometer. The absorbance peak height for arsenic or antimony is measured. Interferences that exist are minimized to the point where most geological materials including coals, soils, coal ashes, rocks and sediments can be analyzed directly without use of standard additions. The relative standard deviation of the digestion and the instrumental procedure is less than 2% at the 50 μg l^-1 As or Sb level. The reagent-blank detection limit is 0.2 μg l^-1 As or Sb.     

Assessment of high precision,high accuracy Inductively Coupled Plasma-Optical Emission Spectroscopy to obtain concentration uncertainties less than 0.2% with variable matrix concentrations

The ability to obtain high precision, high accuracy measurements in samples with complex matrices using High Performance Inductively Coupled Plasma-Optical Emission Spectroscopy (HP-ICP-OES) was investigated. The Common Analyte Internal Standard (CAIS) procedure was incorporated into the High Performance Inductively Coupled Plasma-Optical Emission Spectroscopy method to correct for matrix-induced changes in emission intensity ratios. Matrix matching and standard addition approaches to minimize matrix-induced errors when using High Performance Inductively Coupled Plasma-Optical Emission Spectroscopy were also assessed. The High Performance Inductively Coupled Plasma-Optical Emission Spectroscopy method was tested with synthetic solutions in a variety of matrices, alloy standard reference materials and geological reference materials.     

Simplified method for the determination of Ru, Pd, Re, Os, Ir and Pt in chromitites and other geological materials by isotope dilution ICP-MS and acid digestion

A method for the determination of low Ru, Pd, Re, Os, Ir and Pt abundances in geological reference materials by isotope dilution inductively coupled plasma mass spectrometry (ICP-MS) after acid digestion in a high pressure asher (HPA-S) is presented. The digestion technique is similar to that using Carius tubes but easier to handle and reaches higher temperatures. Osmium can be determined as OsO4 with ICP-MS directly after digestion through a sparging technique. The remaining elements are preconcentrated by means of anion column chromatography. The resin is digested directly without elution leading to high yields but this causes problems if Zr is present at higher levels in the silicate rich materials. The analytical results for international platinum group element (PGE) reference materials, chromitite CHR-Bkg, basalt TDB-1 and gabbro WGB-1, are presented and compared with literature data, demonstrating the validity of the described method. Although higher in concentration, PGEs determined for reference material WGB-1 were worse than for TDB-1 indicating a more inhomogeneous distribution of the platinum group mineral phases. The low PGE abundance chromitite standard, CHR-Bkg, is likely to be homogeneous for Ru, Re, Os and Ir and is recommended as a reference material for the study of chromitites. Detection limits (3s x total procedure blank) range from 0.012 ng (Re and Os) to 0.77 ng (Pt), which could be further improved by applying higher quality acids.     

电感耦合等离子体质谱法(ICP-MS)测定土壤中的重金属元素

采用电感耦合等离子体质谱法(ICP-MS)测定了国家标准土壤样品中的部分重金属元素(Cd,Cu,Pb,Zn,Cr,Ni,Mo)的含量,其测定值与推荐值相符,准确度符合国家标准要求。各元素方法的检出限满足要求,相对标准偏差(RSD)介于0.91%~4.3%,加标回收率介于94%~106%。方法简便快速,结果准确,可以运用于大批量地质样品中的部分重金属元素含量的同时测定。