The determination of copper,lead, cadmium and zinc in human teeth by anodic stripping voltammetry

Differential pulse anodic stripping voltamrnetry and a hanging mercury drop electrode are used for the determination of copper, lead, cadmium and zinc in Norwegian teeth and pure hydroxyapatite. Special attention is given to the choice of decomposition procedure and the determination of the blank values. A complete dissolution of the tooth material and satisfactory blank values can be obtained by using decomposition with nitric acid in a Teflon bomb.     

A new procedure for extraction of collagen from modern and archaeological bones for 14C dating

Bones are potentially the best age indicators in a stratigraphic study, because they are closely related to the layer in which they are found. Collagen is the most suitable fraction and is the material normally used in radiocarbon dating. Bone contaminants can strongly alter the carbon isotopic fraction values of the samples, so chemical pretreatment for ¹⁴ C dating by accelerator mass spectrometry (AMS) is essential. The most widespread method for collagen extraction is based on the Longin procedure, which consists in HCl demineralization to dissolve the inorganic phase of the samples, followed by dissolution of collagen in a weak acid solution. In this work the possible side effects of this procedure on a modern bone are presented; the extracted collagen was analyzed by ATR-IR spectroscopy. An alternative procedure, based on use of HF instead of HCl, to minimize unwanted degradation of the organic fraction, is also given. A study by ATR-IR spectroscopic analysis of collagen collected after different demineralization times and with different acid volumes, and a study of an archaeological sample, are also presented.     

电感耦合等离子体质谱(ICP-MS)法测定矿石中的铼——三种前处理方法比较

电感耦合等离子体质谱(ICP-MS)法是目前最常用测定分散元素铼的分析手段,其样品前处理方式有酸溶、半溶法。综合比较目前常用的三种溶样方法:氧化镁半溶法、密闭酸溶法、四酸(硝酸、氢氟酸、高氯酸、盐酸)敞开+强氧化剂法,从数据准确度、称样量、样品分解程度、引入杂质、溶解时间、操作过程等方面综合考察方法的适用性,并探讨了铼的不同三种伴生矿物对结果的影响。结果表明,氧化镁半溶法准确度高,适合低含量样品的测定,但过程复杂,不适合大批量的样品;密闭酸溶法适合高含量样品测定;四酸敞开+强氧化剂法操作简单,溶矿时间较短,但因采用了高沸点酸高氯酸,使结果偏低。     

Experimental design in the optimization of a microwave acid digestion procedure for the determination of metals in biomorphic ceramic samples by inductively coupled plasma mass spectrometry and atomic absorption spectrometry

In the present paper, we have synthesized a biomorphic ceramic material from oak wood as biological template structure and infiltration with zirconia-sol. After the material characterization, we have optimized the sample dissolution by acid attack in an oven under microwave irradiation. Experimental designs were used as a multivariate strategy for the effect's evaluation of varying several variables. This article describes the development by response surface methodology (RSM) of a procedure for zirconium determination, and other ions, such as copper and nickel by inductively coupled plasma mass spectrometry (ICP-MS) and others, such as iron, calcium and magnesium determination by flame atomic absorption spectrometry (FAAS) in the synthesized sample after digestion. A full factorial design (3³) was used to find optimal conditions for the procedure through response surface study. Three variables (time, HNO₃ volume and HF volume) were regarded as factors and as response to the concentration of different metal ions in the optimization study.     

Production oriented method for the determination of rare earth and other trace elements in rocks by ICP-MS

The rare earth elements along with Y, Sc, Co, Hf, Nb, Rb, Ta, Th, Ti, U, V and Zr have been determined in ten standard reference materials and ten granitoid samples by inductively coupled plasma mass spectrometry (ICP-MS). Two digestion methods have been used: (a) dissolution with hydrofluoric-perchloric acid followed by fusion of the residue with lithium metaborate, (b) dissolution with hydrofluoric acid-perchloric acid followed by fusion with lithium metaboratesodium perborate and addition of hydrogen peroxide. An evaluation of the two decomposition methods and a comparison of the ICP-MS and X-ray fluorescence results have been carried out. In comparing the two digestion methods, method (b) gave more accurate results for Nb and Ta, and it has been applied to a rock geochemistry project covering whole Finland (about 7000 samples). The statistical stability of the method has been monitored by frequent analyses of reference material SDC-1 (Mica Schist, USGS).     

Production oriented method for the determination of rare earth and other trace elements in rocks by ICP-MS

The rare earth elements along with Y, Sc, Co, Hf, Nb, Rb, Ta, Th, Ti, U, V and Zr have been determined in ten standard reference materials and ten granitoid samples by inductively coupled plasma mass spectrometry (ICP-MS). Two digestion methods have been used: (a) dissolution with hydrofluoric-perchloric acid followed by fusion of the residue with lithium metaborate, (b) dissolution with hydrofluoric acid-perchloric acid followed by fusion with lithium metaboratesodium perborate and addition of hydrogen peroxide. An evaluation of the two decomposition methods and a comparison of the ICP-MS and X-ray fluorescence results have been carried out. In comparing the two digestion methods, method (b) gave more accurate results for Nb and Ta, and it has been applied to a rock geochemistry project covering whole Finland (about 7000 samples). The statistical stability of the method has been monitored by frequent analyses of reference material SDC-1 (Mica Schist, USGS).     

Microwave-assisted versus conventional decomposition procedures applied to a ceramic potsherd standard reference material by inductively coupled plasma atomic emission spectrometry

Inductively coupled plasma atomic emission spectrometry (ICP-AES) is a powerful, sensitive analytical technique with numerous applications in chemical characterization including that of ancient pottery, mainly due to its multi-element character, and the relatively short time required for the analysis. A critical step in characterization studies of ancient pottery is the selection of a suitable decomposition procedure for the ceramic matrix. The current work presents the results of a comparative study of six decomposition procedures applied on a standard ceramic potsherd reference material, SARM 69. The investigated decomposition procedures included three microwave-assisted decomposition procedures, one wet decomposition (WD) procedure by conventional heating, one combined microwave-assisted and conventional heating WD procedure, and one fusion procedure. Chemical analysis was carried out by ICP-AES. Five major (Si, Al, Fe, Ca, Mg), three minor (Mn, Ba, Ti) and two trace (Cu, Co) elements were determined and compared with their certified values. Quantitation was performed at two different spectral lines for each element and multi-element matrix-matched calibration standards were used. The recovery values for the six decomposition procedures ranged between 75 and 110% with a few notable exceptions. Data were processed statistically in order to evaluate the investigated decomposition procedures in terms of recovery, accuracy and precision, and eventually select the most appropriate one for ancient pottery analysis.     

Determination of Nb and Ta in Nb/Ta minerals by inductively coupled plasmas optical emission spectrometry using slurry sample introduction

The determination of Nb and Ta in Nb–Ta minerals was accomplished by slurry nebulization inductively coupled plasma optical emission spectrometry (ICP-OES), using a clog-free V-groove ceramic nebulizer. Samples were first wet-ground to appropriate particle sizes with narrow size distribution and 90% of the particles in the slurry were smaller than 2.32 μm in diameter. Subsamples were then dispersed in pH 9 aqueous solutions, and agitated in an ultrasonic bath for 15 min prior to analysis. Due to the lack of slurry standards matching well with the samples, calibration was simply carried out using aqueous solution standards. Results were compared with those obtained from a conventional fusion decomposition procedure and acid digestion procedures and a good agreement between the measured and referred values was obtained. The technique provided a good alternative for the rapid determination of Nb and/or Ta in their corresponding minerals.     

Analysis of the CCRMP Oka-2 rare-earth reference mineral of the britholite-apatite series by electrothermal atomic-absorption and inductively-coupled plasma atomic-emission spectrometry

The lanthanides and yttrium in the Canadian Certified Reference Materials Project (CCRMP) new rare-earth mineral reference material, Oka-2, were determined by electrothermal atomic-absorption and inductively-coupled plasma atomic-emission spectrometry (ICPAES) after sample decomposition with acids and separation of the rare-earth metals from phosphate and other matrix elements by precipitation as fluorides and oxalates. Thorium, yttrium and the common major and minor elements were determined by ICPAES after sample decomposition by fusion with lithium meta- and tetraborates and dissolution of the melt in a mixture of dilute nitric acid and ethylenediaminetetra-acetic acid solution. For comparison purposes, silicon, phosphorus, calcium, magnesium and iron were also determined by other methods. The results obtained are compared with other CCRMP values and with those obtained previously for a similar rare-earth mineral from the same geographical area. Oka-2 is considered to be a thorian intermediate member of the britholite—apatite series.     

Determination of structural modification in acid activated montmorillonite clay by FT-IR spectroscopy

The structural modifications and the Bronsted acid sites generated during the acid treatment of montmorillonite clay with varied concentration of sulphuric acid was determined using FT-IR spectroscopy. Octahedral sheet is affected at low acid concentration resulting into the dissolution of cations; among them Mg2+ cations are prone to dissolve than Fe2+/3+ and Al3+. Tetrahedral sheet is affected at higher acid concentration. The partial substitution of octahedral Al3+ by Mg2+ or Fe2+/3+ cations and the presence of other non-smectite minerals such as kaolinites was also been clearly identified, thus making FT-IR spectroscopy as a rapid technique for monitoring the structural features of montmorillonite clay.     

Accelerator mass spectrometry 14C determination in CO2 produced from laser decomposition of aragonite

The determination of (14)C in aragonite (CaCO(3)) decomposed thermally to CO(2) using an yttrium-aluminum-garnet doped neodymium laser is reported. Laser decomposition accelerator mass spectrometry (LD-AMS) measurements reproduce AMS determinations of (14)C from the conventional reaction of aragonite with concentrated phosphoric acid. The lack of significant differences between these sets of measurements indicates that LD-AMS radiocarbon dating can overcome the significant fractionation that has been observed during stable isotope (C and O) laser decomposition analysis of different carbonate minerals. The laser regularly converted nearly 30% of material removed into CO(2) despite it being optimized for ablation, where laser energy breaks material apart rather than chemically altering it. These results illustrate promise for using laser decomposition on the front-end of AMS systems that directly measure CO(2) gas. The feasibility of such measurements depends on (1) the improvement of material removal and/or CO(2) generation efficiency of the laser decomposition system and (2) the ionization efficiency of AMS systems measuring continuously flowing CO(2).     

Dissolution problems with botanical reference materials

Summary As part of the analytical research leading to the certification of the new Apple and Peach Leaves Standard Reference Materials (SRMs), a study was undertaken to evaluate different sample dissolution techniques for losses of analyte species. Possible loss mechanisms include absorption or adsorption of analyte elements at the walls of the sample decomposition vessels, and the formation or persistence of insoluble particulate material during sample dissolution. Results of this study indicated that significant fractions of some elements were present on particles after acid dissolution, despite visual indications that dissolution was complete. In addition, large amounts of some elements remained in the platinum crucibles used to fuse samples with lithium metaborate.     

热重分析-单滴微萃取-气相色谱-质谱结合傅里叶变换红外光谱考察咖啡酸的热解行为

采用热重分析-单滴微萃取-气相色谱-质谱(TG-SDME-GC-MS)联用系统和傅里叶变换红外光谱,研究了咖啡酸的热解行为。设定热重分析仪5 ℃/min的升温速率及400 mL/min的氮气流量,在160～360 ℃温度范围内,采用乙醇对热解逸出物质进行单滴微萃取,然后利用GC-MS分离分析,监测了咖啡酸5种主要热解逸出产物相对含量随温度升高的动态变化情况。使用傅里叶变换红外光谱分析了咖啡酸所对应各失重点固体剩余物的特征官能团变化情况。结果表明,咖啡酸热失重的主要原因是在240～360 ℃产生大量的邻苯二酚,在200～220 ℃热解产生4-乙基邻苯二酚。另外,咖啡酸在230 ℃下已完全裂解。该方法的建立为温度连续上升模式下的物质热解行为分析提供了借鉴和参考。     

Integrated scheme for micro-determination of iron oxidation states in silicates and refractory minerals

A mirco-analytical scheme incorporating four methods is described for the determination of iron(II) and iron(III) in both hydrofluoric acid-soluble and refractory minerals. The acid-soluble minerals are analyzed for FeO by direct constant-current potentiometric titration with potassium dichromate, and a separate solution is titrated similarly after Zn/Hg reduction to give total iron. The micro-determination of FeO in chromite and other refractory minerals involves dissolution in a cerium(IV)/phosphoric acid mixture and constant-current potentiometric and indirect titration of excess of cerium(IV) (phosphatocerate) with iron(II). Lithium tetraborate micro-fusion is required for measurement of total iron by atomic absorption spectrometry or spectrophotmetry. The average relative standard deviation ranged between 0.73 and 1.08%.     

Multivariate optimization of a microwave-assisted leaching procedure using dilute acid solutions,for FAAS determination of Cu,Fe, Mn,and Zn in multivitamin/multimineral supplements

This paper reports the development of a microwave-assisted procedure for leaching of copper, iron, manganese, and zinc from multivitamin/multimineral supplements by use of dilute acid before determination by flame atomic absorption spectrometry (FAAS). A Doehlert design was used to find optimum conditions for the procedure by use of response-surface methodology. Three variables (acid concentration in the leaching solution, irradiation time, and irradiation power) were used as factors in the optimization study for two acids, HCl and HNO₃. Final working conditions were established as a compromise between the optimum values for each analyte, taking into consideration the robustness of the procedure. The best leaching results were obtained with HNO₃ and the acid concentration, irradiation time, and irradiation power used were 0.70 mol L⁻¹, 15 min and 360 W, respectively. The accuracy of the optimized procedure was evaluated by comparison with a well-established closed-vessel microwave dissolution technique.     

CO2矿化反应基础研究 I.镁橄榄石和蛇纹石盐酸浸出动力学研究

对盐酸浸取镁橄榄石和蛇纹石的过程进行了研究,考察了酸浓度、浸取温度对镁浸出率的影响。结果表明,提高酸浓度和浸取反应温度能够提高镁橄榄石和蛇纹石中镁的浸出率。采用单粒级矿物原料浸出实验获得的动力学数据,利用收缩核模型分析了橄榄石和蛇纹石的镁浸出过程动力学,镁橄榄石浸出动力学属表面化学反应控制,而蛇纹石浸出反应为产物层扩散控制。两种矿物结构的差异影响镁浸出的难易程度,也决定了不同的浸出动力学行为。     

Determination of mercury in tuna fish tissue using isotope dilution-inductively coupled plasma mass spectrometry

Isotope dilution-inductively coupled plasma mass spectrometry (ID-ICP/MS) was applied to determine mercury in living tissue. Microwave digestion method using HNO₃/H₂O₂ media for the dissolution of solid sample was studied. The procedure for accurate determination of total mercury in tuna fish tissue sample by ID-ICP/MS is described. For the method validation, total Hg concentration in tuna fish CRM (BCR CRM 463) was determined by ID-ICP/MS after addition of ²⁰²Hg to CRM followed by acid decomposition of the spiked sample. This method was applied to the determination of Hg in tuna fish CCQM-P39 sample provided by IRMM (Institute for Reference Materials and Measurement, GEEL, Belgium) for the international comparison study.     

Comparison of wet microwave digestion methods of plant materials for the determination of metals by flame atomic absorption spectrometry

Microwave closed-system wet digestion procedures for plant samples were examined. Each procedure was tested with samples of tobacco and cabbage, and included digestion by the use of different acids composition, almost complete evaporation of the digest, and then dissolution of the residue in 1% nitric acid. Three microwave digestion programs that varied power, duration, and temperature were used. Closed-vessel reactions followed open-vessel reaction-delay time. Using flame atomic absorption spectrometry on the digests, four or five elements were determined to evaluate effectiveness, precision and accuracy of analytes extraction into solution. After a preliminary study of tobacco digests, the four most effective procedures were chosen, and detailed investigations were carried out on both tobacco and cabbage reference materials. Although all four of the final procedures were accurate, the most precise procedure, with the lowest errors of determination, was using reverse ‘aqua regia’ for tobacco and ‘aqua regia’ for cabbage.     

Determination of inorganic cations by capillary ion electrophoresis in Ilex paraguariensis (St. H.), a plant used to prepare tea in South America

A practical and economical capillary ion electrophoresis method with indirect UV detection at 214 nm was developed for determination of inorganic cations in plants of Ilex paraguariensis(St. H.) and their infusion known as mate tea, a very popular beverage in South America. A microwave digestion procedure was used to prepare the herbal plants, but the infusion was only diluted. The background electrolyte contained 6mM imidazole and 10mM alpha-hydroxyisobutyric acid, pH 4.0. The running voltage was 20 kV and temperature was 25 degrees C. K, Na, Ca, Mg, and Mn ions were quantitated, and linearity was demonstrated between 0.6 and 120 ppm. The results were in good agreement with those obtained by flame atomic absorption and emission spectrometry. Accuracy of the method was verified by comparison with Beech leaves CRM 100, a standard reference material. The high content of minerals and several oligoelements, especially Mn in mate tea, is considered to be of nutritional interest.     

Determination of lead in fly-ash from a garbage incinerator by atomic-absorption and x-ray fluorescence spectrometry

The lead content in fly-ash collected by an electrostatic precipitator has been determined by atomic-absorption spectrometry (AAS) after decomposition by four different leaching/dissolution techniques, and also determined by X-ray fluorescence spectrometry (XRFS) by the standard-addition method. The XRFS data were evaluated by non-linear regression since the standard additions affected the attenuation coefficient of the sample. Good agreement was obtained between the results obtained with AAS and XRFS. It is concluded that lead is quantitatively extracted by hot 1M nitric acid or treatment with hydrofluoric acid/nitric acid. Direct measurement of briquetted samples by XRFS is suggested for rapid monitoring of the lead content in fly-ash from garbage incineration.