Certified Reference Material

A new method for the electrothermal atomic absorption spectrometric determination of vanadium in milk and infant formulas using suspensions to avoid the need for previous dissolution of samples is described. Sensitivity is improved by a procedure based on preconcentration and removal of the matrix, using ionexchange (Dowex 1X8-100). Suspensions of 15% (m/v) infant formula samples were prepared in a medium containing 0.05 M sodium citrate (pH 7.2) and passed through the ion exchange column. Vanadium was eluted from the column using 1 M hydrochloric acid and injected in the graphite furnace using a mixture of hydrofluoric acid plus magnesium nitrate as chemical modifiers. Calibration was carried out using multiple injection and aqueous standards prepared in the same medium. Detection limits were 0.2 ng g -1 for infant formulas and 0.02 g L -1 for cow milk samples. The reliability of the procedure was checked by comparing the results obtained with those found using a previous mineralization stage and by analyzing five certified reference materials.

The laboratory measurement of cardiac troponin (cTn) concentration is a critical tool in the diagnosis of acute myocardial infarction (MI). Current cTnI assays produce different absolute troponin numbers and use different clinical cut-off values; hence cTnI values cannot be interchanged, with consequent confusion for clinicians. A recent Australian study compared patient results for seven cTnI assays and showed that between-method variation was approximately 2-to 5-fold. A major reason for poor method agreement is the lack of a suitable common reference material for the calibration of cTnI assays by manufacturers. Purified complexed troponin material lacks adequate commutability for all assays; hence a serum-based secondary reference material is required for cTnI with value assignment by a higher order reference measurement procedure. There is considerable debate about how best to achieve comparability of results for heterogeneous analytes such as cTnI, whether it should be via the harmonisation or the standardisation process. Whereas harmonisation depends upon consensus value assignment and uses those commercial methods which give the closest agreement at the time, standardisation comes closer to the true value through a reference measurement system that is based upon long-term calibration traceability. The current paper describes standardisation efforts by the International Federation of Clinical Chemistry and Laboratory Medicine Working Group on Standardization of cTnI (IFCC WG-TNI) to establish a reference immunoassay measurement procedure for cTnI of a higher order than current commercial immunoassay methods and a commutable secondary reference material for cTnI to which companies can reference their calibration materials.

The in£uence of the freeze-drying process on the recovery of 12 chlorobiphenyl standards spiked in a wet candidate reference material ( mussel ) was investigated. Losses of spiked amounts tended to reduce with increasing number of chlorine atoms in the molecule. The aqueous phase in wet materials in combination with small volumes of organic solvents introduced by spiking may serve as an intermediate in the loss processes observed during freeze-drying, facilitating differential losses of spiked surrogate standards as well as analytes originally present in the material. Overall losses will be determined both by the amount of polychlorinated biphenyls stored in the aqueous phase ( solubility ) and by evaporation from the aqueous and tissue phases ( vapour pressure ) in a kinetic and complex way. Hence, recovery ¢gures for surrogate standards thus obtained may lead to an overestimation of the actual ef¢ciency of the analytical procedure for biologically bound polychlorinated biphenyls.

An inductively coupled plasma mass spectrometry (ICP-MS) method for elemental impurities determination in components used for parenteral nutrition solutions is proposed. Solutions of amino acids (10% m/v), glucose (50% m/v) and lipids (20% m/v) were analyzed. Arsenic, Cd, Cu, Pb and Mo were determined by ICP-MS operated at standard mode, whilst pneumatic nebulization was used for introducing the sample solution into the ICP. Mercury was determined using cold vapor generation (CVG) coupled to ICP-MS. Chromium, Mn, Ni and V were determined by means of dynamic reaction cell-inductively coupled plasma mass spectrometry (DRC-ICP-MS), while ammonia was used as reaction gas. The operational conditions of each technique were optimized in order to achieve better sensitivity, precision and accuracy. The influence of the sample matrix, mainly carbon, on all investigated elements was evaluated. The use of DRC was effective to reduce interferences on Cr, Mn, Ni and V determination. The other investigated elements (As, Cd, Cu, Pb, Mo and Hg) were determined directly in the samples, which were properly diluted. Results obtained were in good agreement (between 96 and 103%) with certified values (certified reference materials of water were analyzed), at the same time as the relative standard deviation was lower than 5%. Sample throughput was relatively high (up to 30 samples of components used for parenteral nutrition solution could be analyzed per hour). In this way, the proposed method can be recommended for routine analysis.

Bromine and iodine determination was performed in carbon nanotubes (CNTs) by inductively coupled plasma mass spectrometry (ICP-MS) after sample preparation using pyrohydrolysis. Samples of CNTs (up to 500 mg) were mixed with 750 mg of V 2 O 5 and heated at 950 °C during 12.5 min in a quartz tube under water vapor and air. The main operational conditions of pyrohydrolysis (carrier gas, absorbing solution, heating time, sample mass and use of V 2 O 5 ) were evaluated. Accuracy was evaluated using certified reference materials (CRM) with similar matrix and also by comparison of results obtained after digestion of samples by microwave-induced combustion (MIC) and determination by ICP-MS. Agreement with CRM values was higher than 97% for Br and better than 96% in comparison with reference values (MIC/ICP-MS) of Br and I in CNTs samples. The limit of detection of the method for Br and I determination by ICP-MS was 0.05 and 0.004 μg g -1 , respectively. Using a relatively simple and low cost pyrohydrolysis apparatus up to four samples can be processed per hour. The pyrohydrolysis sample preparation procedure is easy to be performed and provide a clean solution for analysis by ICP-MS, which is very attractive for Br and I control in CNTs.

The National Metrology Institute of Japan (NMIJ) in AIST has been studying the laser flash method in order to establish the SI traceable thermal diffusivity standard. We have developed key technologies to reduce uncertainty in laser flash measurements. This time we carried out an uncertainty evaluation on the laser flash measurement in order to determine the thermal diffusivity value of IG-110, a grade of isotropic high-density graphite, as a candidate reference material. Thermal diffusivity on the laser flash method is derived quantity from a specimen thickness and a thermal diffuse time. And thermal diffusivity values of materials are a function of temperature. The measurement system is also composed of three units corresponding to each quantities, length, time, and temperature. Then we checked and calibrate our measurement system and estimated the uncertainty of a measurement result.

Polar betacyanin pigments together with betaxanthins from ripe cactus fruits of Hylocereus polyrhizus (Cactaceae) were fractionated by means of preparative ion-pair high-speed countercurrent chromatography (IP-HSCCC) also using the elution-extrusion (EE) approach for a complete pigment recovery. HSCCC separations were operated in the classical 'head-to-tail' mode with an aqueous mobile phase. Different CCC solvent systems were evaluated in respect of influence and effectiveness of fractionation capabilities to separate the occurring pigment profile of H. polyrhizus. For that reason, the additions of two different volatile ion-pair forming perfluorinated carboxylic acids (PFCA) were investigated. For a direct comparison, five samples of Hylocereus pigment extract were run on preparative scale (900 mg) in 1-butanol-acetonitrile-aqueous TFA 0.7% (5:1:6, v/v/v) and the modified systems tert.-butyl methyl ether-1-butanol-acetonitrile-aqueous PFCA (2:2:1:5, v/v/v/v) using 0.7% and 1.0% trifluoroacetic acid (TFA) or heptafluorobutyric acid (HFBA) in the aqueous phase, respectively. The chemical affinity to the organic stationary CCC solvent phases and in consequence the retention of these highly polar betalain pigments was significantly increased by the use of the more lipophilic fluorinated ion-pair reagent HFBA instead of TFA. The HFBA additions separated more effectively the typical cacti pigments phyllocactin and hylocerenin from betanin as well as their iso-forms. Unfortunately, similar K D ratios and selectivity factors ˛around 1.0-1.1 in all tested solvent systems proved that the corresponding diastereomers, 15S-type pigments cannot be resolved from the 15R-epimers (iso-forms). Surprisingly, additions of the stronger ion-pair reagent (HFBA) resulted in a partial separation of hylocerenin from phyllocactin which were not resolved in the other solvent systems. The pigments were detected by means of HPLC-DAD and HPLC-electrospray ionization-MS using also authentic reference materials.

A downscaled solid phase (SPE) device applicable for sample preparation prior to ICP-MS monitoring, have been constructed making use of the lab on a chip concept. Standard photolithography and wet chemical etching were used to fabricate glass microfluidic devices accommodating three microchannels, each of them incorporating a defined section that could be packed with SPE materials; selective chelating resin. The microfluidic device was interfaced with the ICP-MS instrument throughout a low flow rate concentric nebuliser using a Teflon connector, and coupled with a flow injection manifold delivering samples and reagents via a manually operated splitting valve. The feasibility of the miniaturized prototype to perform SPE of trace metals was proved by analyzing trace metals, Cd, Co, and Ni, in seawater reference materials; CASS-2 and SLEW-1. The obtained result was in good agreement with the certified values. The device could be used as a remote miniaturized sample treatment for field work.

Monitoring of BCR-ABL transcripts has become established practice in the management of chronic myeloid leukemia. However, nucleic acid amplification techniques are prone to variations which limit the reliability of real-time quantitative PCR (RQ-PCR) for clinical decision making, highlighting the need for standardization of assays and reporting of minimal residual disease (MRD) data. We evaluated a lyophilized preparation of a leukemic cell line (K562) as a potential quality control reagent. This was found to be relatively stable, yielding comparable respective levels of ABL, GUS and BCR-ABL transcripts as determined by RQ-PCR before and after accelerated degradation experiments as well as following 5 years storage at À201C. Vials of freeze-dried cells were sent at ambient temperature to 22 laboratories on four continents, with RQ-PCR analyses detecting BCR-ABL transcripts at levels comparable to those observed in primary patient samples. Our results suggest that freeze-dried cells can be used as quality control reagents with a range of analytical instrumentations and could enable the development of urgently needed international standards simulating clinically relevant levels of MRD.

IRMM-443 re-groups a set of six European Reference Soils (EUROSOILS), which had been certified for their adsorption coefficients for atrazine, 2,4-D and lindane (Certification of the European Reference Soil Set (IRMM-443-EUROSOILS)-Part I. Adsorption coefficients for atrazine, 2,4-D and lindane. Sci Total Environ, in press). The certification of these parameters was complemented by an additional certification of pH in suspension as well by the determination of indicative values for total nitrogen, organic and total carbon content. While Part I explained the principles of the value assignment process and discussed their application to the adsorption coefficients, Part II presents the certified values for pH as well as the indicative values for N , C and C . In addition, the assessment tot tot org of uncertainty components for stability and homogeneity, which have been included in the final uncertainty budget, is discussed.

The purpose of this work is to identify the powdered material contained in one of the tubes in order to confirm the hypothesis generated from ethnographical sources, that the rapd (snuf3') complex was associated with the consumption of Anadenanthera colubrina var. cebil, Fabaceae, the cebil, or, if not, which materials were inhaled. Following analysis with a light microscope, petrographic microscope and scanning electron microscope the unknown material was identified as cebil by comparison with reference material and specialized literature.

Domoic acid (DA) is a neurotoxic amino acid that is responsible for the human toxic syndrome, amnesic shellfish poisoning (ASP). A new rapid, sensitive liquid chromatographic (LC) method has been developed for the determination of DA in various marine samples. DA in marine biological materials was derivatised with 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F) and analysed using isocratic reversed-phase LC with fluorimetric detection. The calibration, based on standard DA 2 solutions, was linear in the range 0.04-2 mg / ml (r 50.998) and the detection limit (3:1, signal / noise) was better than 1 ng / ml. Using the certified reference material (MUS-1B), recoveries of DA from shellfish tissue were .95% (n55). When a strong anion exchange SPE cartridge was used for sample clean-up the detection limit was 6 ng DA / g mussel tissue. Good reproducibility was achieved with RSD values ranging from 3% for 8 mg DA/g (n55), to 5% for 0.04 mg DA/g (n55). This new method was successfully applied to the determination of DA in naturally contaminated shellfish and in marine phytoplankton cultures of Pseudonitzschia sp.

Laboratories have a strong, urgent need to assure the quality of their analytical results. Quality control (QC) is a key element in ensuring reliable results, because it requires both monitoring of the process and elimination of the causes of unsatisfactory performance. QC involves the use of blanks, certified reference materials (CRMs), duplicate samples, blind samples, and calibrating standards or spiked samples, among others. QC criteria are discussed for environmental monitoring of organic microcontaminants in water. In addition, quality criteria in the identification and confirmation of target analytes are considered.

In light of the renewed international interest in lunar exploration, including plans for setting up a permanent human outpost on the Moon, the need for next generation earth-based human space mission simulators has become inevitable and urgent. These simulators have been shown to be of great value for medical, physiological, psychological, biological and exobiological research, and for subsystem test and development, particularly closed-loop life support systems. The paper presents a summary of a survey of past, present and future human space mission simulators. In 2006, the Vienna based company Liquifer Systems Group (LSG) conducted an in-depth survey, for a European Space Agency (ESA) commissioned Phase-A contract involving a Design Study for a Facility for Integrated Planetary Exploration Simulation (FIPES). The survey data served as reference material for development of the FIPES architecture and, more importantly the application of the data ensured that the Systems Requirements reviewed and amended as part of the FIPES Study fully reflected the design, experience, and lessons learned from the use of such facilities. The paper addresses a hitherto unfulfilled need: a comprehensive, comparative survey of most, if not all, simulators to date. It is a condensed and updated version of the detailed ESA Technical Report produced for the FIPES Study. It presents a comparative analysis of simulator characteristics and consolidated summaries for each simulator classified into (1) site and purpose, (2) key technical data, (3) scientific and medical research functions, and (4) technology test and development functions. It is beyond the scope of this paper to provide details for all twenty-seven simulators surveyed. Therefore, the paper presents selected summaries of three sets of relatively recent simulation campaigns, one European, one American and the other Russian-International. The paper concludes with excerpts of lessons learned from these campaigns.

Imaging methods are applied in engineering and experimental mechanics areas to measure strain fields. The SPOTS project tackles the problem of traceability in optical strain measurement. Strain, being a displacement derivative, is a measurement quantity derived from the base unit length. We outline routes for traceability of optical strain measurement values, and underline the role of measurement standards for strain. Measurement uncertainty for calibration of an ESPI interferometer is detailed.

This report aims to determine the concentration of an unknown sample using the Beer’s Law plot of cobalt (II) nitrate. To achieve this objective, the following needed to be met: (1) to examine the essential components of a simple spectrophotometer, namely PerkinElmer Lambda 365 UV/Vis Spectrophotometer, (2) to determine the absorption spectrum of a solution, and (3) to prepare the Beer’s Law plot from the absorbance readings of known concentrations.

This work reports on x-ray absorption spectroscopy study at the Si K edge of several amorphous SiO x C y H z polymers prepared by plasma-enhanced chemical-vapor deposition with different C / O ratios. SiO 2 and SiC have been used as reference materials. The comparison of the experimental Si K-edge x-ray absorption nearedge structure spectra with theoretical computations based on multiple scattering theory has allowed us to monitor the modification of the local coordination around Si as a function of the overall C / O ratio in this kind of materials.

Radiochemical neutron activation analysis (RNAA) procedures for determination of Re at the ultratrace level based on use of liquid-liquid extraction (LLE) and extraction chromatography (EXC) have been developed. Two different LLE procedures were used depending on the way of sample decomposition using either 2-butanone or tetraphenylarsonium chloride in CHCl 3 . EXC employed new solid extractant materials prepared by incorporation of the liquid trioctyl-methylammonium chloride into an inert polyacrylonitrile matrix. The RNAA procedures presented have been compared and applied for Re determination in several biological and environmental reference materials.

Bowen's Kale) was determined using neutron activation analysis (NAA) in two different analytical modes: instrumental NAA with epithermal neutrons (ENAA), and NAA with radiochemical separation (RNAA). The ENAA mode was based on long-time 5-hour irradiation of samples in a special Cd lined box with counting after 8-month decay. The RNAA procedure consisted in 20-hour irradiation of samples, their decomposition/dissolution by alkaline-oxidative fusion, and precipitation of AgCl including several purification steps. Both methods provided Ag contents in the analyzed reference materials consistent with certified and/or literature values down to the ng . g -1 level.

Radiochemical neutron activation procedures using liquid-liquid extraction with tetraphenylarsonium chloride in chloroform from 1M HCl and solid extraction with ALIQUAT 336 incorporated in a polyacrylonitrile binding matrix from 0.1M HCl were developed for accurate determination of rhenium in biological and environmental samples at the sub-ng . g -1 level. Concentrations of Re in the range of 0.1 to 2.4 ng . g -1 were determined in several botanical reference materials (RM), while in a RM of road dust a value of ~10 ng . g -1 was found. Significantly elevated values of Re, up to 90 ng . g -1 were found in seaweed (brown algae). Results for Re in the brown algae Fucus vesiculosus in which elevated 99 Tc values had previously been determined suggested possible competition between Re and Tc in the accumulation process.

The concentration of boron was determined in twenty one geochemical reference materials (silicate rocks) by isotope dilution inductively coupled plasma‐mass spectrometry. Boron was extracted from the rocks using HF digestion, suppressing boron volatilisation through boron‐mannitol complexation. Sample solutions, in a diluted HCl matrix, were analysed by ICP‐MS without any separation of boron from the matrix elements. The results obtained were in agreement with the literature data and indicate that using the described procedure, trace amounts of boron can be very easily determined in complex matrices with rapidity and precision. With the instrumentation and reagents used in this study, this procedure can be used for the determination of 0.5 μg g−1 boron in a 15 0 mg silicate rock sample. Replicate analyses of the twenty one geochemical reference materials (GRM), ranging in boron concentration from 1.35 to 15 7 μg g−1, yielded precisions (relative standard deviation) varying between 0...

Resumo : Este trabalho tem como objetivo descrever e analisar a percepcao de professoras dos anos iniciais de escolaridade sobre o uso pedagogico de games no ensino de conceitos matematicos. Esta e uma pesquisa qualitativa. Foram realizadas entrevistas semiestruturadas com professoras de uma escola do interior do estado do Rio Grande do Sul. Concluimos que o uso da internet como fonte de informacao precisa ser mais discutido, utilizado e estudado pelos profissionais da educacao. Palavras Chaves : Games . Matematica. Professoras. Anos Iniciais.

An intercomparison exercise to determine the 14 C activity concentrations in a range of solid, environmental level materials was conducted between laboratories in the UK. IAEA reference materials, C2, C6 and C7, and an in-house laboratory QA material were dispatched in 2006 to ten laboratories comprising of members of the Analyst Informal Working Group (AIWG) and one other invited party. The laboratories performed the determinations using a number of techniques, and using the results each one was evaluated in terms of levels of precision, sensitivity and limits of detection. The results of the study show that all techniques are capable of successfully analysing 14 C in environmental level materials, however, a shortage of certified environmental reference materials exists. The suitability of the IAEA reference materials and other material for use as reference materials was also assessed.

As part of the Advanced Remediation Technologies (ART) Program, the Department of Energy (DOE) chose to demonstrate the capabilities of the THOR ® Steam Reforming process as a potential means to treat and prepare the Hanford Low Activity Waste (LAW) and Low Activity Waste Recycle (LAWR) waste steams for disposal. The Hanford LAW and LAWR waste streams will contain listed and characteristic hazardous waste constituents as well as underlying hazardous constituents that, under federal and state regulations, preclude the wastes from land disposal without treatment. An Engineering Scale Technology Demonstration (ESTD) utilizing the mineralization flowsheet of the THOR ® process was successfully completed in May 2008 at the Hazen Research facility in Golden, CO, using Hanford LAW and LAWR waste simulants. The Hanford LAW simulant composition was determined by DOE to represent the anticipated stream that would be processed by the Waste Treatment and Immobilization Plant (WTP) LAW melters. ...

A comprehensive micro‐Raman spectroscopic analysis of the Nakhla and Vaca Muerta meteorites is reported. The major and minor mineral components were identified from comparison with mineralogical standards and literature databases. The compositions of pyroxenes and olivines were obtained using only this technique and correlation data between band parameters and the chemical composition of reference materials existing in the literature. The presence of calcite in both meteorite specimens was noted; its identification inside eucrite grains in the Vaca Muerta meteorite is particularly noteworthy. Their spectral parameters show strong similarities. Aragonite associated with calcite is reported for the first time in Vaca Muerta meteorite. Spectra of siderite, which appears associated with clinopyroxenes, are also reported in Nakhla meteorite. Iron oxides were analysed in detail in both meteorites. Magnetite is the main oxide phase observed in Nakhla and goethite, lepidocrocite and magneti...

An inductively coupled plasma isotope dilution mass spectrometric (ICP-IDMS) method was developed as a suitable method -with respect to its sensitivity, precision, accuracy, and time-consumption -for the analysis of toxic heavy metal traces (Pb, Cd, Cr, and Hg) in polyolefins. Results for Pb, Cd, and Cr were compared with those obtained by thermal ionization isotope dilution mass spectrometry (TI-IDMS), which was used as a reference method. Because of its high first ionization potential and its high volatility mercury could not be determined by TI-IDMS. A multi-element spike solution, containing isotopically enriched 206 Pb, 116 Cd, 53 Cr, and 201 Hg, was used for the isotope dilution step. Decomposition of the polyolefin samples was carried out with concentrated HNO 3 at temperatures of about 300 °C in a high pressure asher (HPA). This procedure decomposes polyolefins completely and allows isotopic equilibration between sample and spike isotopes. Detection limits of 16 ng/g, 5 ng/g, 164 ng/g, and 9 ng/g were obtained for Pb, Cd, Cr, and Hg by ICP-IDMS using only sample weights of 0.25 g. In different commercially available polyethylene samples heavy metal concentrations in the range of < 5 ng/g to 4 × 10 3 ng/g were analyzed. Both mass spectrometric methods were applied within the EU project "Polymeric Elemental Reference Material (PERM)" for the certification of two polyethylene reference materials. The ICP-IDMS results agreed very well with those of TI-IDMS which demonstrates the accuracy of the ICP-IDMS method also suitable for routine analyses.

The method describes the determination of phosphorus in copper artifacts by graphite furnace AAS using La(NO 3 ) 3 as the matrix modifier. The sensitivity of the procedure is calculated as 3500 pg (pico grams). The accuracy of the method was assessed by analyzing two MBH copper alloys. The results obtained are in good agreement with the certified values. Phosphorus, up to 0.006% in 25-mg samples taken from six copper coins, was successfully determined.

Consistency of δ 13 C measurements can be improved 39-47% by anchoring the δ 13 C scale with two isotopic reference materials differing substantially in 13 C/ 12 C. It is recommended that δ 13 C values of both organic and inorganic materials be measured and expressed relative to VPDB (Vienna Peedee belemnite) on a scale normalized by assigning consensus values of -46.6‰ to L-SVEC lithium carbonate and +1.95‰ to NBS 19 calcium carbonate. Uncertainties of other reference material values on this scale are improved by factors up to two or more, and the values of some have been notably shifted: the δ 13 C of NBS 22 oil is -30.03‰. Differences in measured isotope amount ratios of stable carbon isotopes ( 13 C/ 12 C), commonly called δ 13 C values, are used in oceanography, atmospheric sciences, biology, paleoclimatology, geology, environmental sciences, food and drug authentication, and forensic applications. Progress in these fields requires smaller measurement uncertainties to be achieved. Advances require more accurate and intercomparable measurements; for example, a difference of 0.01‰ in δ 13 C of global atmospheric CO 2 can equate to a global carbon balance source/sink discrepancy of ∼400 Tg among international monitoring networks. 1 Although advances in instrumentation enable increasingly precise measurements, laboratories measuring the same specimen often disagree by 10 times their reported "uncertainty" of measurement, 2,3 and agreement has not improved appreciably in the last two decades, except in special cases.

Seawater was sampled from different depths in the North Atlantic Ocean (Canary Islands region) and distributed among three different labs for the determination of titration alkalinity. Analysis was performed by potentiometric methods, involving titration in a closed cell, titration in an open cell and a two end-point acid addition method. The precision, which is the sample reproducibility taken from the mean standard deviation for replicate measurements, was between 0.45 and 0.90 µmol · kg–1 for the individual labs. Accuracy, here taken as the deviation for the values of a lab from the mean of all three, was mostly below 1 µmol · kg–1 and never exceeded 0.1% of the sample value. Mean standard deviation for all labs and all samples was 0.87 µmol · kg–1, once the individual methods were calibrated using certified reference material (CRM). Without CRM calibration, the mean standard deviation would increase to 2.8 µmol · kg–1. The conclusion is that current high precision methods for al...

The sorption behaviour of carbon nanotubes (CNTs) toward some divalent metal ions such as Cu(II), Co(II), Ni(II), Zn(II), Pb(II), Mn(II) and Cd(II) has been investigated systematically. The affinity order of the metal ions towards CNTs at pH in the range of 7.0-9.0 was: Cu(II) N Pb(II) N Zn(II) N Co(II) N Ni(II) N Cd(II) N Mn(II). The experimental parameters for preconcentration of copper, which exhibits the highest affinity towards carbon nanotubes, on a microcolumn packed with CNTs prior to its determination by flame atomic absorption spectrometry have been investigated. Copper can be quantitatively retained at pH 8.2 from sample volume up to 150 mL and then eluted completely with 0.1 mol L -1 HNO 3 . The limit of detection limit for Cu(II) determination with FAAS detection was 2.1 μg L -1 , and the RSD was 3.5% at the 50 μg L -1 level. Under the optimal conditions for copper enrichment also Zn(II), Pb(II) and Ni(II) could be quantitatively preconcentrated from water samples. The method was validated using a certified reference materials BCR-610 and SRM 1640.

The concept of liquid coacervate extraction (LCE) is deployed to accomplish metal speciation after appropriate derivatization of the target metallic species. The method involves the partitioning of the hydrophobic metal chelates, produced from the reaction of Cr with APDC, in the vesicular aggregates formed from an anionic surfactant with alkaline earth metals and a cosurfactant, which are separated from the bulk aqueous phase. Under the established experimental conditions, the method offers high reproducibility, very low detection limits and recoveries in the range of 95 -104%. Moreover, the method affords high tolerance for EDTA, which is used as a masking agent in order to avoid interferences from co-extracted metals. Validation of the outlined method was performed by analysing a certified reference material (BCR 544) yielding recoveries higher than 94% for both Cr oxidation states.

The near-term objective of the work reported here is to develop a protocol for rapidly mapping critical-dimension (CD) and edge roughness from high-resolution Scanning-Electron Microscopy (SEM) images of reference-material features patterned on Single-Crystal CD Reference Material (SCCDRM) chips. The longer term mission is to formulate a metric to enable automated characterization of as-fabricated reference-feature segments for rapid identification of fabrication-process enhancements and, ultimately, to select feature segments for further characterization as standard referencematerials. The selection of results presented here provides a new level of SCCDRM characterization showing that segments of some SCCDRM features appear to have very useful extended lengths of up to 200 nm of superior CD uniformity.

In this article the role of reference materials is confined to chemical measurements only. Recognized reference materials are one of the tools to obtain comparability of analytical results. Recognition demands confidence in the reference materials and in the reference material producers. A reference material producer is a technical competent body that is fully responsible for the certified or other property values of the reference material. The "analyte" has to be specified in relation to the selectivity of analytical procedure. The full range of reference materials can be presented as a three-dimensional space of the coordinates: analyte,

The present study aims to optimize the extraction of phenolics by microwaveassisted extraction (MAE) using the response surface methodology (RSM), from Lemon verbena leaves. The optimized extract was tested for its antioxidant activity using two methods (DPPH and reducing power) and its antibacterial efficiency by using disk diffusion assay and broth microdilution, against two Gram-negative (Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853) and two Gram-positive (Staphylococcus aureus ATCC 25923, Bacillus subtilis ATCC 6633) strains. Under the optimized conditions (40% (v/v): of ethanol concentration, 188 s of irradiation time, 600 W of microwave power and 1:40 g/mL of solid-to-liquid ratio) the total phenolic content (TPC) was 67.87±1.61 mg GAE/g DW. The IC50 of the extract was 139.65±1.44 µg/mL and 56.60±2.79 µg/mL for DPPH inhibition and reducing power, respectively. The best antibacterial activity was shown by the extract obtained by MAE with lower MBC (1.56 to 18.75 mg/mL) and MBC/MIC ratio. Lemon verbena extract can be used as an ingredient in cosmetics, food supplements and herbal medicinal products due to its interesting biological properties.

A fast microwave assisted extraction procedure was developed and optimized for their eventual exploitation in the three-stage sequential extraction procedure proposed by modified BCR protocol (the community Bureau of Reference now the European Union "Measurement and Testing Programme"). The effects of the microwave treatment on the extraction of Cd, Cr, Cu, Ni, Pb and Zn from untreated sewage sludge collected from Hyderabad city (Pakistan) were compared with those obtained from sequential BCR extraction procedure. In sequential BCR method, each extraction step takes 16 h, where as with the use of compromised microwave conditions, extraction steps could be completed in about 120 s, for each step, respectively. Extractable Cd, Cr, Pb and Ni obtained by both comparable methodologies were measured by electrothermal atomic absorption spectrometry (ETAAS), while for Cu and Zn flame atomic absorption spectrometry (FAAS) was used. The validations of both extraction techniques were compared by the analysis of certified reference material of soil amended with sewage sludge (BCR 483). The results of the partitioning study of untreated waste water sewage sludge, indicate that more easily mobilized forms (step 1) were predominant for Cd, Ni and Zn (28.3, 28.4 and 43.7%), in contrast, the largest amount of Cd and Pb (66.4 and 72.8%) was associated with the iron/manganese oxide while Cr and Ni (71.2 and 38.7%) in organic matter/sulphide fractions. The overall metal recoveries in steps 1-3 (excluding residual step) were 95.3-104% of those obtained with the sequential BCR protocol. The accuracy of the proposed microwave extraction method (expressed as %R.S.D.) was lower than 10% for all metals.

The arsenic (As) contaminated sediment serves as a long-term source of arsenic because its mobility and transport in the environment are strongly influenced to associated solid phase. A single extraction method based on the reagents employed in the BCR three steps sequential extraction scheme (BCR-SES) for partitioning of arsenic (As) in sediment samples has been developed. The single-step extraction enabled a reduction of extraction times, yielding extractable contents in accordance with those obtained by application of the BCR-SES, which can be regarded as a standard method and validated by using certified reference material BCR 701. The extractable As content associated with different phases in sediment samples were analysed by electrothermal atomic absorption spectrophotometer. The extraction efficiency of As by single-step extraction was slightly higher than BCR-SES, ranged (100-104%), while difference was not significant at 95% confidence limit with <10% precision. The sediment samples from different origins varied in their physico-chemical properties and total As content. The relative mobility of As obtained from different origins was found in increasing order as: acid soluble fraction < oxidizable fraction < reducible fraction. The acid soluble fraction of As was higher in lake sediment samples as compared to those of canal and river sediments, indicating the contamination of lake ecosystem.

The aim of the study was to evaluate total arsenic (As) in five tissues (gills, mouthpiece, intestine, liver and muscles) of 10 fish species caught from As contaminated Manchar Lake (26°3 0 N: 67°6 0 E) Sindh Pakistan during 2006-2007. The total As concentration was determined by hydride generation atomic absorption spectrometry (HG-AAS), prior to microwave assisted acid digestion. The certified reference material DORM-2 (dogfish muscle) was used to check the quality control of the technique. The good agreement with the certified value at 95% confidence limit confirmed the validity of As determination method. The limit of detection (LOD) and limit of quantitation (LOQ) of As were 0.034 and 0.11 lg/g, respectively. The As concentration ranges in different tissues were obtained as: gills (1.01-10.4), mouth pieces (1.01-18.6), intestine (1.01-11.2), liver (3.51-10.9) and in muscles (2.12-15.2) lg/g on dried basis. The bioaccumulation factor (BAF) for As in fish muscles were found in two ranges (4.88-7.2) and (17.6-35.3). The contribution of the daily intake of As, based on the consumption of 250 g fresh fish muscles per day was found in the range of 0.1-0.76 lg, higher than WHO tolerable limit.

Objective There is accumulating facts that the metabolism of essential trace elements is altered in diabetic patients. The aim of present study was to compare the status of essential trace elements, chromium (Cr), manganese (Mn), and zinc (Zn) in biological samples (whole blood, urine and scalp hair) of insulin dependent diabetic mothers (age ranged 30-40) and their newly born infants (n = 76). An age matched 68 non-diabetic mothers and their infants, residing in the same locality, were selected as referents. For a comparative study, the biological samples of non-diabetic and diabetic pregnant and non pregnant of same age group and socio-economics status were also analysed. Methodology The biological samples (scalp hair, blood and urine) were collected from study and referent groups. The Cr, Mn and Zn concentrations in all three biological samples were determined by a flame/electrothermal atomic absorption spectrometer, prior to microwave assisted acid digestion. The validity and accuracy of the methodology was checked by certified reference materials (CRMs) and using conventional wet acid digestion method on same CRMs. The mean values of Cr, Mn and Zn in scalp hair and blood samples of diabetic mothers and their infants were significantly lower as compared to the referent mothers-infants pairs (p \ 0.01), while urinary excretion of all these elements were high in diabetic mother-infant pair samples. Conclusion The deficiencies of essential trace elements, Cr, Mn and Zn in biological samples of diabetic women, may play role in the pathogenesis of diabetes mellitus and impacts on their neonates.

In Europe one feature of National Food Composition Databanks (nFCDBs) is to provide data soundly supported in standardized quality assurance procedures. It is now widely recognized that the evaluation of the degree of dispersion associated with a result is an ...

A new method has been developed for the determination of Tl(I) based on simultaneous sorption and preconcentration with a microcolumn packed with TiO 2 nanoparticle with a high specific surface area prepared by Sonochemical synthesis prior to its determination by graphite furnace atomic absorption spectrometry (GFAAS). The optimum experimental parameters for preconcentration of thallium, such as elution condition, pH, and sample volume and flow rate have been investigated. Tl(I) can be quantitatively retained by TiO 2 nanoparticles at pH 9.0, then eluted completely with 1.0 mol L À1 HCl. The adsorption capacity of TiO 2 nanoparticles for Tl(I) was found to be 25 mg g À1 . Also detection limit, precision (RSD, n = 8) and enrichment factor for Tl(I) were 87 ng L À1 , 6.4% and 100, respectively. The method has been applied for the determination of trace amounts of Tl(I) in some environmental water samples with satisfactory results.

High accuracy procedures for the determination of arsenic are needed for assigning reference values to certified reference materials (CRMs). There are a number of problems associated with the determination of total arsenic by inductively coupled plasma-mass spectrometry. Arsenobetaine (AsB) (the major species in fish) gives an enhanced response (9%) when compared to inorganic arsenic(V) and is very difficult to decompose. Chloride causes interference at m/z 75 by the formation of ArCl + and chloride levels can be significant in marine fish. Also residual carbon in digests can lead to enhancement of arsenic signals by charge transfer effects. This can easily lead to erroneous quantification when compared to standards that do not contain carbon. This newly developed procedure overcomes these issues by complete mineralisation of the matrix leaving insignificant amounts of residual carbon and by removal of chlorine by evaporation. A detection limit of 30 ng/g was achieved. Recoveries for the following CRMs: DORM 2 100.1 ± 4.3%, SRM1548 96.1 ± 4.6%, BCR 422 103.6 ± 6.2% and SRM2976 105.9 ± 6.2% were obtained. The digestion procedure uses open vessel wet digestion with a mixture of sulfuric and nitric acid held at 300°C. The decomposition of AsB was confirmed by speciation analysis of the digest. Carbon (m/z 13) was monitored to demonstrate the efficiency of the digestion. Instrumentation for the reduction of ArCl + interference was not required and this view is supported by the recovery data. Measurements were performed by external calibration using tellurium as an internal standard.

Results of an international intercomparison study (CCQM-P86) to assess the analytical capabilities of national metrology institutes (NMIs) and selected expert laboratories worldwide to accurately quantitate the mass fraction of selenomethionine (SeMet) and total Se in pharmaceutical tablets of selenised-yeast supplements (produced by Pharma Nord, Denmark) are presented.

A comparison of high accuracy methods for the analysis of total sulfur in gas oils by three metrology institutes is described. The work contains a comparison of three different aspects of the analysis: sample digestion, instrumental measurement and isotope dilution strategies. Thermal ionisation mass spectrometry (TIMS) in combination with high pressure asher (HPA) or Carius tube digestion has traditionally been used for such high accuracy analysis. However, this paper demonstrates that the faster, less laborious technique of ICP-MS in combination with microwave digestion is equally capable. Results from the comparison experiments show excellent agreement for fuel samples containing sulfur concentrations in the range 11-200 g g -1 . This excellent agreement across the different sample preparation, measurement and isotope dilution techniques has been exploited in the certification of two new diesel fuel reference materials.

A new method for the electrothermal atomic absorption spectrometric determination of vanadium in milk and infant formulas using suspensions to avoid the need for previous dissolution of samples is described. Sensitivity is improved by a procedure based on preconcentration and removal of the matrix, using ionexchange (Dowex 1X8-100). Suspensions of 15% (m/v) infant formula samples were prepared in a medium containing 0.05 M sodium citrate (pH 7.2) and passed through the ion exchange column. Vanadium was eluted from the column using 1 M hydrochloric acid and injected in the graphite furnace using a mixture of hydrofluoric acid plus magnesium nitrate as chemical modifiers. Calibration was carried out using multiple injection and aqueous standards prepared in the same medium. Detection limits were 0.2 ng g -1 for infant formulas and 0.02 g L -1 for cow milk samples. The reliability of the procedure was checked by comparing the results obtained with those found using a previous mineralization stage and by analyzing five certified reference materials.

An electrothermal atomic absorption spectrometric procedure for zinc determination in animal tissues is Wrst optimized and then used to measure the metal content of diVerent tissues from normal and dystrophic mice. The procedure involves minimal manipulation of the sample to overcome the severe contamination problems normally associated with the measurement of low zinc levels. The samples (recommended amount 10 mg) are slurried in 2 ml of a 10-mM tetramethylammonium hydroxide solution containing 0.1 g/100 ml silicone antifoam. After mild heating at 60 °C for 10 min and homogenization for 1 min, the suspensions are submitted to a 10-fold dilution and then injected into the electrothermal atomizer. Calibration is carried out using aqueous standard solutions of zinc prepared in the same suspension media. The reliability of the whole procedure is veriWed using three certiWed reference materials.

We present new analytical data of major and trace elements for the geological MPI‐DING glasses KL2‐G, ML3B‐G, StHs6/80‐G, GOR128‐G, GOR132‐G, BM90/21‐G, T1‐G, and ATHO‐G. Different analytical methods were used to obtain a large spectrum of major and trace element data, in particular, EPMA, SIMS, LA‐ICPMS, and isotope dilution by TIMS and ICPMS. Altogether, more than 60 qualified geochemical laboratories worldwide contributed to the analyses, allowing us to present new reference and information values and their uncertainties (at 95% confidence level) for up to 74 elements. We complied with the recommendations for the certification of geological reference materials by the International Association of Geoanalysts (IAG). The reference values were derived from the results of 16 independent techniques, including definitive (isotope dilution) and comparative bulk (e.g., INAA, ICPMS, SSMS) and microanalytical (e.g., LA‐ICPMS, SIMS, EPMA) methods. Agreement between two or more independent me...