Need For Specific Standards Research Articles

Sensitive Detection and Quantification of Oxygenated Compounds in Complex Samples Using GC-Combustion-MS.

This work introduces a new element-selective gas chromatography detector for the accurate quantification of traces of volatile oxygen-containing compounds in complex samples without the need for specific standards. The key to this approach is the use of oxygen highly enriched in 18O as the oxidizing gas in a combustion unit (800 °C) that allows us to directly and unambiguously detect the natural oxygen present in the GC-separated compounds through its incorporation into the volatile species formed after their combustion and their subsequent degradation to 16O in the ion source. The unspecific signal due to the low 16O abundance in the oxidizing gas could be compensated by measuring the m/z 12 that comes as well from the CO2 degradation. Equimolarity was proved with several O-containing compounds with different sizes and functionalities. A detection limit of 28 pg of injected O was achieved, which is the lowest ever reported for any GC detector, which barely worsened to 55 and 214 pg of O when the oxygenate partially or completely coeluted with a very abundant matrix compound. Validation was attained by the analysis of a SRM to obtain accurate (99-103%) and precise (1-4% RSD) results. Robustness was tested after spiking a hydrotreated diesel with 10 O-compounds at the ppm level, which could be discriminated from the matrix crowd and quantified (mean recovery of 102 ± 9%) with a single generic standard. Finally, it was also successfully applied to easily spot and quantify the 33 oxygenates naturally present in a complex wood bio-oil sample.

Professional Standards and Recognition for UK Personal Tutoring and Advising

The Higher Education and Research Act established both a regulatory framework and the Teaching Excellence Framework with associated metrics for student retention, progression and employability in the UK. As a key site in meeting these requirements, the significance of personal tutoring is clear. Despite this, according to existing institutional research, there is a need for developmental support, greater clarification on the requisite competencies, and adequate recognition for those undertaking this challenging role. Moreover, arguably compounding these concerns is the lack of distinct professional standards for personal tutoring and advising against which to measure effective practice, only recently addressed by the publication of The UKAT Professional Framework for Advising and Tutoring. Through a review of the literature supported by findings from a survey of practitioners, this paper discusses the need for such standards, and the skills and competencies populating them. Additionally, the usefulness of pre-existing standards pertinent to tutoring work (such as the UK Professional Standards Framework for Teaching and Supporting Learning in HE) are evaluated and the value and recognition with which personal tutoring standards could be associated are advanced. The survey supported the need for specific standards – represented by the UKAT framework - as evident from the literature. Justifications provided for both this and the opposing view are examined. Clarity for both individual practitioners and institutions was stipulated along with meaningful recognition and reward for this work which is considered highly important and yet ‘invisible’. The participants and literature reviewed identify relevant content along with illuminating the debate about the relationships between personal tutoring, teaching and professional advising roles. Valuable analysis of standards, recognition and reward also emerged. This is considered by discussing the connection between standards and changes to practice, responses to policy developments and the purpose of ‘standards’ in comparison to ‘guidance’. The paper proposes that the recent introduction and use of a bespoke framework is a necessary response to alleviate some of the current tensions which beset personal tutoring and advising in higher education.

Phonological awareness and early reading and writing abilities in early childhood education: preliminary normative data

ABSTRACT Objective: to provide preliminary normative data for the Reading and Writing Test by type of school, and normative data for the Phonological Awareness Test by Oral Production for private schools and update their normative data available for public schools, all of which are for children in the final year of early childhood education. Methods: 267 children, in the age range of 5 years, and typical development. Identification Questionnaire for Parents, Phonological Awareness Test by Oral Production and Reading and Writing Test were used. The means of performance in the tests of the present sample were compared with the existing normative data to justify normative data provision and updating. Results: Student’s t-test revealed that the private school children outperformed those of the public schools in all measures, reinforcing the need for specific standards, according to the type of school. There were strong to very strong relationships among the variables evaluated, demonstrating a marked association between phonological awareness and initial reading and writing abilities. The Wilcoxon test revealed significant differences between the performance of the children of the present study, from both private and public schools, and the data from the Phonological Awareness Test by Oral Production standardization sample, suggesting the need to update the Phonological Awareness Test by Oral Production standards. Finally, the new normative data were presented. Conclusion: the need to make available and update the test standards used, according to the type of school, was confirmed. Further studies are necessary to expand the data presented to other age groups.

Elemental Mass Spectrometry for Absolute Intact Protein Quantification without Protein-Specific Standards: Application to Snake Venomics.

Absolute protein quantification methods based on molecular mass spectrometry usually require stable isotope-labeled analogous standards for each target protein or peptide under study, which in turn must be certified using natural standards. In this work, we report a direct and accurate methodology based on capLC-ICP-QQQ and online isotope dilution analysis for the absolute and sensitive quantification of intact proteins. The combination of the postcolumn addition of 34S and a generic S-containing internal standard spiked to the sample provides full compound independent detector response and thus protein quantification without the need for specific standards. Quantitative recoveries, using a chromatographic core-shell C4 column for the various protein species assayed were obtained (96-100%). Thus, the proposed strategy enables the accurate quantification of proteins even if no specific standards are available for them. In addition, to the best of our knowledge, we obtained the lowest detection limits reported in the quantitative analysis of intact proteins by direct measurement of sulfur with ICPMS (358 fmol) and protein (ranging from 7 to 15 fmol depending on the assayed protein). The quantitative results for individual and simple mixtures of model proteins were statistically indistinguishable from the manufacturer's values. Finally, the suitability of the strategy for real sample analysis (including quantitative protein recovery from the column) was illustrated for the individual absolute quantification of the proteins and whole protein content in a venom sample. Parallel capLC-ESI-QTOF analysis was employed to identify the proteins, a prerequisite to translate the mass of quantified S for each chromatographic peak into individual protein mass.

Liquid Chromatography, Chemical Oxidation, and Online Carbon Isotope Dilution Mass Spectrometry as a Universal Quantification System for Nonvolatile Organic Compounds

A procedure for the universal detection and quantification of polar organic compounds separated by liquid chromatography (LC) based on postcolumn carbon isotope dilution mass spectrometry (IDMS) was developed. The eluent from the LC column is mixed online with a continuous flow of (13)C-enriched sodium bicarbonate, and the sodium persulfate oxidation reaction in acidic media is employed to achieve isotope equilibration. All carbon-containing compounds eluting from the column are oxidized to (12)CO(2) and (13)CO(2), respectively, and the carbon dioxide is separated from the aqueous phase using a gas-permeable membrane. The gaseous carbon dioxide is then carried to the mass spectrometer for isotope ratio measurements. Different water-soluble organic compounds were evaluated using a flow injection configuration to assess the efficiency of the oxidation process. Most water-soluble organic compounds tested showed quantitative oxidation. However, chemical structures involving conjugated C═N double bounds and guanidinium-like structures were found to be resistant to the oxidation and were further studied. For this purpose, (13)C(1)-labeled creatine (with the isotopic label in the guanidinium group) was employed as model compound. Specific conditions for the quantitative oxidation of these compounds required lower flow rates and the addition of metallic catalysts. This novel approach was tested as a universal detection and quantification system for LC. A simple standard mixture of four amino acids was separated under 100% aqueous conditions and quantified without the need for specific standards with good accuracy and precision using potassium hydrogen phthalate as internal standard. The main field of application of the developed method is for the purity assessment of organic standards with direct traceability to the International System of Units (SI).

Towards compound-independent calibration for organic compounds using online isotope dilution mass spectrometry

Isotope dilution mass spectrometry (IDMS) can be considered a primary measurement method directly traceable to the International System of Units (SI). This measurement technique is increasingly employed in routine laboratories, owing to its unequalled analytical performance, precision and ease of accreditation. Unfortunately, for the adequate application of IDMS, several isotopically labelled standards, corresponding to the compounds of interest, are required. Additionally, when the enriched isotope is continuously added after a chromatographic separation, and an elemental ion source is used, it allows quantification of the different analytes being eluted from the column without requiring specific standards for each compound (online IDMS). In this article, we discuss how the traditional applicability of online IDMS for elemental speciation can be dramatically expanded by using carbon isotope tracers, oxidation or combustion reactions and a conventional molecular ion source. With such a strategy every carbon-containing compound being eluted from a chromatography system can be quantified without the need for specific standards as long as quantitative combustion/oxidation and complete elution occur. So far, only gas chromatography-combustion-mass spectrometry applications have been described, but recent results indicate the great possibilities of extending this novel approach to the quantification of organic compounds after separation by liquid chromatography.

A re-evaluation of two key reagents for in vivo studies of Wnt signaling

Conditional mutations and transcription-based reporters are important new tools for exploring the dynamic functions of biological pathways in vivo. While studying the role of the Wnt signaling pathway in cartilage, we observed that the β-catenin-dependent reporter TOPGAL was expressed in chondrocytes in which β-catenin was conditionally inactivated using a Col2a1::cre driver. Here we show that in these embryos recombination is complete and full-length β-catenin protein is absent in chondrocytes. Although a null allele in this context, the recombined β-catenin locus produces a stable transcript that encodes a truncated protein. The truncated protein alone fails to activate TOPFLASH, but strongly potentiates reporter activity in the presence of expressed β-catenin or Tcf4. Together, these data show that each mouse model exhibits specific undesirable properties, findings that strongly suggest the need for specific standards to ensure proper validation of this new generation of genetic tools.

A re-evaluation of two key reagents for in vivo studies of Wnt signaling

Conditional mutations and transcription-based reporters are important new tools for exploring the dynamic functions of biological pathways in vivo. While studying the role of the Wnt signaling pathway in cartilage, we observed that the β-catenin-dependent reporter TOPGAL was expressed in chondrocytes in which β-catenin was conditionally inactivated using a Col2a1::cre driver. Here we show that in these embryos recombination is complete and full-length β-catenin protein is absent in chondrocytes. Although a null allele in this context, the recombined β-catenin locus produces a stable transcript that encodes a truncated protein. The truncated protein alone fails to activate TOPFLASH, but strongly potentiates reporter activity in the presence of expressed β-catenin or Tcf4. Together, these data show that each mouse model exhibits specific undesirable properties, findings that strongly suggest the need for specific standards to ensure proper validation of this new generation of genetic tools. Developmental Dynamics 240:2060–2068, 2011. © 2011 Wiley-Liss, Inc.

Mesiodistal sizes and intermaxillary tooth-size ratios of two populations; Spanish and Peruvian. A comparative study

Adequate tooth-size ratios are required to ensure the satisfactory outcome of orthodontic treatment. Consequently, various methods of measuring tooth-size ratios have been developed being the Bolton ratio the most commonly accepted, known and used one. This ratio depending directly on mesiodistal tooth size has been associated with different ethnic backgrounds. Some authors suggest the need for specific standards for every population. The objectives of our study were; to measure and to compare mesiodistal tooth sizes and the Anterior and Overall Bolton ratios in two different populations, one Peruvian and the other Spanish with the same digital method. The sample included 149 individuals composed of two groups; 99 Spanish (mean age 14.19), 65 being females and 34 males and 50 Peruvian (mean age 14.46), 18 being males and 32 females. The mesiodistal sizes of each of the patients were measured using a digital method and the Anterior and Overall Bolton ratios were calculated. Tooth size does indeed involve a strong ethnic component, and the Anterior Bolton ratio is specific for each ethnic group. The conclusions are; tooth sizes of the Peruvian population were greater than those of the Spanish population. The Anterior Bolton ratio of Peruvian individuals was greater than that of the Spanish, whereas no differences were found for Overall Bolton ratio. These differences suggest the need for specific standards for the Spanish and Peruvian population.

A Quantitative Universal Detection System for Organic Compounds in Gas Chromatography with Isotopically Enriched 13CO2

Cheap and cheerful: Postcolumn carbon-isotope dilution with (13)CO(2) in combination with the coupling of gas chromatography, combustion, and EIMS (valve in position B in the picture) provides a generic quantitative approach for every organic compound without the need for specific standards. A GC-MS instrument can be upgraded by a simple low-cost modification without any loss of the structural information provided by electron ionization sources.

The Encoded Archival Guide (EAG) DTD and the Censo-Guía de los Archivos de España e Iberoamérica Project: An Electronic Guide to Spanish and Iberian American Archives

SUMMARY This paper argues that there is a need for specific standards for the description of archive repositories. With this objective in mind a DTD has been created, called Encoded Archival Guide (EAG) that provides an electronic format for the storage, publication and exchange of information related to archive repositories. The different elements and attributes that make up the EAG DTD are described, as well as their application to the Electronic Guide to Spanish and Iberian American Archives that includes information about more than 42,000 institutions.

Preventing Asthma through Housing Interventions: How Supportive is the US Policy Environment?

This paper investigates whether the policy environment in the United States is supportive of addressing the asthma epidemic through housing plans and policies. Asthma is increasing at an alarming rate worldwide and is linked to allergens in the housing environment such as ground-level ozone, excessive moisture and dust, rodents and pests, and environmental tobacco smoke. The study finds basic laws and regulations are in place regulating outdoor air quality and calling for the maintenance of public and rental housing in good condition, but there is still a need for specific standards to be adopted into law, for better enforcement of existing laws, and for increased funding. Because asthma prevention programs are relatively new, the paper reviews the US experience with lead-based paint hazard control programs to identify the components of effective strategies. These include explicit health objectives in housing plans and policies, promotion by both health and housing officials, advocacy by citizens' groups and tenants' associations, adequate funding for implementation, and focus on multiple health outcomes.

SIMS ionization of hydrogen in silicates: a case study of kornerupine

H/Si ionization in kornerupine, an (Mg, Al)-rich silicate mineral, has been investigated. There are significant variations (about 30% rel.) in the relative-to-Si ion yield for H [IY(H/Si)] as a function of chemical composition of the matrix kornerupine: ∼38–45 wt% Al2O3, ∼29–32 wt% SiO2, ∼15–20 wt% MgO, ∼0–11 wt% FeOtot, ∼2–4 wt% B2O3 and minor variations for the remaining components. There are strong correlations between IY(H/Si) and (Fe + Mn)(at) [where (at) represents the cation abundance in the sample (by atoms)] (r2 = 0.80); for Mg and Al(at), r2 = 0.73 and 0.90, respectively. The absolute ion yield for H [IY(H)] is strongly correlated with (Fe + Mn)- and Si(at) (r2 = 0.92 and 0.94, respectively). It is possible to make adequate corrections to IY(H/Si) as a function of sample composition to obtain accurate H2O (wt%) concentrations, reducing (if not overcoming) the need for specific standards (in most cases unavailable) that match the chemical composition of the sample. A model is proposed for H ionization in this matrix. The present outcome is qualitatively similar to the results obtained for other silicates (schorl, foitite, dravite, axinite, amphibole) and represents a valid basis for modelling SIMS ionization of H in silicates.

Review of international standards for grid connected photovoltaic systems

Photovoltaic power systems are unique in their characteristics and in their mode of application to buildings. Grid connected PV is being applied in a variety of applications including large centralised stations, commercial buildings and individual houses. There is a need for specific standards to address distinctive new issues created by grid connected PV power systems. Internationally many countries are attempting to develop standards for building integration, DC side issues and grid connection issues. This paper surveys the current developmental state of the major countries’ standards in this area, comparing and contrasting, standards and guidelines under development.

Determination of metallic impurities in a‐Si:H by SIMS

AbstractSecondary ion mass spectrometry (SIMS) has been employed to characterize the metallic impurities introduced into ion beam deposited a‐Si: H. For quantitative results, this type of characterization normally requires a specific standard for each element of interest. Ion implantation has been the method of choice for providing these types of standards in Si. The problem with this approach is the time and cost required in obtaining implants for each element to be analyzed. In this study, we describe the application of the local thermal equilibrium (LTE) model of SIMS quantitation to the analysis of metallic impurities in an a‐Si: H matrix. This method circumvents the need for specific standards for each element. Our results indicate that useful quantitative data can be obtained using the LTE method calibrated with one boron implant into c‐Si wafer.