The implementation of accreditation in a chemical laboratory

This article describes the current state of the art in the accreditation of chemical laboratories, both in Europe and world-wide, emphasising the most common discussion topics. The results of recent proficiency testing in chemical laboratories are summarised to draw conclusions on the performance of accredited laboratories.     

Step-by-step implementation of a quality system in the laboratory

In recent years laboratories have undergone huge transformations due to the technological development of inspection and testing equipment; the introduction of computerised and automated systems; keen competitiveness between companies/laboratories as a result of demand within Europe and on the international market; and greater consumer awareness of the quality of the products available. Laboratory accreditation, though a voluntary process, is formal recognition by an accreditation body of the laboratory's competence to carry out certain tests. This article presents those aspects which should be taken into account in the step-by-step implementation of a quality system and also makes reference to the requirements for the operation of accredited laboratories in accordance with European Standard EN 45001.     

Implementation of ISO/IEC 17025 standard in a nuclear analytical laboratory: The KAERI experience

The practical experience on the implementation of ISO/IEC 17025 compliant quality system in a nuclear analytical laboratory of the Korea Atomic Energy Research Institute (KAERI) is described. This paper summarizes the need for a quality system and accreditation, the process of a quality system implementation, the quality system structures, and the formal accreditation of our laboratory by the Korean Laboratory Accreditation Scheme (KOLAS). Also, the improvements in the management, technical and service quality which resulted from implementation of this system are briefly reported.     

The effect of water‐mediated catalysis on the intramolecular proton‐transfer reactions of the isomers of 5‐chlorouracil: a theoretical study

The geometrical structures and thermal energies (E), enthalpies (H) and Gibbs free energies (G) of 13 isomers of 5‐chlorouracil (5ClU) in the gas and water phases were investigated using the density functional theory (DFT) method at the M06‐2X/6‐311++g(3df,3pd) level. The isomers of 5ClU can be microhydrated at different molecular target sites. The mono‐ and dihydrated forms are the most stable in both the gas and water phases, and, because of the intermolecular interactions, the hydrations lead to a degree of change in the stability trend. Two types of isomerizations were considered: the internal H—O bond rotations in which the H atom rotates 180° around the C—O bond and the intramolecular proton‐transfer reactions in which an H atom is transferred between an O atom and a neighbouring N atom. The forward and backward energy barriers for isomerizations of nonhydrated 5ClU were calculated. In addition, 16 optimized transition‐state structures for water‐mediated catalysis on isomerizations of 5ClU were investigated. The forward and backward proton‐transfer energy barriers of water‐mediated catalysis on isomerizations of 5ClU were obtained. The results indicate that the catalytic effect of two H₂O molecules is much greater than that of one H₂O molecule in isomerizations of 5ClU.     

Influence of a quality system complying with the requirements of ISO/IEC 17025 standard on the management of a gamma-ray spectrometry laboratory

The motives for and the implementation of a quality system complying with the requirements of the ISO/IEC 17025 standard in a gamma-ray spectrometry laboratory are briefly described, as well as its influence on the laboratory's work and output. The use of the quality system as a tool for managing and controlling the state of the laboratory is described. Two examples of control and improvement of the laboratory's performance are given.     

A process approach to ISO/IEC 17025 in the implementation of a quality management system in testing laboratories

The introduction of quality management systems (QMS) and the accreditation of laboratories according to ISO/IEC 17025 standard are not easy tasks, mainly for those laboratories located at teaching and research institutions. During the implementation of QMS at two testing laboratories of the Federal University of Rio Grande do Sul in Brazil, new solutions to overcome some of the difficulties inherent to this type of environment have been found. The knowledge acquired through this work has led to the proposition of some general steps incorporating a process approach presented in this article, which could be of use to laboratories in their pursuit for accreditation. This proposal suggests the use of strategic planning information, links the QMS objectives to the corresponding processes and sets a few indicators to monitor both performance of and improvements to the system.     

The catalytic effect of Al-KIT-5 and KIT-5-SO<Subscript>3</Subscript>H on the conversion of fructose to 5-hydroxymethylfurfural

The aim of this work is to study the production of hydroxymethylfurfural (HMF) from fructose using heterogenous catalysts based on KIT-5. For this propose, Al-KIT-5 and KIT-5-SO₃H as the Lewis and Bronsted catalysts were prepared and were characterized using different techniques such as FT-IR, SEM, EDS, TEM, BET, TGA and elemental analysis. With the use of Al-KIT-5 as the catalyst, the appropriate reaction temperature and time were 135 °C and 60 min, respectively. Moreover, with the use of KIT-5-SO₃H as the catalyst, the proper reaction conditions were found to be 125 °C and 45 min, respectively. In addition, the corresponding amounts of catalyst weight were 40 and 50 mg for KIT-5-SO₃H and Al-KIT-5, respectively. Under these conditions, the conversion of fructose was 93.9 and 88.3%, respectively. These results indicated that, due to its Bronsted acid nature, the KIT-5-SO₃H catalyst showed better results when 40 mg catalyst was used at 125 °C for 45 min in DMSO as the solvent. Both catalysts could be recycled and reused several times.     

Plans for implementation of a quality system in the control laboratory of the Romanian National Medicines Agency

This paper describes the practical implementation of a quality system in the control laboratory of the National Medicines Agency, Romania, the main aim being the alignment of the requirements of the control of drugs in Romania with European Union standards. Activity in this field is relatively new in Romania, however, it is of great importance to Romania’s compliance with international standards. Received: 13 September 2000 Accepted: 19 February 2001     

Deoxy-nitrosugars. 5th Communication. The anomeric effect of the nitro group

The 1-deoxy-1-nitro-D -manno-pyranose 4 was transformed into the nitroolefin 5 and hence into the anomeric 1,2-dideoxy-1-nitro-3, 4, 6-tri-O-benzyl-D -arabino-hexopyranoses ( 3a and 3b ; cf. the Scheme). Conformational analysis of 1-benzyloxy-2-nitroethane ( 6 ) by ¹H-NMR spectroscopy (Fig. 2) showed the synclinal conformation to be more stable than the antiperiplanar one by about 1.4 kcal/mol (attractive gauche-effect). This gauche-effect favours the 1-deoxy-1-nitro-2, 3, 4, 6-tetra-O-benzyl-β-D -manno-hexopyranose ( 1b ) possessing an equatorial nitro group, which is, however, qualitatively the less stable anomer. The relative concentrations of the anomers of 1 and 3 , respectively, were determined by ¹H-NMR spectroscopy after base catalyzed equilibration at 37° in CHCl₃-solution (Table). Anomeric effects for the nitro group of approximately 2.4 kcal/mol in 3 and of approximately 3.4 kcal/mol in 1 were calculated.     

“Clinic laboratory accreditation with ISO 15189:2007 in the European Union”: report of the VI European symposium on clinical laboratory and in vitro diagnostic industry

Accreditation and Quality Assurance -     

The pH effect on the naphthoquinone-photosensitized oxidation of 5-methylcytosine

The pH effect on the one-electron photooxidation of 5-methyl-2'-deoxycytidine (d(m)C) by sensitization with 2-methyl-1,4-naphthoquinone (NQ) was investigated. Photoirradiation of an aqueous solution containing d(m)C and NQ under slightly acidic conditions of pH 5.0 efficiently produced 5-formyl-2'-deoxycytidine, whereas similar NQ-photosensitized oxidation of d(m)C proceeded to a lesser extent under more acidic or basic conditions. Fluorescence-quenching experiments revealed that the less-efficient photooxidation at pH values below 4.5 is attributed to the decreased rate of one-electron oxidation of d(m)C owing to protonation at the N(3)-position. The NQ-photosensitized oxidation of an N(4)-dimethyl-substituted d(m)C derivative under various pH conditions also suggests that the pH change in the range of 5.0 to 8.0 may be responsible for a reversible deprotonation-protonation equilibrium at the N(4)-exocyclic amino group of the d(m)C radical cation. In accord with the photochemical reactivity of monomeric d(m)C, the 5-methylcytosine residue in oligodeoxynucleotides was oxidized efficiently by photoexcited NQ-tethered oligodeoxynucleotides under slightly acidic conditions to form an alkali-labile 5-formylcytosine residue.     

ESR study on chemical crosslinking reaction mechanisms of polyethylene using a chemical agent—II. The effect of phenolic antioxidants

The effect of antioxidant on the reaction mechanism of chemical crosslinking of polyethylene (PE) with dicumyl peroxide (DCP) at high temperatures was investigated by electron spin resonance (ESR). The antioxidant reacts with the alkyl radicals in PE formed by the thermal decomposition of DCP above 120°C, and disturbs the crosslinking. A phenolic type antioxidant produced the phenoxy radical by the reaction with alkyl radicals formed in PE. It is suggested that the selection of a suitable antioxidant for PE crosslinking can be made by ESR analysis. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2431–2439, 1997     

Real‐time Fourier transform infrared study of the free‐radical ultraviolet‐induced polymerization of a hybrid sol–gel. II. The effect of physicochemical parameters on the photopolymerization kinetics

Free‐radical photocurable hybrid sol–gel materials have gained special interest during the last decades. Compared to thermally processed materials, they present the advantages of fast curing, low energy consumption, and spatiotemporal control of the reaction. Although comprehension of the photochemical step is fundamental, little is known about the characteristic of photochemistry in this kind of material. Real‐time Fourier transform infrared spectroscopy was used to study the photopolymerization of a hybrid sol–gel upon ultraviolet irradiation. Various photoinitiator systems were tested for their efficiency in inducing the polymerization of pendant polymerizable moieties anchored on a partially condensed silicate network. The presence of O₂ and the nature of the polymerizable function were shown to be crucial factors in the photoinduced process. The effects of the photoinitiator concentration and light intensity were also studied. These results were explained in terms of classical kinetic models developed for all‐organic photopolymers to point out the distinctive aspects related to the use of photoinitiated polymerization in hybrid sol–gel materials. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 831–840, 2003     

The effect of the silicon incorporation on the hydroxylapatite structure. A neutron diffraction study

Nominal stoichiometric hydroxylapatite, Ca₁₀(PO₄)₆(OH)₂ and silicon-substituted HA, containing 0.9 wt% in silicon, were prepared by the ceramic method. The samples were analyzed by elemental chemical analysis, Fourier transformed infrared spectroscopy (FTIR) and the structural study was carried out by Rietveld analysis combining powder X-ray (XRD) and neutron diffraction (ND). The refinements of the occupancies at the 4e Wyckoff position shows that the OH⁻/O²⁻ ratio is higher when SiO₄⁴⁻ substitutes PO₄³⁻. The observation of the Fourier maps points out that also the HPO₄²⁻ formation from PO₄³⁻ is also higher when Si is included in the HA structure. For the first time, the atomic coordinates for the H atoms of HPO₄²⁻ anions are provided.     

On the photochemical dimerization of some 5‐substituted 2‐styryl‐4‐pyrones. The effect of 5‐hydroxy‐/ 5‐methoxy‐substitution

Irradiation of styryl‐4‐pyrones 1a‐1d or 2a‐2e (6‐9 × 10^?3 M, methanol solution) with filtered (RAYONET photochemical reactor, 300 nm) or unfiltered uv‐light (high‐pressure mercury arc lamp) under aerobic conditions led mainly to dimeric products. Parent 5‐hydroxy‐substituted compounds 1a‐1d yielded exclusively “half‐cage” dimers 3a‐d characteristic for 4‐pyrone dimerization. 5‐Methoxy‐analogues 2a‐2e behave like typical stilbene structures and the mixture of tetrasubstituted cyclobutanes 4 and 5 accompanied with minor amount of phenanthrene‐like compound 6 were the only isolable products of the irradiation. The structure elucidation of products is based on spectral data obtained from MS, IR, ¹H NMR and ¹³C NMR spectra applying COSY, APT, HETCOR, HMBC and NOESY techniques.     

An implementation of the Deutsch–Jozsa algorithm on molecular vibronic coherences through four-wave mixing: a theoretical study

Time-frequency resolved coherent anti-Stokes Raman scattering (TFRCARS) was recently proposed as a means to implement quantum logic using the molecular ro-vibrational manifold as a quantum register [R. Zadoyan et al., Chem. Phys. 266 (2001) 323]. We give a concrete example of how this can be accomplished through an illustrative algorithm that solves the Deutsch–Jozsa (DJ) problem. We use realistic molecular parameters to recognize that, as the problem size expands, shaped pulses must be tailored to maintain fidelity of the algorithm.     

The effect of added liposomes on the rheological properties of a hydrogel: a systematic study

Rheological characteristics of liposome-containing-hydrogels were studied. Sonicated unilamellar vesicles (SUV), prepared by probe sonication and multilamellar vesicles (MLV) prepared by thin film hydration were loaded in a hydrogel containing carbopol 974 NF and hydroxyethylcellulose (Natrosol 250 HX). Phosphatidylcholine (PC) or hydrogenated-PC (HPC) liposomes, plain or mixed with cholesterol (chol) were used. Static (steady-stress sweep-tests) and dynamic (frequency sweep-tests) rheological measurements were carried out. All gels had a shear thinning behaviour (fitted well by Cross model). Zero-rate shear viscosity and power law index values, revealed that PC liposome addition in the hydrogel had minimum effect on its rheological properties even at the highest lipid concentration used (20 mg/ml). Oppositely, HPC (or HPC/chol) liposome addition resulted in significant modulations of the same rheological characteristics (which increased with increasing lipid concentration). HPC liposomes also caused a significant increase in gel relaxation time, which indicates that the elastic character of the gel strengthens as HPC liposome concentration increases. Concluding, liposome composition (membrane rigidity) and lipid concentration, but not liposome size, seem to be very important factors that determine the rheological modulations caused by liposome addition in gels.     

The central ion effect on the complex formation process in aqueous organic solvents. The Jahn-Teller effect in the Cu<Superscript>2+</Superscript> solutions

The complex formation of the Ni²⁺ and Cu²⁺ ions in aqueous solutions of 16 organic solvents of different nature (hydrophilic, hydrophobic, and neutral according to the dielectric data) was studied by the electronic spectroscopy. It was shown that in the case of nickel, the solvents under study behaved similarly (except for acetonitrile), i.e., were coordinated to the metal ion through oxygen, and turned weaker than water as regards the spectrochemical series. In the case of copper, the organic solvents exhibited their pronounced hydrophilic and hydrophobic nature. This is explained by nonequivalence of the equatorial and axial positions in the coordination polyhedron of copper due to the Jahn-Teller effect.