Lifetime prediction of a blue PE100 water pipe

The traditional method to assess the lifetime of plastic pipes is based on hydrostatic pressure testing. A complementary approach has been conducted to monitor the depletion of antioxidants and initiation of thermo-oxidative degradation on a PE100 blue water pipe that had been exposed to hydrostatic pressure in water at low test temperatures (maximum 80 °C).Depletion of antioxidants was monitored using OIT testing and initiation of thermo-oxidative degradation was assessed by iodometric detection of hydroperoxides. An empirical model based on the Arrhenius fit of the data was developed to extrapolate the lifetime of the PE100 pipe material at various service temperatures (10-25 °C). Associated activation energies, E_a, were determined and appeared to be in line with the values obtained from experiments carried out at low test temperatures. The combination of pressure testing and chemical analyses proved to be a very powerful tool to extrapolate the lifetime of plastic pipes.     

Simultaneous determination of trace level bromate and chlorinated haloacetic acids in bottled drinking water by ion chromatography

A convenient and sensitive method for the simultaneous determination of trace level of bromate and chlorinated haloacetic acids in bottled drinking water with ion chromatography is presented. With a high capacity anion-exchange column and 11.5 mmol/l Na₂CO₃ eluent, all the 16 analytes could be separated in one injection within 31 min. By employing a microwave based evaporation technique, the bottled drinking water sample could be concentrated tenfold in 10 min. The recoveries of the compounds ranged from 90.6 to 107.2%. With a 500 μl large volume injection and high performance anion Atlas electrolytic suppressor, the detection limits were 0.06, 0.08, 0.06, 0.14 and 0.85 μg/l for BrO₃⁻, ClO₃⁻, monoacetic acid, dichloroacetic acid and trichloroacetic acid, respectively.     

HS-SPME-GC-MS analysis of antioxidant degradation products migrating to drinking water from PE materials and PEX pipes

Polyethylene (PE) and cross-linked polyethylene (PEX) pipes are frequently used in water supply systems. Such pipes contain added antioxidants with phenolic structures, e.g. Irgafos 168, Irganox 1010 and 1076, in order to improve durability. However, phenol, ketone and quinone antioxidant degradation products may leach and enter drinking water. The aim of this investigation was to develop a method for measuring these degradation products with a performance meeting the drinking water quality criteria of 20?µg?L^?1. Using headspace solid phase microextraction coupled to a gas chromatograph with a mass spectrometer, a method was established revealing limits of detection and quantification less than 0.4 and 1?µg?L^?1 respectively. The method was applied to migration experiments for two PEX pipes and one PE material, quantifying the release of two degradation products. Highest concentrations were observed for 2,6-di-tert-butyl-p-benzoquinone which in one of the two pipes was found in concentrations of 18–57?µg?L^?1 in each of eight consecutive release experiments.     

Supported liquid membrane work-up in combination with liquid chromatography and electrochemical detection for the determination of chlorinated phenols in natural water samples

Summary A sample preparation method has been developed for the determination of chlorinated phenols in water. The method is based on a supported liquid membrane extraction system connected on-line to liquid chromatography with electrochemical detection. The supported liquid membrane technique utilizes a porous PTFE membrane. The membrane is impregnated with an organic solvent which forms a barrier between two aqueous phases and enables selective extraction. The technique can easily be coupled in a flow system. In this investigation five chlorinated phenols (1–5 chlorine atoms) were extracted from natural water samples. Extraction for 30 minutes resulted in detection limits of approximately 25 ng L^–1.     

Lifetime predictions for semi-crystalline cable insulation materials: I. Mechanical properties and oxygen consumption measurements on EPR materials

Long-term accelerated aging studies (up to 7 years of aging) were conducted on four typical EPR materials used as cable insulation in nuclear power plant safety applications with the goal of establishing lifetime estimates at typical aging conditions of ∼50 °C. The four materials showed slow to moderate changes in mechanical properties (tensile elongation) until just before failure where abrupt changes occurred (so-called “induction-time” behavior). Time-temperature superposition was applied to derive shift factors and probe for Arrhenius behavior. Three of the materials showed reasonable time-temperature superposition with the empirically derived shift factors yielding an approximate Arrhenius dependence on temperature. Since the elongation results for the fourth material could not be successfully superposed, consistency with Arrhenius assumptions was impossible. For this material the early part of the mechanical degradation appeared to have an Arrhenius activation energy E_a of ∼100 kJ/mol (24 kcal/mol) whereas the post-induction degradation data had an E_a of ∼128 kJ/mol. Oxygen consumption measurements were used to confirm the 100 kJ/mol E_a found from early-time elongation results and to show that the chemistry responsible before the induction time is likely to remain unchanged down to 50 °C. Reasonable extrapolations of the induction-time results indicated 50 °C lifetimes exceeding 300 years for all four materials.     

Gene-expression profiling in gill and liver of zebrafish exposed to produced water

The effects of produced water (a by-product of oil and gas extraction) on gene expression were studied in gills and liver tissues of zebrafish. Adult, non-breeding zebrafish were exposed to control (freshwater mixed with 5% seawater) or produced water (freshwater mixed with 5% of produced water from the Oceberg C Oil Platform in the North Sea). A zebrafish library was used to make a microarray that consisted of 15,806 unique genes. The results indicate that 27 genes in the gills and 55 genes in the liver show significantly altered expression (greater than two-fold change). More than 70% of these gene sequences have not been annotated in the Gene Ontology (GO) database, making it difficult to characterize the affected genes. CYP1A displayed the greatest upregulation in the gills (eightfold, verified with quantitative real-time PCR). This study illustrates the utility of microarray approaches in investigations of environmental effects of toxicants.     

Decompression wave speed and crack velocity measurements during S4 test in water pressurized plastic pipes: Part 1. Experimental methods

In a Small Scale Steady State (S4) test apparatus of ISO 13477, instrumentations were designed and successfully adapted to determine decompression wave speed and crack velocity during rapid crack propagation event in water-filled plastic pipes. The basic design for decompression wave speed measurement involved the use of high-frequency dynamic pressure transmitters, located external to the water-filled pipe and connected to pressure measurement positions inside the pipe, by means of stainless steel tubes. For the crack velocity measurements, timing wire system with the required circuitry capable of giving the precise temporal indication of the propagating crack was designed and employed. In this paper, detailed design of instrumentations adapted to the S4 test apparatus and the assessment techniques used to obtain decompression wave speed and crack velocity are described. It was also demonstrated that the methods developed were viable for these measurements which are known to affect the rapid crack propagation behavior in water-filled plastic pipes.     

Hydroxyethyl curdlan as a novel water soluble derivative: Synthesis,characterization, and antioxidant capacity

In this study, hydroxyethyl curdlans (HeCDs) with different molecular weights were successfully fabricated. The structure and properties of the synthesized HeCDs were measured by FTIR, ¹³C nuclear magnetic resonance (NMR), and Raman spectroscopy and compared with curdlan. The degree of crystallinity of HeCDs was measured with X-ray diffractometry (XRD). Differential scanning calorimetry and thermogravimetric analysis were performed to determine thermal properties of HeCs. Solubility of HeCDs was tested in water, common organic solvents, and NaOH solution. Antioxidant activities of HeCs were investigated using various in vitro assay systems. The HeCDs exhibited a dose-dependent free radical scavenging activity as shown by their DPPH radical, ABTS radical and superoxide anion radical inhibition, and ferrous chelating ability and reducing power. The improved water solubility property and antioxidant activity of these curdlan derivatives could have a wide range of applications, particularly its use as an antioxidant in food, food packaging, biomedical, and pharmaceutical industries.     

Determination of acidic chlorinated pesticides in water: Comparison of official EPA method 515.1 and liquid-solid extraction HPLC/UV and HPLC/PBMS analyses

Summary A comparison of the official EPA method 515.1 for determination of chlorinated acidic pesticides and a modification of it is illustrated. Extraction of the analytes from water and their determination and quantitation is by gas chromatography-electron capture detection (GC-ECD), liquid chromatography-UV detection and liquid chromatography-particle beam mass spectrometry. Although HPLC-PBMS was found to be less sensitive than the GC-ECD method, it was, nevertheless, more sensitive than HPLC-UV. The modified method is simpler, quicker and allows more accurate determination of pesticides in aqueous samples.Deceased July 31, 1996     

Screening and identification of unknown contaminants in water destined to human consumption: A case study

As a response to a recent emergency case of suspected deliberate contamination of bottled drinking water addressed to sensitive personalities, samples were submitted to our laboratory for investigation; an analytical framework for wide screening and identification of unknown hazardous chemicals and microbiological agents in water has been developed and experienced for the purpose. The proposed approach combines several physico-chemical (inverse-phase liquid chromatography with spectrophotometric or mass spectrometric detection, suppressed ion chromatography, inductively coupled plasma-optical emission spectrometry, gas chromatography with mass spectrometric detection), microbiological (defined substrate technology) and biological assays (viability and macromolecular synthesis of cultured cells), thus allowing the detection of different classes of contaminants (inorganic and organic compounds, metals, algal toxins, bacterial indicators of faecal contamination, enteric pathogens, staphylococci, actinomycetes) and their effects.The application of the developed strategy to the suspected samples did not highlight the presence of specific and considerable risks for human health although a few organoleptic and microbiological parameters were compromised and water was not suitable for human consumption. Therefore, we were able to classify this episode as a water contamination threat instead of confirming an incident.The proposed screening-confirmatory analytical scheme can be a valuable tool for obtaining conclusive and relatively rapid results in investigations concerning accidental or intentional contamination of drinking water.     

Alterations in osmoregulation, antioxidant enzymes and indole alkaloid levels in Catharanthus roseus exposed to water deficit

Catharanthus roseus (L.) G. Don plants were grown in different water regimes in order to study the drought induced osmotic stress and proline (PRO) metabolism, antioxidative enzyme activities and indole alkaloid accumulation. The plants under pot culture were subjected to 10, 15 and 20 days interval drought (DID) stress from 30 days after sowing (DAS) and regular irrigation was kept as control. The plants were uprooted on 41 DAS (10 DID), 46 DAS (15 DID) and 51 DAS (20 DID). The drought stressed plants showed increased aminoacid (AA), glycine betaine (GB) and PRO contents and decreased proline oxidase (PROX) and increased γ-glutamyl kinase (γ-GK) activities when compared to control. The antioxidative enzymes like peroxidase (POX) and polyphenol oxidase (PPO) increased to a significant level in drought stressed plants when compared to control. The drought stressed C. roseus plants showed an increase in total indole alkaloid content in shoots and roots when compared to well-watered control plants. Our results suggest that the cultivation of medicinal plants like C. roseus in water deficit areas would increase its PRO metabolism, osmoregulation, defense system and the level of active principles.     

FTIR and fluorescence studies on the ground and excited state hydrogen-bonding interactions between 1-methylindole and water in water–triethylamine mixtures

The ground and excited state π-hydrogen-bonding interactions between 1-methylindole, MI, and water have been investigated in water–triethylamine, water–TEA, mixtures. FTIR measurements performed on the OH stretching bands of the water–TEA clusters show that, upon MI addition, the typical bands of the water–TEA system at 3348 cm⁻¹, 3440 cm⁻¹, 3545 cm⁻¹ and 3682 cm⁻¹ diminish, whereas two new absorption bands at 3316 cm⁻¹ and 3654 cm⁻¹ grow up. These spectral changes have been rationalised assuming the formation of only one 1:1 water–MI complex, in which the dangling protons in the water–TEA clusters are hydrogen bonded to the π-cloud of the MI aromatic ring. Steady state and time resolved fluorescence measurements provide additional proofs on the ground state formation of a fluorescent OH ? π hydrogen bonded complex. The relevance that the present and the previously reported results could have on the indole ring photophysics is discussed.     

Heats of solution of 1∶1 electrolytes in 1-propanol,and derived enthalpies of transfer from water

Heats of solution of 13 11 electrolytes in 1-propanol have been determined calorimetrically at various electrolyte concentrations, and extrapolated to zero concentration to give H _s ^o values for these electrolytes. Together with literature data on three additional 11 electrolytes, these measurements yield a self-consistent set of single-ion enthalpies of transfer from water to 1-propanol. Values are tabulated for 10 univalent cations and five univalent anions. It is shown that the H _t ^o (Ph ₄ As⁺)=H _t ^o (Ph ₄ B^–) assumption yields chemically reasonable single-ion values. Using this assumption, it may be deduced that all the univalent ions studied have about the same enthalpy in 1-propanol as in methanol.     

Synthesis of amphiphilic sulfonamide halogenated porphyrins: MALDI-TOFMS characterization and evaluation of 1-octanol/water partition coefficients

Porphyrins are key precursors for development of photosensitizers for photodynamic therapy. A new series of ortho-halogenated tetraarylporphyrins with sulfonamide substituents have been synthesized via chlorosulfonation reaction and characterized by MALDI-TOFMS. To predict their partition properties, log K_OW of a selected range of the synthesized halogenated amphiphilic porphyrins is described. A significant effect of the number and type of halogen group as well as on the number of sulfonamide side chain was observed. The determined 1-octanol/water partition coefficients showed that it is possible to obtain compounds with a wide range of lipophilicities, from log K_OW=−2.71 till log K_OW>4, which are suitable to optimize the biological efficacy of this class of sensitizers.     

An interlaboratory study to improve the quality of chemical and biological measurements in waste water

 Analyses of waste water are routinely performed to monitor the level of contamination. To verify the quality of such determinations the National Institute of Chemistry, with the support of the Ministry of Environment and Spatial Planning and the Slovenian Accreditation Agency, organizes interlaboratory comparisons. Over the last 3 years, five interlaboratory trials named "MPP-Waste Water" were organized. Each round attracted around 50 participants, mostly from Slovenia and some from abroad, which enabled the testing of SIST ISO methods or alternative methods. We prepared samples for determination of harmful substances that are important for the characterization of waste water; physico-chemical parameters (pH), global parameters – chemical oxygen demand (COD), biochemical oxygen demand (BOD₅), metals (mercury, cadmium, copper, nickel, lead and chromium (VI)), nutrients (ammonia and total phosphorus), anions (chloride, nitrite, nitrate, sulphate) and toxicity to Daphnia magna. For the analysis of each parameter we prepared two samples at two different concentration levels. The materials used in the proficiency testing were carefully prepared and their homogeneity and stability were verified. The purpose of this scheme was to enable participants to check their day-to-day analytical performance. The results should enable the participants to improve the quality of their analyses.

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Received: 24 October 2002 Accepted: 2 January 2003

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Acknowledgments We would like to thank the Ministry of Environment and Spatial Planning and the Ministry for Education, Science and Sport for providing financial support. We would like to thank members of the Technical Committee: Mrs. Marjana Kovacˇicˇ, Dr. Katja Otrin-Debevc, Prof. Dr. Marjan Veber and Mrs. Boža Gregorc for their valuable support. Special thanks are due to Dr. Adrian Van der Veen who helped us in running the first PT.

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Presented at CERMM-3, Central European Reference Materials and Measurements Conference: The function of reference materials in the measurement process, May 30–June 1, 2002, Rogaška Slatina, Slovenia

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Correspondence to M. Cotman     

Evaluation of some functionalized imidazoles and 1,2,4-triazoles as antioxidant additives for industrial lubricating oils and correlating the results with the structures of additives using empirical AM1 calculations

Functionalized 4,5-diphenyl-imidazoles, 4,5-diphenyl-1,2,4-triazoles and 5-(o-hydroxyphenyl)-4-phenyl-1,2,4-triazoles at the 2-position with thiol, thiomethyl and thiobenzyl groups, have been tested as antioxidant additives for lubricating oils. Whereas the thiomethyl groups in such compounds increased the antioxidant property than the thiol group, the corresponding thiobenzyl groups did the reverse. The results can be explained, based on correlating the electron donating and withdrawing abilities of the substituents with the oxidation stability. The triazoles carrying a phenolic hydroxyl group have more antioxidant power than those without such a group. The imidazoles gave the oils more oxidation stabilities than the two types of triazoles with the same functionalities. The 4,5-diphenyl-2-thiomethyl-imidazole (2), as an additive, has the highest antioxidant property, reaching the level of standard one when its concentration is 1.0% wt. instead of the 0.8% wt. of the standard. The correlation of the antioxidant character of the heterocyclic additives with their structures has been investigated using the semiempirical gas phase AM1 calculations for the studied heterocycles. The relative stability of the imidazoles 1 and 3 compared to 2 were in the order 2 > 1 > 3. Similarly, the relative stability of the triazoles are in the same order where 5 > 4 > 6 and 8 > 7 > 9.     

1H pulsed NMR study of bombyx mori silk fibroin: Dynamics of fibroin and of absorbed water

The dynamical behavior of the Bombyx mori silk fibroin chain and of absorbed water in silk fiber, film, and powder has been studied by ¹H pulsed nuclear magnetic resonance (NMR). Segmental motions do not occur and only the rapid rotation of the methyl groups of alanine residues is observed from ?120 to 130°C. This is independent of the conformation or form of the silk fibroin samples. Magnetization of dry silk fibroin by the solid-echo method shows a single Gaussian decay, while two components are observed in the solid-echo signals of films containing 6–10 w/w% water. An immobile component with a T₂ value of 11 μs is attributed to silk fibroin, and the mobile component to bound water. The T₂ of the latter varies from 50 to 200 μs, depending on the sample. The dynamical behavior of water trapped in the film is discussed on the basis of these T₂ values.     

Can clustering of liquid water and thermal analysis be of assistance for better understanding of biological germplasm exposed to ultra-low temperatures

Plausible effect of clustering of undercooled liquid water (pentamer configuration, icosahedra formation) is discussed showing water continuous but non-periodic patterns and its impact to the either formation of ice-crystals or ice-glass, particularly when making contact with plants. These processes are viable for the cryogenic storage of biological germplasm and subject for thermoanalytical studies aimed to the determination of glass transition temperatures.     

Methyl cellulose-based edible films and coatings I. Effect of plasticizer content on water and 1-octen-3-ol sorption and transport

Edible films were prepared from methyl cellulose with various concentrations of poly(ethylene glycol) 400 (PEG400) used as a plasticizer. Water vapour and 1-octen-3-ol (an aroma compound) were selected as hydrophilic and hydrophobic volatile penetrants respectively. Their solubility and permeability through methyl cellulose-based edible films were studied using gas chromatography methods. Whatever penetrant was used, the flux increased with the PEG400 content. Transfer behaviour, i.e., the order of increased magnitude of the transfer rate, strongly depends on the nature of the volatile compound. However, water sorption only depends on the PEG400 content whereas the aroma compound sorption is affected by both the water and the PEG400 concentrations. Relationships between solubility and permeability can be partially explained by the plasticization phenomenon.