A radioanalytical technique for measurement of beta-glucuronidase activities

Summary Phenolphthalein-glucuronide is a commonly used glucuronide conjugate for beta-glucuronidase measurements. The quantity of phenolphthalein liberated by beta-glucuronidase is measured spectrophotometrically. The detection limit of the quantity of phenolphthalein using spectrophotometry is a few μg. In this study, a new radioanalytical technique for the measurement of beta-glucuronidase was applied which is 10⁶times more sensitive than the spectrophotometric technique. Radioiodinated phenolphthalein-glucuronide and phenyl-N-glucuronide were used in this study in which the beta-glucuronidase levels of some tissue samples were measured.     

A radioanalytical study of the chromate conversion coating formed on aluminium

Phosphate/chromate and accelerated chromate coatings were produced on commercially available aluminium. The Cr, P and Fe components of the conversion coatings were determined by radioactive tracer technique. The tracer technique was combined with ion-exchange and film-sectioning methods to determine the chromium (III)/total chromium ratio in the accelerated chromate coating. It was found that during the acidic dissolution of the conversion coating the chromium (III)/total chromium ratio may suffer changes. The filmforming components in the metal/bath interface are supersaturated and deposited onto the aluminium. The identified components of the accelerated chromate coatings are Cr/OH/₃, Cr/OH/CrO₄ and Cr₄[Fe/CN/₆]₃ and the chromium (III)/total chromium ratio was found to be cca. 2/3.     

Flow microcalorimetry applied to the study of chemical stability of organic compounds

This work reports on the possibility of using the LKB 2277 thermal activity monitor to study the influence of anionic, cationic and neutral surfactants on the stability of a series of an-alkyl acetates.Thermodynamic parameters as well as rate constants could be calculated.Two conclusions can be drawn: 1. The stability of esters increases with increasing concentrations of surfactants. 2. The stability of esters in the presence of surfactants increases with the chain length of the esters; the contribution of a CH₂ group to a higher stability of the esters in the presence of surfactants seems to be constant.

---

Zusammenfassung Das Kalorimeter LKB 2277 kann verwendet werden, um den Einfluss kationischer, anionischer und neutraler Tenside auf die Stabilität einer Serie von n-Alkylacetaten zu untersuchen. Thermodynamische Parameter und Geschwindigkeitskonstanten werden berechnet. Folgende Schlussfolgerungen werden gezogen: 1, Die Stabilität der Ester steigt mit zunehmender Tensidkonzentration. 2. In Gegenwart von Tensiden steigt die Stabilität mit zunehmender Kettenlänge des Esters, der Beitrag einer CH₂-Gruppe zur steigenden Stabilität des Esters scheint konstant zu sein.

---

2277 , - n- . . , - . ₂ - .

---

---

To the memory of Prof. Dr. A. Hulshoff     

A study of the photodegradation of polyvinyl chloride

Mass spectrometry has been used to examine the photoinduced dehydrochlorination of polyvinyl chloride films both in the absence and presence of titanium dioxide. Hydrogen chloride evolution was only observable when light of λ < 300 nm was used. The presence of titanium dioxide affords some protection. When light of λ > 300 nm is used photodegradation of added stabilisers is observed. Preliminary experiments indicate that rigid polyvinyl chloride behaves in a similar way to the film.By use of infra-red spectroscopy it was shown that polyvinyl chloride photodegrades in the presence of air to give carbonyl compounds, hydroperoxides and polyenes if light having λ < 300 nm is used. Added titanium dioxide can retard these processes. From these results and those obtained with light of λ > 300 nm, in which only carbonyl compound formation can be observed, it is proposed that the routes for carbonyl compound and hydroperoxide formation are not necessarily inter-related.     

A review on photodegradation of organic pollutants using spinel oxide

Spinel oxide has produced rapid improvement in various applications such as catalysis, sensors, batteries, degradation of dyes, drug delivery, and so on. In the current age, most of the researches are engrossed on spinel oxides for their photocatalytic activity because proficient exclusion of organic contaminants from wastewater has become a hot research topic by considering the environment. Photocatalytic degradation of organic contaminants is advantageous over conventional wastewater treatment technique like desalination, adsorption, and reverse osmosis. The current review demonstrates the photocatalytic activity of aluminate, ferrite spinel oxides, and modified spinel oxide for the removal of organic pollutants. This article comprises the structure, process of synthesis of spinel oxide, properties, photocatalytic activity, and reaction mechanism of degradation. In the end, future research needed to enhance the photocatalytic activity is discussed.     

Precipitation from homogeneous solution applied to the drop technique for the study of nucleation

The technique of precipitation from homogeneous solution has been successfully coupled with the drop technique for study of the nucleation process.     

Photocatalytic UV-degradation of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in the presence of silver doped zeolite

Silver incorporated into the Y zeolite framework was prepared and characterized. Low temperature luminescence analysis indicates the formation of silver-silver excimers (excited state dimers) and exciplexes (excited state trimers) that were found to be activated at 250 nm and 300 nm, respectively. The catalytic activity of the modified material was tested toward the photodecomposition of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). The site selective activity was evaluated using two sources of UV irradiation at 254 and 302 nm. The catalyst was found to effectively decompose TCDD in a methanol/tetrahydrofuran solution to reach 86% after 5 h. In the presence of the catalyst, a hydroxyl derivative was identified as an intermediate for the 302 nm catalytic pathway. This was not observed for the 254 nm process. Furthermore, irradiating of TCDD under 254 nm UV source for 6 h resulted in the formation of three products with molecular ion peaks of 113, 128, and 158 amu. On the other hand, the 302 nm gives two major products with molecular ion peaks of 220 and 252 amu. The study also indicates that the hydroxyl derivative could be potentially more toxic than the parent TCDD while all other isolated products were found to be less toxic than TCDD.     

Selective determination of 2,3,7,8-tetrachlorodibenzo-p-dioxin in the presence of a large excess of other polychlorinated dibenzodioxins and polychlorinated dibenzofurans

Summary A procedure is described for the selective separation of 2,3,7,8-TCDD from all other PCDDs and PCDFs. For this purpose the mixture of PCDDs and PCDFs is fractionated on Alumina Woelm B Super I in such a manner that all PCDDs and PCDFs are eluted prior to 2,3,7,8-TCDD. This procedure allows a more sensitive quantitative determination of 2,3,7,8-TCDD in samples which contain 2,3,7,8-TCDD only as a very minor fraction of the other TCDDs or PCDDs and PCDFs. Determination of 2,3,7,8-TCDD in pentachlorophenol and in a waste sample from 2,4-dichlorophenol production by this procedure is described.

---

Selektive Bestimmung von 2,3,7,8-Tetrachlordibenzo-p-dioxin in Gegenwart eines großen Überschusses anderer polychlorierter Dibenzodioxine und polychlorierter Dibenzofurane

Zusammenfassung Ein Verfahren wird beschrieben, das die selektive Abtrennung von 2,3,7,8-TCDD aus einer Mischung von allen PCDDs und PCDFs erlaubt. Dies geschieht durch Fraktionierung an Alumina Woelm B Super I, wodurch eine getrennte Elution aller PCDDs und PCDFs von 2,3,7,8-TCDD erreicht werden kann. Dieses Verfahren erlaubt die quantitative Bestimmung von 2,3,7,8-TCDD mit höherer Nachweisempfindlichkeit in Proben, die andere TCDDs bzw. PCDDs und PCDFs in extremen Überschüssen im Vergleich zu 2,3,7,8-TCDD enthalten. Am Beispiel der Bestimmung von 2,3,7,8-TCDD in Pentachlorphenol und in einem Produktionsrückstand von 2,4-Dichlorphenol wird die praktische Anwendbarkeit nachgewiesen.

---

---

This work was supported by the Ministerium für Ernährung, Landwirtschaft, Umwelt und Forsten, Baden-Württemberg.The skilfull technical assistance of Roland Kerzenmacher is acknowledged.     

Mechanism for semiquinone formation in the oxygen negative chemical ionization mass spectrometry of 2,3,7,8-tetrachlorodibenzo-p-dioxin

The high toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) has led to the development of selective and highly sensitive quantitative methods for mass spectral analysis. Analytical selectivity has been demonstrated for the oxygen negative chemical ionization (ONCI) reaction of TCDD in an oxygen-rich plasma. While the reaction product (4,5-dichloro-1,2-benzoquinone anion) of 2,3,7,8-TCDD and oxygen is well known, the mechanism of its formation has not been studied thoroughly. In this report the results of a study involving the reaction of ¹⁸O₂ with 2,3,7,8-TCDD under high pressure and low pressure ONCI conditions are reported. A mechanism is proposed which is compatible with the observation that one ¹⁸O atom is incorporated into the product anion.     

A morphology-related study on photodegradation of protein fibres

The wool fibre has a complex morphology, consisting of an outer layer of cuticle scales surrounding an inner cortex. These two components are hard to separate effectively except by using harsh chemical treatments, making it difficult to determine the susceptibility of the different components of the fibre to photoyellowing. An approach to this problem based on mechanical fibre modification is described. To expose the inner cortex of wool to different degrees, clean wool fibres were converted into 'powders' of various fineness via mechanical chopping, air-jet milling, ball milling or their combination. Four types of powdered wool (samples A, B, C and D) were produced with reducing particle size distributions and an increasing level of surface damage as observed using SEM. Sample A contained essentially intact short fibre snippets and sample D contained a large amount of exposed cortical materials. Samples B and C contained a mixture of short fibre snippets and cortical materials. Solid wool discs were then compressed from the corresponding powder samples in a polished stainless steel die to enable colour measurement and UV irradiation studies. ATR-FTIR studies on powder discs demonstrated a small shift in the amide I band from 1644cm(-1) for disc A to 1654cm(-1) for disc D due to the different structures of the wool cuticle and cortex, in agreement with previous studies. Similarly an increase in the intensity ratio of the amide I to amide II band (1540cm(-1)) was observed for disc D, which contains a higher fraction of cortical material at the surface of the disc. Discs prepared from sample D appeared the lightest in colour before exposure and had the slowest photoyellowing rate, whereas discs made from powders A-C with a higher level of cuticle coverage were more yellow before exposure and experienced a faster rate of photoyellowing. This suggests that the yellow chromophores of wool may be more prevalent in cuticle scales, and that wool photoyellowing occurs to a greater extent in the cuticle than in the cortex. Photo-induced chemiluminescence measurements showed that sample D had a higher chemiluminescence intensity after exposure to UVA radiation and a faster decay rate than samples A and B. Thus one of the roles of the wool cuticle may be to protect the cortex by quenching of free radical oxidation during exposure to the UV wavelengths present in sunlight.     

A concomitant use of some radioanalytical and metallurgical methods: Application to the study of the thermal oxidation of titanium

Polycrystalline titanium samples were oxidized in pure oxygen under a 75 torr pressure, at temperatures ranging from 400°C to 500°C, and for times up to 2 hrs. A similar treatment was applied to some single crystal samples, so as to show the relationship between the crystallite orientation and the oxidation rate. The oxide films were studied by means of radioanalytical techniques, such as nuclear microanalysis, electron diffraction and ESCA, in addition to most classical techniques such as optical and electron microscopy. The complementary side of these methods is showed. They permit us to determine the contamination of the metallic surface introduced by the polishing treatments, the oxidation rate at constant temperature, and the structure of the oxides which exists in the films. These ones are especially TiO₂, Ti₃O₅, Ti₂O₃ and TiO.     

Characterization of polyoxometalate/polymer photo-composites: A toolbox for the photodegradation of organic pollutants

Different inorganic/organic photocomposites based on polyoxometalate (POM) nanoparticles have been developed for photocatalytic applications. Currently, polyoxometalate nanoparticles have been successfully in-situ embedded into an acrylate polymer network by photopolymerization upon mild visible light irradiation at 405 nm. The proposed POM/polymer photocomposites have been characterized using complementary techniques for a better understanding of their photocatalytic activity. Interestingly, the obtained photocomposites exhibit high rigidity, excellent thermal stability, a non-negligible porosity and new functionalities such as light reactivity and redox properties. Moreover, developed composites showed efficient catalytic activity for the color removal of aqueous solutions of erythrosine and rose Bengal under Light Emitting Diodes LED@375 nm irradiation reaching 80 and 90% as a final color removal, respectively.     

用NMR研究D-葡萄糖在碱性溶液内的行为

葡萄糖在碱性溶液中存在异构化、解离和溶剂化三种作用,但葡萄糖的中性、碱性溶液~(13)CNMR图谱几乎没有变化。我们测定了葡萄糖、果糖和甘露糖在不同pH的~(13)CNMR;也测定了葡萄糖的中性、碱性水溶液的~1HNMR,用INDOR法确定其H_((1)),H_((2))峰,并和葡萄糖分子、离子和水合离子的EHMO计算结果对照分析,说明了葡萄糖图谱不变的原因。     

Evaluation of anion exchange resins Tulsion A-30 and Indion-930A by application of radioanalytical technique

Radioanalytical technique using ¹³¹I and ⁸²Br was employed to evaluate organic based anion exchange resins Tulsion A-30 and Indion-930A. The evaluation was based on performance of these resins during iodide and bromide ion-isotopic exchange reactions. It was observed that for iodide ion-isotopic exchange reaction by using Tulsion A-30 resin, the values of specific reaction rate (min^?1), amount of iodide ion exchanged (mmol), initial rate of iodide ion exchange (mmol/min) and logK _d were 0.238, 0.477, 0.114, and 11.0, respectively, which was higher than 0.155, 0.360, 0.056, and 7.3, respectively as that obtained by using Indion-930A resins under identical experimental conditions of 40.0°C, 1.000 g of ion exchange resins and 0.003 M labeled iodide ion solution. Also at a constant temperature of 40.0°C, as the concentration of labeled iodide ion solution increases 0.001 to 0.004 M, for Tulsion A-30 resins the percentage of iodide ions exchanged increases from 59.0 to 65.1%, and from 46.4 to 48.8% for Indion-930A resins under identical experimental conditions. The identical trend was observed for both the resins during bromide ion-isotopic exchange reactions. The overall results indicate that under identical experimental conditions, Tulsion A-30 show superior performance over Indion-930A resins. The results of present experimental work have demonstrated that the radioanalytical technique used here can be successfully applied for characterization of different ion exchange resins so as to evaluate their performance under various process parameters.     

A photoplate calibration technique applied to the determination of hafnium in zirconium by SSMS

A photoplate calibration procedure is suggested for spark source mass spectrometry /SSMS/ with photoplate detection. The technique uses the Churchill two-line method applied to the two stable isotopes of copper. The calibration curve thus obtained is split into fragments and each fragment is approximated by a polynomial. The method was applied for the quantitative determination of Hf as impurity in zirconium sponge obtained from a pilot plant dedicated to the depletion of the hafnium content in zirconium by fractional crystallization.     

Phthalhydrazide nanoparticles as new highly reusable organic photocatalyst in the photodegradation of organic and inorganic contaminants

Phthalhydrazide nanoparticles are introduced as a new, efficient, stable and reusable organic photocatalyst for the photodegradation of a range of azo dyes, including methyl orange, methyl red, congo red and yellow titan, 4‐nitrophenol and permanganate as important organic and inorganic contaminants. Various experimental parameters including pH, photocatalyst dose, dye concentration and illumination time were investigated for methyl orange as a model substrate. The results revealed high degradation efficacy, up to 93.6%, for methyl orange in 20 min. Moreover, a preliminary kinetic study along with a proposed photodegradation mechanism is included in this study. Mechanistic investigations showed that phthalhydrazide behaved as a photoreduction catalyst. With the addition of Cl^? ion, as a hole scavenger, photodegradation efficacy for methyl orange was improved. Results showed that phthalhydrazide nanoparticles behaved better than commercial bulk phthalhydrazide and both performed as successful photocatalysts for photoreduction of the mentioned organic and inorganic compounds.     

A new technique to determine organic and inorganic acid contamination

A new acid indicator pad was developed for the detection of acid breakthrough of gloves and chemical protective clothing. The pad carries a reagent which responds to acid contaminant by producing a color change. The pad was used to detect both organic and inorganic acids permeating through glove materials using the modified ASTM F-739 and direct permeability testing procedures. Breakthrough times for each type of glove were determined, and found to range from 4 min to > 4 h for propionic acid, from 3 min to > 4 h for acrylic acid, and from 26 min to > 4 h for HCl. A quantification was performed for propionic and acrylic acids following solvent desorption and gas chromatography. Both acids exhibited > 99% adsorption [the acid and its reactivity (the acid reacted with an indicator to contribute the color change)] on the pads at a spiking level of 1.8 microL for each acid. Acid recovery during quantification was calculated for each acid, ranging from 52-72% (RSD < or = 4.0%) for both acids over the spiking range 0.2-1.8 microL. The quantitative mass of the acids on the pads at the time of breakthrough detection ranged from 260-282 and 270-296 microg cm(-2) for propionic acid and acrylic acid, respectively. The new colorimetric indicator pad should be useful in detecting and collecting acid permeation samples through gloves and chemical protective clothing in both laboratory and field studies, for quantitative analysis.     

A resonance light scattering ratiometry applied for binding study of organic small molecules with biopolymer

Resonance light scattering (RLS) technique is a creative application of light scattering signals detected by using a common spectrofluorometer, but it has drawbacks such as the fluctuation of signals caused by poorly quantified or variable factors. Herein we develop a RLS ratiometry to overcome the drawbacks of the technique and apply to measure the binding nature of organic small molecules (OSM) with biopolymer using the binding of cation porphyrins with heparin (HP) as an example. In near neutral solution, cationic porphyrins meso-tetrakis [(trimethylammoniumyl) phenyl] porphyrin (TAPP) and meso-tetra (4-methylpyridy) porphyrin (TMPyP-4) interact with heparin, resulting in hypochromatic effect, and enhanced RLS signals. Linear relationship could be established between the ratio of enhanced RLS signals at two wavelengths, where the maximum and minimum are available in the ratio curve of UV-vis spectrum of porphyrin to that of heparin-porphyrin complex, and the logarithm of heparin concentration, and thus a wide dynamic range detection method of biopolymers could be developed. In comparison with RLS method, this RLS ratiometric one is less affected by environmental conditions such as pH, ionic strength. The mechanism of these interactions was investigated based on the charge density distribution of the two porphyrin molecules and it could be concluded that the enhanced RLS intensity is proportionally promoted by the charge capacity of components in the complex. Additionally, the binding number and binding constant were measured scientifically by Scatchard plot.     

A polycationic pillar[5]arene for the binding and removal of organic toxicants from aqueous media

ABSTRACT

The ability to bind and detect analytes with high levels of selectivity, sensitivity and broad applicability for a variety of analytes is an essential goal, with applications in public health and environmental remediation. Methods to achieve effective binding and detection include electrochemical, and spectroscopic methods. The use of supramolecular chemistry to accomplish such detection, by binding a target in a host and transducing that binding into a measurable signal, has advantages, including tunability of the sensor and the ability to rationally design hosts through an understanding of non-covalent interactions. Reported herein is the design and use of pillar[5]arenes to accomplish precisely such detection. Water-soluble pillar[5]arenes containing 10 cationic linker arms on their periphery bound toxicants in their hydrophobic cores with association constants of 10⁵–10⁶M^?1. With the use of cationic exchange resins, the pillar[5]arene hosts were removed from solution with their encapsulated guests, allowing for effective toxicant removal.