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Mikael Krysell Roland Becker Jan Willem Wegener Hans-Gerhard Buge 《Accreditation and quality assurance》2008,13(10):553-562
As an answer to the re-evaluation of the European sludge directive, two novel reference materials for organic components in
municipal sludge have been produced and test certified for AOX (absorbable organic halogens), PAH (polycyclic aromatic hydrocarbons),
NPE (nonylphenol and nonylphenolethoxylates), DEHP (di(2-ethylhexyl)phthalate), bisphenol A, and BFR (brominated flame retardants).
The materials were prepared from raw sludge without spiking or mixing of different sludges. The study demonstrated that the
technique for the preparation of a suitable reference material, sufficiently homogenous and stable, and with concentration
levels that answer the needs of the laboratories and the relevant authorities, can now be presented in detail. The results,
furthermore, show there is a need for method validation and standardisation of the measurements of NPEs and certain BFR congeners,
and that the development of the laboratory structure in Europe, with fewer and more specialised laboratories, might become
a major obstacle when trying to find a sufficient number of laboratories being appropriately proficient for this kind of study
in the future. 相似文献
2.
Vermeir S Hertog ML Schenk A Beullens K Nicolaï BM Lammertyn J 《Analytica chimica acta》2008,618(1):94-101
In this paper, we compare and evaluate the applicability of three UV-VIS absorbance based assays for high-throughput quantification of ascorbic acid in horticultural products. All the methods involve the use of a common enzyme (ascorbate oxidase) in combination with a different indicator molecule. The three methods were retrieved from literature: a direct oxidase-method, an OPDA coupled oxidase-method and a PMS-method, which is commercially available. The analysis in high-throughput context involved the analysis in microplates in combination with the use of an automated liquid handling system. We checked (i) the performance factors of the selected methods on standard solutions, (ii) the applicability of the defined methods in high-throughput context, and, (iii) the accuracy of the methods on real samples using HPLC as a reference technique. The OPDA-method was found to be the most appropriate method for the quantification of ascorbic acid in high-throughput context with a linear range between 7.0 and 950 mg L−1 and excellent correlation parameters (slopes close to 1, intercepts close to 0, R2 > 0.91) with the reference technique when real samples were analyzed. Finally, this method was optimized for assay cost and assay time. Hereto the enzymatic reaction was mathematically described using a model for enzyme kinetics, which was then used to calculate the optimal concentrations of ascorbate oxidase and OPDA. As a result of the modeling the amount of enzyme in the assay could be reduced with a factor 2.5 without affecting significantly the reaction time. In a last step the optimal concentrations were used for a successful validation with the HPLC-reference technique. 相似文献
3.
《中国化学快报》2021,32(8):2544-2550
Recently, the degradation of organic compounds in saline dye wastewater by sulfate radicals (SO4−)-based advanced oxidation processes (AOPs) have attracted much attention. However, previous studies on these systems have selected non-chlorinated dyes as model compounds, and little is known about the transformation of chlorinated dyes in such systems. In this study, acid yellow 17 (AY-17) was selected as a model of chlorinated contaminants, and the degradation kinetics and evolution of oxidation byproducts were investigated in the UV/PDS system. AY-17 can be efficiently degraded (over 98% decolorization) under 90 min irradiation at pH 2.0–3.0, and the reaction follows pseudo-first order kinetics. Cl‒ accelerated the degradation of AY-17, but simultaneously led to an undesirable increase of absorbable organic halogen (AOX). Several chlorinated byproducts were identified by liquid chromatography-mass spectrometry (LC–MS/MS) in the UV/PDS system. It indicates that endogenic chlorine and exogenic Cl– reacted with SO4− to form chloride radicals, which are involved in the dechlorination and rechlorination of AY-17 and intermediates. The possible degradation mechanisms of AY-17 photooxidative degradation are proposed. This work provides valuable information for further studies on the role of exogenic chloride in the degradation of chlorinated azo dyes and the kinetic parameters in the PDS-based oxidation process. 相似文献
4.
The reuse of treated wastewater and its release into the environment calls for a validated method for the determination of
toxic compounds. We validate the method recommended by EN 1485 standard for AOX that are water soluble organic halides and
describe it in two parts. The first part shows the validation by parameters such as applicability, accuracy, and reproducibility.
After testing the normality of the statistical distribution of “the measured AOX concentration”, linearity, repeatability,
limits of detection and limits of quantitation are calculated. The second part describes the routine use of the validated
method. 相似文献
5.
建立了一种对纺织品中可吸附有机卤化物(AOX)的超声提取-高温燃烧吸收-离子色谱定量检测分析新方法。该方法采用超声方式提取纺织品中的AOX,提取液加入活性炭进行振荡吸附,并用酸性硝酸钠溶液对无机卤化物进行去除。采用程序升温的氧化燃烧方式对吸附AOX的活性炭进行裂解、燃烧及气化,其产生的卤化氢等气体随载气进入吸收液并完全转化为无机卤素阴离子,采用离子色谱分离测定,外标法定量。实验优化了超声提取时间、活性炭用量、燃烧气及其流量、燃烧升温程序、吸收液和吸收方式等前处理条件,并对离子色谱的仪器分析条件如色谱柱、柱温及淋洗液流速等进行优化。结果表明,氟、氯、溴、碘4种卤素离子的标准溶液在0.02~10 mg/L范围内呈线性关系,线性相关系数(R^(2))均在0.999以上;AOX测定的方法定量限为0.10~0.50 mg/kg。以棉、毛和涤纶3种不同种类的阴性纺织样品作为样品基质,选取典型的有机卤化物进行加标,在低、中、高3个加标水平下测得AOX的平均回收率为82.3%~98.7%,相对标准偏差(RSD,n=7)为2.0%~5.7%,表明方法具有良好的回收率和精密度。将该方法应用于实际纺织样品的测定,检出了不同含量的AOX,且重复性好。研究建立的方法通过采用活性炭的振荡吸附、程序升温的高温氧化燃烧方式和多孔吸收瓶的二级吸收方法,提高了AOX转化为无机卤素的回收率;同时利用离子色谱仪器选择性好、灵敏度高的特点成功地一次性分离检测4种AOX,且无杂质离子的干扰。该方法简单、准确、可靠,满足国内外法规和标准对纺织品中AOX的限量要求,适用于纺织品中AOX的分析测定。 相似文献
6.
Recombinant clones of X-33 strain Pichia pastoris containing the marker gene yEGFP were prepared. The optimal methanol concentration in the medium for induction of heterologous expression was determined in the recombinant clones.__________Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 60–62, January–February, 2005. 相似文献
7.
Expression of Recombinant Proteins in <Emphasis Type="Italic">Pichia Pastoris</Emphasis> 总被引:5,自引:0,他引:5
Li P Anumanthan A Gao XG Ilangovan K Suzara VV Düzgüneş N Renugopalakrishnan V 《Applied biochemistry and biotechnology》2007,142(2):105-124
Pichia pastoris has been used extensively and successfully to express recombinant proteins. In this review, we summarize the elements required
for expressing heterologous proteins, and discuss various factors in applying this system for protein expression. These elements
include vectors, host strains, heterologous gene integration into the genome, secretion factors, and the glycosylation profile.
In particular, we discuss and evaluate the recent progress in optimizing the fermentation process to improve the yield and
stability of expressed proteins. Optimization can be achieved by controlling the medium composition, pH, temperature, and
dissolved oxygen, as well as by methanol induction and feed mode. 相似文献
8.
Estefanía Costa Rama Julien Biscay María Begoña González García A. Julio Reviejo José Manuel Pingarrón Carrazón Agustín Costa García 《Analytica chimica acta》2012
Different very simple single-use alcohol enzyme sensors were developed using alcohol oxidase (AOX) from three different yeast, Hansenula sp., Pichia pastoris and Candida boidinii, and employing three different commercial mediator-based Screen-Printed Carbon Electrodes as transducers. The mediators tested, Prussian Blue, Ferrocyanide and Co-phthalocyanine were included into the ink of the working electrode. The procedure to obtain these sensors consists of the immobilization of the enzyme on the electrode surface by adsorption. For the immobilization, an AOX solution is deposited on the working electrode and left until dried (1 h) at room temperature. The best results were obtained with the biosensor using Screen-Printed Co-phthalocyanine/Carbon Electrode and AOX from Hansenula sp. The reduced cobalt–phthalocyanine form is amperometrically detected at +0.4 V (vs. Ag pseudo reference electrode). This sensor shows good sensitivity (1211 nA mM−1), high precision (2.1% RSD value for the slope value of the calibration plot) and wide linear response (0.05–1.00 mM) for ethanol determination. The sensor provides also accurate results for ethanol quantification in alcoholic drinks. 相似文献
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