Liquid Chromatographic Residue Analysis of Carbaryl Based on a Post-Column Catalytic Reactor Principle and Fluorigenic Labelling

Abstract

A method is described for the residue analysis of carbaryl in polluted water samples. The technique is based on catalytic hydrolysis of the carbaryl on anion exchangers followed by fluorescence detection of the α-naphthol or the OPA derivative of the methyl amine. A low cost 200 mesh Amberlite strong anion exchanger can be used for this purpose when coupled to the OPA reaction detector. Combining this approach with on-line preconcentration and clean-up on an 3P-18 loaded precolumn can provide a powerful tool for automated residue analysis of carbaryl (and other N-methyl carbamates) in polluted water sources. Recoveries in the order of 100% are reported. The reproducibility of the technique is better than 2% rel. st. dev. Detection limits are 0.4–2 ng per injection for carbaryl depending on the system and linearity of response is more than two orders of magnitude with r = 0.9998. The selectivity and sensitivity of this method permits residue analysis at the sub ppb concentration level in heavily polluted water samples. Data on hydrolysis yields and band broadening as a function of residence time and temperature in the reactor are given.     

一种简易的脑片图像的半自动区域划分及细胞计数方法

脑科学研究往往需要对实验动物不同脑区的分子表达、细胞数目及神经网络连接模式进行量化和比较分析,然而目前缺乏简便易行的规模化的脑区划分方法.本文基于Paxinos和Franklin的第二版小鼠图谱以及Photoshop和ImageJ等图像处理软件,发展了一种简易的脑片图像的半自动区域划分及细胞计数方法.首先,基于小鼠脑图谱可获得脑区划分所需的标准模版;然后,利用Photoshop软件对标准模版进行变形矫正,可实现小鼠脑切片图像的快速规模化半自动配准及区域分割;最后,利用ImageJ可实现对配准及分区后的脑片图像不同区域的半自动神经细胞计数和分析.此方法适用于脑片免疫组织化学分析、神经元分布模式检测和神经环路标记等研究,其操作简便、易于获取、并且不依赖于其他昂贵的商业化神经图像分析软件,能为条件有限的科研工作者提供极大便利.     

Split-root labelling to investigate 15N rhizodeposition by Pinus sylvestris and Picea abies*

We investigated the transfer of ¹⁵N into the soil via ¹⁵N uptake and release by tree roots, which involves the principles of the split-root technique. One half of the root system received an injection of (¹⁵NH₄)₂SO₄ and the other half equivalent amounts of (NH₄)₂SO₄ at ¹⁵N natural abundance level. ¹⁵N was transferred from one side of the root system (¹⁵N side) to the other side (¹⁴N side) and released into the soil. The method was conducted with Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies [L.] Karst). Two concentration levels of (NH₄)₂SO₄ were used, corresponding with annual N deposition in the Netherlands (30 kg N ha^–1) and a twelfth of that (2.5 kg N ha^?1). Samples were taken 3 and 6 weeks after labelling and divided into needles?+?stem, roots, rhizosphere and bulk soil. Already 3 weeks after labelling, Scots pine took up 23.7?% of the low and 9.1?% of the high amounts of ¹⁵N, while Norway spruce took up 21.5 and 32.1?%, respectively. Both species transported proportions of ¹⁵N to the rhizosphere (0.1–0.2?%) and bulk soil (0.3–0.9?%). The method is a useful tool to investigate the fate of root-derived N in soils, for example, for the formation of stable forms of soil organic matter.     

Chloramine-T as Labelling Agent for Oleic Acid and Olive Oil

Olive oil and its main constituent, oleic acid, have been labelled with ¹²⁵I using chloramine-T (CAT) as an oxidizing agent. The maximum yields of labelling in different organic solvents were found to vary between 10 to 50% for oleic acid. The values for olive oil were 70% of those of oleic acid. The labelled compounds were stable in allorganic solvents except for acetone where they start to decompose after 20 min of starting the experiments. The low yields could be attributed partly to a possible labelling of CAT or to the reaction of CAT with labelled compounds or their precursores.

Olivenöl und seind Hauptbestandteil, die Oleinsäure, wurde mit ¹²⁵I markiert, wobei Cloramin-T (GAT) als Oxidationsmittel verwendet wurde. Maximale Markieungs-Ausbeuten in verschiedenen organischen Lösungsmitteln variierten zwischen 10 … 50% an Ölsäure. Die Werte für Olivenöl waren 70% von der Oleinsäure. Die markierten Verbindungen waren in allen organischen LöSungsmitteln stabil mit Ausnahme von Aceton, in welchen bereits nach 20 Minuten eine Zersetzung zu beobachten war. Die niedrigen Ausbeuten könnten teilweise auf eine mögliche Markierung des CAT oder auf eine Reaktion des CAT mit den markierten Verbindungen oder ihren Vorstufen zur¨ckgeführt werden.     

Synthesis of Tritiated Components of Nucleic Acids Part 3

At the catalytic tritiation of 5-Formyluracil (5-FU), different compounds are generated. The kind of the species depends on the reaction conditions. 5-FU is one of the derivatives of uracil which are slightly approachable to a catalytic hydrogen isotope exchange. This isotope exchange in the formyl group seems to be favoured above the 6-position in the uracil ring, because of its greater reactivity. After separation of the impurities, we obtained tritiated 5-FU with a specific radioactivity of nearly 1480 GBq/mmol and a radiochemical purity >98%. The pressure of tritium gas was <25 kPa. The catalyst we used was PdO(1.4%)/BaSO₄. With the same catalyst we obtained 5-Hydroxymethyl[hydroxymethyl-³H]- uracil by raising the pressure of tritium gas to 50 kPa. Hydrogenation of the 5.6 double bond occurred by an additional raising of the pressure to 75 kPa and we obtained 5-Hydroxymethyldihydrouracil (5-DHMU) [1].     

钠分子2~3∏_g←X~1∑_g~＋双光子跃迁的研究

通过比较园偏振和线偏振两种激发方式下，钠分子的等频双光子跃迁谱线的强度变化和２３Ⅱｇ→α３∑＋ｕ辐射谱的数值拟合计算，对２３Ⅱｇ←Ｘ１∑＋ｇ的双光子跃迁进行了标识．     

Photodegradation of poly(ether sulphone) Part 2. Wavelength and atmosphere dependence

The photodegradation of poly(ether sulphone) (PES) was investigated systematically by time‐of‐flight SIMS (ToF‐SIMS) and x‐ray photoelectron spectroscopy (XPS). The effect of varying the irradiation dose, wavelength and the atmosphere was studied along with mechanistic photooxidation studies using ¹⁸O₂. Photoinduced ? SO₃H group formation was observed at 199, 260 and 315 nm for an oxygen‐containing atmosphere only. Photoinduced ? OH group formation is observed at all investigated wavelengths and atmospheres. Photoinduced cross‐linking was an important process in a vacuum. The oxygen reacts quickly with the PES surface during photoirradiation and chain scission was found to be the dominant process, and oxygen incorporation was found to be non‐specific but pronounced for ? SO₃H group formation. It was found that for conditions where processes are affected by photoirradiation the extent is observed to follow the UV absorption and showed little dependence on the wavelength. The wavelength only affects the extent of the process in question, which is ascribed to a fast equilibrium of the absorbed energy. The photoinduced processes are very sensitive towards the presence of the smallest amounts of oxygen in the atmosphere. Copyright © 2004 John Wiley & Sons, Ltd.     

Development of a microwave-enhanced isotopic labelling procedure based on the Eschweiler–Clarke methylation reaction

A number of primary and secondary amines have been rapidly methylated under microwave-enhanced conditions using formic acid-formaldehyde mixtures, providing a route to ²H(D)-containing compounds and the potential for ³H(T), ¹¹C, ¹³C and ¹⁴C labelling.     

Non‐Thermal Plasma in Contact with Water: The Origin of Species

Non‐thermal atmospheric pressure plasma has attracted considerable attention in recent years due to its potential for biomedical applications. Determining the mechanism of the formation of reactive species in liquid treated with plasma is thus of paramount importance for both fundamental and applied research. In this work, the origin of reactive species in plasma‐treated aqueous solutions was investigated by using spin‐trapping, hydrogen and oxygen isotopic labelling and electron paramagnetic resonance (EPR) spectroscopy. The species originating from molecules in the liquid phase and those introduced with the feed gas were differentiated by EPR and ¹H NMR analysis of liquid samples. The effects of water vapour and oxygen admixtures in the feed gas were investigated. All the reactive species detected in the liquid samples were shown to be formed largely in the plasma gas phase. It is suggested that hydrogen peroxide (determined by UV/Vis analysis) is formed primarily in the plasma tube, whereas the radical species ?OOH, ?OH and ?H are proposed to originate from the region between the plasma nozzle and the liquid sample.     

Isotopic labelling of peptides and isotope ratio analysis using LC–ICP–MS: a preliminary study

Bradykinin and substance P have been derivatised with cyclic diethylenetriaminepentaacetic anhydride (cDTPA) and subsequently labelled with natural and isotopically enriched Eu³⁺. This enabled the detection and relative quantitation of the peptides using element-selective detection by high-performance liquid chromatography inductively coupled plasma mass spectrometry (LC–ICP–MS). Relative quantitation was achieved by differentially labelling two peptide sources, after derivatisation with cDTPA, using natural and enriched ¹⁵¹Eu respectively. The ¹⁵¹Eu:¹⁵³Eu isotope ratio was measured and used to calculate the original peptide ratio. The measured ratios came within 5.2% of the known ratio. Derivatisation and chelation reactions were additionally confirmed using LC–ESI–MS.