Application of Nylon6/Polypyrrole core–shell nanofibres mat as solid-phase extraction adsorbent for the determination of atrazine in environmental water samples

A novel solid-phase extraction (SPE) system, based on a new sorbent of Nylon6/Polypyrrole (PA6/PPy) core–shell nanofibres mat and a new packing format of SPE disks, is presented in this paper. A series of related parameters that may affect the efficiency, such as the kind of eluent and its volume, the amount of nanofibres mat, ionic strength, pH of the sample, flow rate of the sample and volume of the sample, have been investigated systematically. Under the optimised conditions, the target analyte in 10 mL water samples can be completely extracted by a 3.0 mg PA6/PPy nanofibres mat and easily eluted by 400 µL acetonitrile. Around 20 µL elution was injected directly to HPLC-UV for determination, without further concentration. Besides, the nanofibres mat could be repeatedly used up to six cycles. Satisfactory linearity was achieved in the range of 0.1–40.0 ng/mL with a correlation coefficient of 0.9999. The limit of detection (LOD) (3 S/N) was 0.03 ng/mL, which could meet the determination requirements of atrazine as per the European Union legislation, US. Safe Drinking Water Act and the State Environmental Protection Administration of China. The simple, effective and economic method was proposed for the determination of atrazine in environmental water at trace level. The recoveries ranged from 94.73 to 114.92%, with relative standard deviations (RSDs) of 2.5–4.2%, and were obtained from tap water and lake water samples with atrazine at 2.0 ng/mL, suggesting the actual feasibility of the proposed method in environmental water samples.     

气相色谱法分析尿液样品中的阿特拉津及其代谢物

建立了尿液样品中阿特拉津(ATZ)及其代谢物脱乙基阿特拉津(DEA)、脱异丙基阿特拉津(DIA)、脱乙基脱异丙基阿特拉津(DEDIA)的气相色谱分析方法。样品经乙酸乙酯萃取、硫酸钠脱水、弗罗里硅土净化、浓缩后用气相色谱-电子俘获检测器分析。对样品萃取时的pH值等条件进行了优化,获得了较好的回收率。方法的检出限分别为DEDIA 0.0025 mg/L,DEA、DIA、ATZ 0.005 mg/L。4种化合物在进样量为0.2~8 ng时与其峰面积呈良好的线性关系。利用该方法对阿特拉津生产厂工人的尿液样品进行了分析,尿液中4种化合物的质量浓度为：DEDIA 0.003～0.301 mg/L,DEA 0.005～0.011 mg/L,DIA 0.006～0.276 mg/L,ATZ 0.005～0.012 mg/L。     

莠去津分子印迹聚合物的合成及其吸附性能

以莠去津(1)为模板分子,甲基丙烯酸(MAA)为功能单体,乙二醇二甲基丙烯酸酯(EDMA)为交联剂,在偶氮二异丁腈(AIBN)的引发下,于65℃聚合17 h合成了对1有特异识别性能的分子印迹聚合物(2)。用紫外分光光度法探索了1与MAA的最佳比例,研究了2的吸附性能力,并利用高效液相色谱法对2的选择性进行了考察。用Scatchard法分析表明,2通过氢键作用力结合,存在两种结合位点,对1的吸附存在两种形态,最大表观吸附量(Qmax,1)为130.9 nmol.g-1,平衡离解常数(Kd,1)为30.8 nmol.L-1,Qmax,2为540.5 nmol.g-1,Kd,2为450.5 nmol.L-1。与西玛津相比,2对1显示出一定的选择性。以2作为填料制备出具有莠去津分子印迹的固相萃取柱,可对水质中2×10-8mol.L-1以下的待测物进行富集和分离,回收率近90%。     

棕壤不同粒径组分对阿特拉津吸附-解吸作用的影响

采用批平衡实验,研究阿特拉津在棕壤不同粒径组分上的吸附-解吸行为.结果表明,阿特拉津在不同粒径组分上的Kf值从大到小顺序为:5～10 μm≈2～5 μm≈<2μm>10～50 μm>50～250 μm.其中,当粒径为<2,2～5和5～10 μm,其吸附作用与土壤颗粒的有机质含量和游离氧化铁铝的量无明显相关性,这种现象可能与土壤有机质的组分、结构特征及有机质与矿物结合的方式有关.阿特拉津在不同粒径组分上的解吸作用均存在不同程度的滞后作用,且均为正滞后现象.其中,尤以在5～10μm粒径上的滞后现象最明显.     

阿特拉津农药在包气带内运移模拟

对植物根区(土壤层)及渗流区(作物根区以下潜水面以上包气带部分)农药的行为进行了数学描述．应用植物根区数学模型模拟了旱田除草剂阿特拉津农药在研究区包气带中的行为．模拟结果表明,吸附系数较小、降解半衰期较长和在水中的溶解度较大的阿特拉津农药可长期残留在包气带内,并且能够随降雨入渗进入潜水含水层而污染地下水．     

零价铁活化过二硫酸盐氧化降解阿特拉津

利用零价铁(Fe0)活化过二硫酸钠(PDS)产生硫酸根自由基(SO4-.)降解环境中的阿特拉津。初步探讨了介质初始pH值、PDS初始浓度、Fe0加入量对阿特拉津降解率的影响,并比较了铁量相同的Fe0/PDS、Fe2+/PDS和Fe3+/PDS 3种体系对阿特拉津的降解能力。结果表明,在初始pH=6.5、1 mL初始浓度为2.0 mmol/L PDS、Fe0加入量为28 mg的条件下,反应60 min后,Fe0/PDS体系对100 mL浓度为0.10 mmol/L阿特拉津的降解率达到99.0%,远高于Fe0、PDS、Fe2+/PDS和Fe3+/PDS 4种体系对阿特拉津的降解率。另外,酸性介质、增加Fe0或PDS的投入量均有利于提高阿特拉津的降解率。同时,通过采用甲醇和叔丁醇作为分子探针鉴定了Fe0/PDS体系中产生的活性中间体SO4-.和羟基自由基(.OH)。     

Immobilization of atrazine on gold,a first step towards the elaboration of an indirect immunosensor: characterization by XPS and PM‐IRRAS

As part of our long‐term goal to design a novel type of immunosensor based on IR transduction, we devised two strategies to immobilize derivatives of the herbicide atrazine on the surface of planar gold substrates. Both strategies take advantage of the well‐known formation of self‐assembled monolayers of thiolates via spontaneous chemisorption of thiols or disulphides on noble metal surfaces. The first strategy involved the direct chemisorption of a disulphide derivative of atrazine, while the second strategy was based on the covalent attachment of a polymer tethered with atrazine derivatives to a previously adsorbed thiolate carrying a carboxylic acid head group. The resulting organic thin films on gold were characterized by polarization modulation infrared reflection‐absorption spectroscopy (PM‐IRRAS) and XPS. The binding of a polyclonal anti‐atrazine antibody to both sensing layers was also tested and compared. It appeared that specific molecular recognition occurred only on the atrazine disulphide sensing layer. Copyright © 2006 John Wiley & Sons, Ltd.     

Immunoaffinity Chromatography of s-Triazines

Abstract

Immunoaffinity chromatography (IAC) provides a selective method for sample preparation prior to high-performance liquid chromatography (HPLC) or gas chromatography (GC). Five different support materials were tested for their suitability with regard to IAC of herbicides (s-triazines). Three gels showing low (0-10 %) nonspecific s-triazine adsorption were used as affinity supports (Beaded cellulose ONB-carbonate A, LiChroprep hydrazide tentacle gel and LiChroprep azlactone gel). A monoclonal antibody (K4E7), directed against atrazine, was covalently coupled to the gels. High antibody immobilization rates (100 %) were obtained with the beaded cellulose gel in comparison to the other gels (60-70 %). Subsequently the IAC columns were loaded with triazine solutions. Glycine-HCl 0.2 mol/L, pH 2.2 yielded the best results for the elution of the bound triazines from the beaded cellulose IAC columns (70-100 %). Both the hydrazide tentacle and the azlactone IAC columns showed lower elution rates (60-80 %).     

Capillary zone electrophoretic determination of hydroxymetabolites of atrazine in potable water using solid-phase extraction with Amberchrom resins

A CZE-separation system for hydroxyatrazine, desisopropylhydroxyatrazine, desethylhydroxyatrazine and ammeline is presented that allows their determination in environmental waters in the subgL^–1 domain after solid-phase extraction/enrichment with styrene-divinylbenzene and methacrylate macroporous (Amberchrom) resins. The CZE separation and determination system uses the stacking effect and an increased light path for UV-detection (bubble cell). The etching of the bubble cell was done in our laboratory. A ruggedness check of the CZE-system revealed the resolution of theN-dealkylated metabolites to be sensitive to pH, temperature and current variations as well as to changes of capillary dimensions. Fine-tuning of the separation is performed by variation of the current intensity in the constant-current mode. Recoveries from fortified tap-water samples were 95% for hydroxyatrazine, 70% for desethylhydroxyatrazine and approximately 20% for desisopropylhydroxyatrazine at the 0.2 g L^–1 concentration level. Due to its high polarity, ammeline is only slightly adsorbed on Amberchrom resins and cannot be enriched using these materials.     

Comparison of the Enrichment Efficiency of Multiwalled Carbon Nanotubes, C18 Silica, and Activated Carbon as the Adsorbents for the Solid Phase Extraction of Atrazine and Simazine in Water Samples

Multiwalled carbon nanotubes with exceptional merits as SPE adsorbents for enrichment of environmental pollutants have absorbed much attention. The goal of this paper was to make a comparison with it and regular adsorbents such as C18 silica and activated carbon in the extraction capacity of atrazine and simazine. The results indicated that multiwalled carbon nanotubes were very suitable for determination of atrazine and simazine because of an enrichment performance similar to that of C18 silica. In contrast, the spiked recovery of simazine was higher than that of atrazine using multiwalled carbon nanotubes as packing material for SPE. However, reverse results were obtained when the extraction was performed with packing of C18 silica. Moreover, as the extraction of simazine was concerned, multiwalled carbon nanotubes were much better than C18 silica. As for the enrichment of atrazine, C18 silica achieved greater extraction factor than multiwalled carbon nanotubes. Activated carbon did not give the expected extraction efficiency because of its large size and blank volume and less active sites for adsorption. All these experimental results indicated that multiwalled carbon nanotubes could be used as a valuable alternative adsorbent for SPE of atrazine and simazine in many real water samples.