反相高效液相色谱法同时测定土壤中莠去津,氰草津残留量方法研究

提出了用高效液相色谱法同时测定土壤中莠去津、氰草津残留量的方法。用甲醇／乙腈提取，石油醚脱脂，中性氧化铝小柱净化，最后用Ｎｏｖａ－ＰａｋＣ１６柱进行ＨＰＬＣ分析，流动相：甲醇－水（５５＋４５），吸收波长 ２２８ ｎｍ，流速０． ７ ｍＬ／ｍｉｎ．莠去津最低检出限为 ０．３ ｎｇ，氰草津为０．２ ｎｇ。回收率分别为莠去津８３．４％～１０２．３％，氰草津 ８２．４％～９３．５％．     

Increased sensitivity of an enzyme immunoassay (ELISA) for the determination of triazine herbicides by variation of tracer incubation time

Immunoassays for triazine herbicides were tested for their reaction to the variation of the tracer incubation time. By application of a sequential technique the measuring range of atrazine could be expanded to five decades and the total duration of the test could be reduced to about 30 min. In an optimized version a lower detection limit of 9 pmol/l (2 ng/l) was achieved. The detection limit of a sensitive immunoassay for terbuthylazine is also below the concentration limit demanded of the German drinking water regulation (100 ng/l) and reaches 130 pmol/l (30 ng/l). Short tracer incubation times did not lead to increased cross-reactivities in contrast to theoretical models [1, 2]. Different mechanisms, which could cause a shift of the center point of the calibration curve, are discussed, including kinetic considerations.Nomenclature ametryn 2-(ethylamino)-4-(isopropylamino)-6-(methylthio)-1,3,5-triazine - atrazine 2-(chloro)-4-(ethylamino)-6-(isopropylamino)-1,3,5-triazine - deethylatrazine 2-(amino)-4-(chloro)-6-(isopropylamino)-1,3,5-triazine - DMSO dimethylsulfoxide - DOC dissolved organic carbon - ELISA enzyme-linked immunosorbent assay - glyme 1,2-dimethoxyethane - hydroxyatrazine 2-(ethylamino)-4-(hydroxy)-6-(isopropylamino)-1,3,5-triazine - PBS phosphate buffered saline - propazine 2-(chloro)-4,6-bis(isopropylamino)-1,3,5-triazine - simazine 2-(chloro)-4,6-bis(ethylamino)-1,3,5-triazine - terbuthylazine 2-(tert-butylamino)-4-(chloro)-6-(ethylamino)-1,3,5-triazine - TLC thin-layer chromatography - TMB 3,3,5,5-tetramethylbenzidine - tracer enzyme (peroxidase) labeled hapten     

Atrazine and its degradation products in surface and ground waters in Zhangjiakou District, China

A method using the solid phase extraction (SPE) and liquid chromatography-mass spectrometry (LC-MS) to analyse atrazine and its degradation products at levels of low nanograms per liter in water has been developed. The environmental water samples were filtered and then extracted by SPE with a new sulfonation of poly(divinylbenzene-co-N- vinylpyrrolidone) sorbents MCX. HPLC/APCIMS was used for the analysis of atrazine and its degradation products, desethylatrazine (DEA), deisopropylatrazine (DIA), didealkylatrazine (DEDIA), and hydroxyatrazine (HYA). The detection limits ranged from 10-50 ng/L in water samples. Samples were collected from deep wells and a reservoir near a plant that produced atrazine. Atrazine concentration levels in most surface samples were above the limit of the China Surface Water Regulation (3 mg/L). In ground water, the levels of degradation product were more than 0.1 mg/L and 5-10 times greater than those of atrazine. The highest DEA concentration in the groundwater sample taken at the 130 m depth was 7.2 ug/L.     

The Adsorption of Herbicides and Pesticides on Clay Minerals and Soils. Part 2. Atrazine

The adsorption of atrazine and two model compounds,2-chloropyrimidine and 3-chloropyridine on clay minerals(bentonite, montmorillonite and kaolinite), organic matter (humic acid) and soil (with and without organic matter) has beenstudied using FT-infrared spectroscopy (IR), thermogravimetric analysis (TGA), high pressureliquid chromatography (HPLC) and X-ray diffraction (XRD).3-Chloropyridine, 2-chloropyrimidine and atrazine were adsorbedthrough hydrogen bonding on bentonite, montmorillonite, humic acid and soil. In addition tohydrogen bonding, protonation of 3-chloropyridine and atrazine was also observed.In the adsorption of 2-chloropyrimidine on bentonite and montmorillonitean ion exchange mechanism also occurred. No adsorption of 3-chloropyridine or 2-chloropyrimidine wasobserved on the kaolinite clay mineral.Both the clay minerals and organic matter of soil contribute tothe adsorption of organic compounds on soil but the clay minerals bentonite and montmorilloniteplay a major role in their adsorption on soil.     

Critical evaluation of a screening test for detection of herbicides by inhibiting photosynthesis of isolated chloroplasts

The possibility to determine herbicides in the aqueous environment by observation of inhibiting effects on the photosynthesis of isolated chloroplasts have been critically evaluated. The photosynthetical activities of freshly isolated chloroplasts from spinach (Spinacia oleracea L.) and peas (Pisum sativum L.) have been compared under well-defined conditions. The standard for the rate of photosynthesis was the oxygen evolution, which has been detected by a Clark-type electrode. The ratio between the oxygen production rate before and after a sample addition describes the chloroplast activity. In the presence of herbicides this ratio decreases. Increasing herbicide concentrations have been determined by a normalization procedure in semilogarithmic scales using a sigmoidal calibration plot.Photosynthesis inhibiting substances, both natural and anthropogenic, can be detected collectively. That is an advantage over enzyme immunoassays which can only detect single herbicides. Clearly disadvantageous are the insufficient detection limits (e.g. 8.9 g/l for atrazine, respectively 2.5 g/l for terbuthylazine) and therefore the necessary preconcentration.     

Preparation,Homogeneity and Stability of Polar Pesticides in Freeze-Dried Water Interlaboratory Exercise

Abstract

An interlaboratory exercise was carried out to improve the state of the art of some polar pesticide determination in water (atrazine, simazine, carbaryl, propanil, linuron, fenamiphos and permethrin). The preparation, the homogeneity and the stability of freeze-dried water samples containing the above pesticides was studied. The final concentration of each pesticide in water was in the 50–80 μg.^?1 range with a salt content of 2.5 g.l^?1 of NaCl. After the lyophilization the residue was reho-mogenised, filled into amber glass bottles and stored at -20 °C and +20 °C. Every three months, one sample was analysed to verify the stability of the residue.

All pesticides were determined by high performance liquid chromatography with diode-array detection (HPLC-DAD) except permethrin which was determined by gas chromatography with electron capture detection (GC-ECD).

The results obtained show that the atrazine, carbaryl, propanil, linuron and fenamiphos samples were homogeneously distributed, whereas simazine and permethrin were not. With respect to the stability over three months, all pesticides were stable at ?20 °C. Atrazine, simazine, carbaryl, propanil and linuron are also stable for the maximum storage time at +20 °C but the concentration of fenamiphos decreased by about 70% after one month.

The results obtained in the interlaboratory study by the participants were in good agreement for many of the pesticides.     

超高效液相色谱-串联质谱法快速测定地表水中联苯胺、苦味酸、甲萘威、阿特拉津和溴氰菊酯

建立了一种经简单过滤即可直接进样的超高效液相色谱-串联质谱（UPLC-MS/MS）分析方法,可快速测定地表水中联苯胺、苦味酸、甲萘威、阿特拉津和溴氰菊酯5种有机物的残留。样品经0.2 μ m针式滤头过滤除去颗粒性杂质后,进行UPLC-MS/MS分析,采用UPLC HSS T₃色谱柱,2 mmol/L乙酸铵甲醇溶液和2 mmol/L乙酸铵水溶液作为流动相进行梯度洗脱,电喷雾离子源电离,正、负离子切换多反应监测模式进行定性和定量分析。5种目标化合物分别在0.10~10.0 μ g/L或1.00~100 μ g/L范围内线性关系良好,相关系数为0.996~0.999,方法的检出限为0.01~0.22 μ g/L;高、中、低3个添加水平的回收率为81.4%~113%,相对标准偏差为0.84%~14.0%。利用该方法对杭州市部分河流和水库的地表水样品进行分析,其中阿特拉津和溴氰菊酯在部分水样中有阳性检出。结果表明,该方法简便快捷、灵敏准确,适用于地表水样品中联苯胺、苦味酸、甲萘威、阿特拉津和溴氰菊酯的快速测定。     

在线固相萃取-超高效液相色谱-串联质谱法快速测定地表水中超痕量阿特拉津

建立了在线固相萃取-超高效液相色谱-串联质谱（on line SPE-UPLC-MS/MS）测定地表水中超痕量阿特拉津的方法。样品经滤膜过滤,HLB Direct Connect HP在线固相萃取小柱富集纯化,甲醇溶液洗脱,以Acquity BEH 130为分析柱,串联质谱进行检测,外标法定量。阿特拉津在1.0~5000 ng/L范围内线性关系良好,相关系数（r）为0.9989;该方法检出限为0.2 ng/L,阿特拉津的回收率为83.0%~105.1%,相对标准偏差为1.6%~5.3%（n=7）,满足超痕量分析测试的要求。该法灵敏度高,分析速度快,对于保障水环境安全、及时提供污染信息、有效应对环境应急突发事件具有十分重要的意义。     

莠去津高效降解菌的筛选及鉴定

为克服传统降解菌筛选的局限性,采用全新的筛选方法从长期施用莠去津的土壤中分离筛选出1株高效莠去津降解菌,该菌株可利用莠去津作为氮源生长,降解率可达98.46%.对其最佳生长条件及影响因素的实验研究显示最佳条件为:温度30℃、pH7.0.经生理生化鉴定和16s序列比对分析,鉴定其为丁香假单胞菌.外加氮源可促进菌体的生长但不会完全抑制农药的降解.因此,该研究为降解菌的筛选方式提供了全新的思路并为污染环境修复奠定了坚实的基础.     

荧光光谱法研究莠去津与过氧化氢酶的相互作用

应用荧光光谱法研究了水溶液中除草剂莠去津与过氧化氢酶分子间的相互作用 .结果表明 ,除草剂对过氧化氢酶的荧光有较强的猝灭作用 ,且静态猝灭是引起 CAT荧光猝灭的主要原因 .从荧光猝灭结果求出除草剂和 CAT的结合常数及结合位点数分别为 K=1.35× 10 5L/mol,n=1.17.并依据能量转移机制 ,求出了莠去津和 CAT相互结合时 ,其给体 -受体间距 r为 0 .15 9nm.由此可见 ,莠去津与过氧化氢酶的相互结合作用以静态猝灭过程为主 ,且其猝灭机制是通过能量转移产生的 .推测出莠去津与CAT的 16位 Tyr发生结合作用 .