分散固相萃取-液相色谱-质谱检测蔬菜水果中氨基甲酸酯和有机磷农药

以乙二胺-N-丙基硅烷(PSA)为吸附剂,乙腈为萃取溶剂,建立新型的基质分散固相萃取农残样品前处理技术,实现样品快速制备;利用LC-MS同时定量蔬菜和水果中的氨基甲酸酯和有机磷农药,并与常用固相萃取吸附剂ODS进行对比。选取4种代表性的蔬菜和水果,采用加标回收的方法,测定回收率和精密度,检验该方法的准确性和可靠性。对于绝大多数农药,在不同基质中,回收率为80%~110%,精密度为0.3%~8.0%。以西红柿为基质,检出限可达0.5~35μg/kg。研究表明,本方法法简单、快速、经济并具有较高灵敏度。采用本方法可对当地市场上常见时令蔬菜及水果进行监测。     

Biodegradation and bioaccumulation of fenitrothion in rat liver

The biodegradation of fenitrothion O,O-dimethyl-O-(3-methyl-4-nitro phenyl) phosphorothioate was investigated in rat liver after administration of various doses (5 mg/100 g body weight and 20 mg/100 g body weight) in acute treatment and 1 mg/100 g body weight in chronic treatment. High performance liquid chromatography of the pesticide and its metabolites formed in liver in acute treatment showed time-dependent sequential conversion of pesticide into three major metabolites within 24 h. These metabolites were separated and purified to homogenity by HPLC and characterized by IR spectroscopy as O,O-dimethyl-O-(3-methyl-4-amino phenyl) phsophorothioate (metabolite 1), O,O-dimethyl phosphorothioate (metabolite II) and O,O-dimethyl phosphate (metabolite III) in the fi rst dose (5 mg/100 g body weight). Metabolite II was found to be different in the second dose (20 mg/100 g body weight) and identified as O,O-dimethyl O-3-methyl-4-amino phenyl phosphate. The results with the fi rst dose indicated reduction of the nitro group in fenitrothion as step I followed by hydrolytic clevage of the P-O-aryl bond in metabolite I and oxidative desulphurylation of metabolite II. At higher dose (20 mg/100 g body weight) oxidative desulphurylation takes place as step II followed by hydrolysis of metabolite II. The bioaccumulation of fenitrothion within 60 days during chronic treatment showed no metabolite but continuous reduction in fenitrothion concentration, indicating excretion of pesticide and its products in urine and in faeces.     

Imprinted Polymer – Modified Hanging Mercury Drop Electrode for Differential Pulse Adsorptive Stripping Voltammetric Analysis of a Diquat Herbicide

An imprinted polymer modified hanging mercury drop electrode (HMDE) in Model 303A system in conjunction with a PAR Model 264A Polarographic Analyzer/Stripping Voltammeter has been used for the selective analysis of a diquat herbicide viz., 5,6‐dihydropyrazino[1,2,3,4‐[lmn]‐1,10‐phenanthrolinium dichlorides in differential pulse cathodic stripping voltammetry mode. Complex aqueous samples (drinking water and agricultural soil suspension), spiked with a diquat herbicide, were directly analyzed by the adsorptive accumulation of the analyte over the working electrode (accumulation potential ?0.8 V (vs. Ag/AgCl), accumulation time 120 s, pH 7.0, supporting electrolyte 0.1 M KCl, scan rate 10 mV s^?1, pulse amplitude 25 mV). The limit of detection for diquat herbicide was found to be 0.34 nmol L^?1 (0.1 ppb, RSD 2%, S/N=2).     

Simultaneous HPLC determination of phenylurea herbicides and their corresponding anilines in water after on-line preconcentration

On-line preconcentration on a short C₁₈ column, prior to HPLC with UV and electrochemical detection, has been used for determination of some phenylurea herbicides and their possible degradation products, substituted anilines, in water samples. With electrochemical detection the detection limit at a signal-to-noise ratio of 3 was 5 ppt for 4-chloroaniline and 4-bromoaniline and 7 ppt for 3,4-dichloroaniline; with UV detection the detection limit was ca 300 ppt for all analytes.     

苯基脲类除草剂分子印迹聚合物的合成和识别性能研究

以N-(4-异丙基苯基)-N′-亚丁基脲为模板, 甲基丙烯酸为功能单体, 乙二醇二甲基丙烯酸酯为交联剂制备了分子印迹聚合物(MIP). 研究了MIP对苯基脲类除草剂的亲和性和选择性. 在二氯甲烷流动相中制备的MIP对异丙隆(IP)、 非草隆(FN)、 甲氧隆(MX)、 敌草隆(DU)、 绿麦隆(CT)、 枯莠隆(DF)、 灭草隆(MN)、 草不隆(NB)、 播土隆(BT)和伏草隆(FU)等除草剂呈现出较高的亲和性, 而非印迹聚合物(NIP)对文中所用的14种苯基脲类除草剂均表现出非常低的保留或几乎没有保留. 实验及Mulliken电荷计算的结果显示， 苯基脲除草剂分子中的N′原子是主要的识别位点.     

Microwaves as “Co-Catalysts” or as Substitute for Catalysts in Organophosphorus Chemistry

The purpose of this review is to summarize the importance of microwave (MW) irradiation as a kind of catalyst in organophosphorus chemistry. Slow or reluctant reactions, such as the Diels-Alder cycloaddition or an inverse-Wittig type reaction, may be performed efficiently under MW irradiation. The direct esterification of phosphinic and phosphonic acids, which is practically impossible on conventional heating, may be realized under MW conditions. Ionic liquid additives may promote further esterifications. The opposite reaction, the hydrolysis of P-esters, has also relevance among the MW-assisted transformations. A typical case is when the catalysts are substituted by MWs, which is exemplified by the reduction of phosphine oxides, and by the Kabachnik–Fields condensation affording α-aminophosphonic derivatives. Finally, the Hirao P–C coupling reaction may serve as an example, when the catalyst may be simplified under MW conditions. All of the examples discussed fulfill the expectations of green chemistry.     

Rapid and Scalable Access to Sequence‐Controlled DHDM Multiblock Copolymers by FLP Polymerization

An immortal N‐(diphenylphosphanyl)‐1,3‐diisopropyl‐4,5‐dimethyl‐1,3‐dihydro‐2H‐imidazol‐2‐imine/diisobutyl (2,6‐di‐tert‐butyl‐4‐methylphenoxy) aluminum (P(NIⁱPr)Ph₂/(BHT)AlⁱBu₂)‐based frustrated Lewis pair (FLP) polymerization strategy is presented for rapid and scalable synthesis of the sequence‐controlled multiblock copolymers at room temperature. Without addition of extra initiator or catalyst and complex synthetic procedure, this method enabled a tripentacontablock copolymer (n=53, k=4, dp_n=50) to be achieved with the highest reported block number (n=53) and molecular weight (M_n=310 kg mol^?1) within 30 min. More importantly, this FLP polymerization strategy provided access to the multiblock copolymers with tailored properties by precisely adjusting the monomer sequence and block numbers.     

The Impact of Microwaves on Organophosphorus Chemistry

A personal account on the pioneering results on microwave (MW)‐assisted organophosphorus syntheses obtained in the last decade is presented. The broad spectrum of the reactions studied exemplifies the advantages of the MW technique as a green tool regarding efficiency and the simplification of catalyst systems. Theoretical calculations for a few typical models helped us to explore the scope and limitations of the application of MW irradiation.     

羟基化多壁碳纳米管分散固相萃取-气相色谱-质谱法测定茶叶中21种有机磷农药

建立了用羟基化多壁碳纳米管(MWCNTs-OH)、N-丙基乙二胺键合固相吸附剂(PSA)和MgSO₄作为吸附剂的改进QuEChERS-气相色谱-质谱快速检测茶叶中21种有机磷农药的方法。茶叶中残留的农药经正己烷-丙酮(2 : 1, v/v)混合溶剂提取,以MWCNTs-OH、PSA和MgSO₄去除杂质,离心、过滤后经气相色谱-电子轰击源质谱测定,外标法定量。结果表明,目标化合物在0.01~0.50 mg/kg范围内的线性关系良好。空白茶叶样品在低、中、高3个添加水平下的平均回收率为81.5%~109.4%,相对标准偏差(n=5)为2.3%~10.6%,定量限为0.001~0.040 mg/kg。该方法操作简单、快速、灵敏、成本低,能满足茶叶中常见有机磷农药残留的检测要求。     

有机磷酸酯阻燃剂污染现状与研究进展*

近年来,溴代阻燃剂在世界范围逐步禁用,作为其主要替代产品的有机磷酸酯类阻燃剂的生产与使用均有大幅度增长。因此,有机磷酸酯类物质也被引入环境中,由此所引起的环境问题也逐步引起了环境科学工作者的关注,成为新型有机污染物研究的又一个热点。本文综述了有机磷酸酯类阻燃剂的研究现状,包括有机磷酸酯类物质的污染现状、毒性以及分析方法,希望对我国开展该类物质的环境研究提供借鉴。