有机氯农药质控用液体标准样品定值研究

研究了有机氯农药质控用标准样品的均匀性、稳定性和定值方法。本标准样品采用称量法制备,制备得到的标准样品通过了均匀性检验,且在30个月内是稳定的。其不确定度来源于多家实验室协作定值、均匀性和稳定性3个环节,并评定了各不确定度分量,其定值结果为:α-六六六为(10.8±1.0)μg/mL、β-六六六为(19.5±1.6)μg/mL、γ-六六六为(9.76±0.78)μg/mL、δ-六六六为(9.54±1.66)μg/mL、p,p'-DDE为(24.9±1.4)μg/mL、p,p'-DDD为(24.0±2.6)μg/mL、o,p'-DDT为(29.1±1.9)μg/mL、p,p'-DDT为(25.9±3.9)μg/mL。本标准样品制备浓度低,可用于环境监测工作中分析方法的验证、仪器性能的检定和分析技术人员的考核等。     

气相色谱质谱法测定土壤中6种有机氯农药

建立快速溶剂萃取-气相色谱质谱法测定土壤中七氯、艾氏剂、环氧七氯、狄氏剂、异狄氏剂和异狄氏剂酮的方法。6种有机氯农药在质量浓度5.00～250μg·L^-1范围内线性良好,检出限为0.001～0.004mg·kg^-1,三水平加标回收率范围为86.0%～105.5%,测试结果精密度范围为1.8%～4.8%(n=6)。该方法操作简单,测试准确,适用于土壤中痕量有机氯农药残留的监测。     

微量QuEChERS/气相色谱质谱法快速测定土壤中15种农药残留

为实现瓜菜种植土壤中常见农药的快速、灵敏测定,以改进的微量QuEChERS(μ-QuEChERS)辅助超声提取法,结合气相色谱质谱(GC-MS)分析,建立了土壤中15种农药残留的同时快速检测方法。土壤中15种农药残留采用含有V(1%乙酸的乙腈)∶V(二氯甲烷)=2∶1的混合溶液提取,上清液经过w(N-丙基乙二胺(PSA))∶w(C_(18))=3∶1混合吸附剂与无水Na_2SO_4净化。目标物在TG-5MS弱极性石英毛细管柱进行GC分离,以电子轰击电离源(EI)、选择离子监测(SIM)模式的外标法定量。结果表明,超过13种有机污染物在1.0～1 000μg/L范围内呈良好线性关系,且相关系数(r)均超过0.990。所建方法的检出限(LOD,S/N=3)为0.1～1.2μg/kg,定量限(LOQ,S/N=10)为0.5～4.3μg/kg。3个不同添加浓度(5.0、50、200μg/kg)的回收率在73.2%～114.5%范围内,相对标准偏差(RSD,n=3)在1.1%～11.4%范围内。将所建方法应用到海南南渡江流域瓜菜产区土壤中农药残留检测中,观察到土壤中均含有滴滴涕(DDT)、六六六(BHC),且均存在农药多残留情况(≥7种),其中联苯菊酯检测浓度最高。方法简单、快速且灵敏,有机试剂种类和用量少,适合土壤中15种常见农药多残留的同时、快速、批量检测。     

大气中有机氯类农药多残留的QuEChERS-气相色谱分析

采用大流量气体采样器采集大气样品,利用加速溶剂萃取仪萃取样品中的有机氯农药,用QuEChERS快速净化样品,气相色谱定量分析,结合气相色谱-质谱法进行确认。13种有机氯农药在10～200μg·L~(-1)浓度范围内线性关系良好,相关系数大于0.999,回收率为76.2%～102.6%,相对标准偏差在3.5%～14.3%(n=6),检出限为0.01～0.04ng·m~(-3)。实际样品分析结果表明,该方法能够满足HJ 901-2017的精密度要求,方法间相对偏差小于15%,且该方法快速、简便、灵敏度高、准确性好,可用于环境空气中有机氯农药残留的分析。     

快速溶剂萃取-气相色谱法测定土壤中六六六和滴滴涕残留

建立了快速溶剂萃取-气相色谱法测定土壤中α-HCH、β-HCH、γ-HCH、δ-HCH、p,p′-DDE、p,p′-DDD、o,p′-DDT、p,p′-DDT等8种有机氯农药残留的方法。8种有机氯农药标准曲线方程的相关系数均在0.9990以上;检出限为0.094-0.102μg·kg^-1;基质加标实验的回收率为84%-120%,相对标准偏差为3.06%-5.27%。该方法快速、定性和定量准确可靠,适合土壤中六六六和滴滴涕残留的分析测定。     

蔬菜中十六种农药残留的SIM-GC-MS分析

采用选择离子–气相色谱–质谱联用(SIM–GC–MS)方式,依据保留时间和特征离子丰度比,可以在30min之内检测有机磷(甲基对硫磷、甲拌磷、甲基异柳磷、马拉硫磷、毒死蜱、倍硫磷)、有机氯(敌敌畏、七氯、百菌清、α-六六六、γ-六六六、δ-六六六、p,p'-DDE、p,p'-DDD)、除虫菊酯(甲氰菊酯)、三唑酮等16种农药。通过优化色谱条件,可对16种农药同时进行定性和定量分析。建立了各种农药的标准曲线并计算回收率和最低检测限;标准曲线的线性关系良好,相关系数为0.997;平均回收率在75%～105%之间;检出限一般在8.8×10-4～2.6×10-3μg/g,基本上满足了多残留农药分析的要求。     

固相萃取-GC-ECD检测地表水中常见的5种有机氯农药

应用固相萃取-气相色谱质谱法建立测定地表水中常见的5种有机氯农药的方法。实验结果表明,在0.01~2.0μg/m L质量浓度范围内,5种有机氯农药线性关系良好,相关系数均不低于0.995;5种有机氯农药的检测限在0.001~0.01 mg/L之间。精密度(n=6)的RSD在2.3%~4.0%之间(n=6);加标回收率在84.1%~98.7%之间。实验表明,该方法样品处理简单、重现性好、精密度高,可用于地表水中中多种有机氯类农药残留的检测。     

气相色谱法测定白芍中31种农药的多残留分析方法

采用气相色谱-电子捕获监测器(Gc-ECD)、气相色谱一火焰光度检测器(GC-FPD)方法,建立了同时测定白芍中有机氯、有机磷等31种农药残留量的方法.结果表明:3个添加水平的平均回收率为72.18%～115.14%,相对标准偏差(RSD)均小于20%,最小检出限(LODs)为0.2～16_3 μg/kg,定量检出限(LOQs)为0.7～55.8μg/kg.     

气相色谱法测定贻贝中的多氯联苯和有机氯农药

建立了贻贝中多氯联苯和有机氯农药的超声提取固相萃取净化气相色谱检测方法,以正己烷-二氯甲烷作为溶剂进行超声提取,提取液经浓硫酸溶液和硅胶-弗罗里土固相萃取柱净化,再采用GC-ECD进行分析。本方法采用外标法进行定量分析,在2.5~100μg/L浓度范围内,相关系数r20.9951;多氯联苯和有机氯农药的检出限分别在0.01~0.04μg/kg和0.039~0.24μg/kg;各组分加标回收率在75%~115%之间(n=6),RSD15%。方法简便快速、重现性高,检测灵敏度和准确度均满足贻贝中多氯联苯和有机氯农药分析的要求。     

超高效液相色谱-串联质谱法同时测定土壤中46种禁限用农药

建立了同时测定土壤中46种禁限用农药的改进QuEChERS超高效液相色谱-串联质谱(UHPLC-MS/MS)方法。在最佳流动相组成下,46种禁限用农药检测灵敏度较高,结果可靠。质谱分析采用电喷雾电离,正负离子扫描、依赖保留时间的动态多反应监测模式(dMRM)下,以基质匹配内标法定量。结果表明,46种禁限用农药在各自的浓度范围内线性关系良好(R~20. 99); 3个添加水平(10、50、100μg/kg)下,46种禁限用农药的回收率为53%～129%,相对标准偏差(RSD,n=6)20. 0%,46种禁限用农药的定量限为1～20μg/kg,为土壤中准确、高效、经济的检测禁限用农药提供了可靠依据。     

PPH治疗混合痔的护理体会

目的探讨混合痔行PPH的护理方法。方法99例混合痔患者均行PPH,手术前向患者介绍住院环境、住院须知,告知治疗方法及护理上需要的配合,饮食、排便的注意事项,术前准备等;术后体位及恢复饮食时间,大小便情况观察及各种外用药的使用,出血护理及伤口护理,肛门功能锻炼;制定入院评估,印制出院指导。结果99例患者痔核明显回缩,顺利出院。结论混合痔PPH的术前术后护理对患者顺利康复有重要意义。     

Crosslinking of styrene-butadiene rubber with polyurethanes bicapped with benzyocyclobutene

Summary A polyurethane prepared from 1,9-nonanediol and toluene-2,4-diisocyanate with M_n=11,840, was capped on both ends in a reaction with 4-(benzocyclobutenyl) methanol. The polyurethane was used to crosslink styrene-butadiene rubber through Diels-Alder reactions on the benzocyclobutene functionality. The synthesis and characterization of 4-(benzocyclobutenyl) methanol, a molecule not reported previously, is presented. The crosslinking reaction was carried out on intimate mixtures of the telechelic polyurethane and SBR at elevated temperature and pressure. Various physical properties of the crosslinked material were studied.Work done at the Department of Chemistry, University of Akron, Akron, OH 44325, USA     

Copolymerization of acrylonitrile with maleamic acid derivatives and with carboxyphenylmaleimide

Acrylonitrile was copolymerized with two N-arylmaleamic acids and with N-3-carboxyphenylmaleimide in dimethylformamide (DMF) using azobisisobutyronitrile as initiator. The reactivity ratios and the Q-e parameters of these monomers were estimated, and the resulting copolymers were characterized by viscosity measurements and thermal analysis. Thermogravimetry and differential thermal analysis data showed an improvement in the thermal behaviour of the investigated copolymers compared with that of poly(acrylonitrile). Mechanisms illustrating the role of both the acidic group and the maleimide ring in the nitrile oligomerization were proposed. The produced copolymers showed an excellent affinity towards basic dyes and better color fastness towards UV light.     

Dehydrochlorination of propylene chlorohydrin with sodium hydroxide and with catholyte

Dehydrochlorination of an aqueous solution of propylene chlorohydrin with sodium hydroxide (12·5 and 30% by weight), with catholyte (5 or 10% by weight NaOH + 14% by weight NaCl) and with milk of lime (15% by weight) were compared. The use of catholyte (10% by weight NaOH + 14% by weight NaCl) enables propylene oxide to be obtained in a yield of 94·3%, with 100% conversion of chlorohydrin. The concentration of 1,2-propylene glycol in the waste is 0·07% by weight.     

Reaction of CH-acidic compounds with thiacumulenes and alkylation with dihaloalkanes

Dithiocarboxylation of CH-acidic compounds 1 and stepwise alkylation of primarily formed dithiolates 2 yielded ketene dithioacetals 5a,b or methylenebis(dithiocarbonates) 12a–c. Reaction of 5a,b with nucleophiles afforded thiophene 7 and dithioacetals 8, 9a,b, 11, respectively. 1,3-Thiazetidines 14a,c,e and thiazolidines 14b,d,f were prepared by thiocarbamoylation of 1b,c,e and subsequent alkylation with dihaloalkanes.     

复合扰流柱的螺旋内构件反应器内流体的宏观混合

在管式反应器内插入复合扰流柱的螺旋型内构件,采用脉冲示踪法测定了反应器内流体的停留时间分布,研究了器内流体的宏观混合特性,分析了该内构件强化混合的机理. 结果表明,复合扰流柱的螺旋型内构件反应器内的流体流动更接近于活塞流,其轴向扩散模型参数Pe为螺旋型内构件反应器的1.02~1.28倍,为不带内构件反应器的1.35~1.77倍. 复合扰流柱的螺旋型内构件能显著增强器内的二次流动,从而强化了宏观混合效果.     

Syntheses of bismaleimides with ester units and their polymerization with diamines

Five structurally different bismaleimides were synthesized by reaction between 3(4)‐maleimidobenzylchloride with various diphenols. They were characterized by infrared (IR) and proton nuclear magnetic resonance (¹H‐NMR) spectroscopy. Thermal characterization of monomers and their polymers was accomplished by differential scanning calorimetry (DSC) and dynamic thermogravimetric analysis (TGA). Polyaminobismaleimides having inherent viscosities of 0.1–0.4 dL/g were prepared by Michael addition of diamines to bismaleimides. The polymers are soluble in solvents as DMF, NMP, and DMSO, and afforded film from their solutions. © 2002 John Wiley & Sons, Inc. J Appl Polym Sci 84: 750–757, 2002; DOI 10.1002/app.10294     

AN-VA-MAS体系与AN-VA体系两种腈纶生产情况的对比

通过对聚合物和纤维的主要质量指标以及聚合釜生产能力变化的对比分析,说明了在腈纶生产中,使用AN-VA-MAS三元体系的聚合工艺优于AN-VA的二元体系聚合工艺.