固相萃取-气相色谱-串联质谱法同时测定人体尿液中4种有机磷农药代谢物

建立了同时测定尿液中4种有机磷类农药代谢物的气相色谱/串联质谱分析方法.尿液样品以WCX固相萃取柱富集提取,乙酸乙酯-乙腈(70∶30,V/V)再萃取,浓缩干燥,甲苯溶解,N-叔丁基二甲基甲硅烷基-N-甲基三氟乙酰胺衍生化.采用HP-5MS色谱柱(30 m×0.25 mm×0.25 μm)程序升温分离,串联质谱多反应检测,内标法定量.通过比较尿样中代谢物在不同萃取溶剂、固相萃取柱及pH值洗脱液等条件下的回收率,优化了前处理方法.在0.2～ 200 μg/L范围内,4种代谢物峰面积与内标峰面积的比值与质量浓度的线性关系良好(R2≥0.992),方法检出限为0.083 ～0.667μg/L,定量限为0.2～2.0 μg/L,平均回收率为54.1％～68.6％,相对标准偏差均小于8.5％(n=6).本方法稳定、可靠,分析时间短,不需要使用大量有机溶剂,可同时处理大批量样品,适用于人群有机磷类农药暴露情况的评估.     

加速溶剂萃取-硅胶萃取净化-气相色谱/质谱法检测地表水中有机氯农药和多氯联苯

建立了加速溶剂萃取-硅胶固相萃取净化-气相色谱/质谱同时检测地表水中15种有机氯农药(OCPs)和82种多氯联苯(PCBs)的方法.对影响OCPs和PCBs回收率的主要因素进行优化,得出最优的萃取条件:3次静态萃取循环,100℃的萃取温度,丙酮/正己烷(1∶1,V/V)为萃取液,静态萃取10 min.在最优条件下,15种OCPs和82种PCBs在加标水溶液中的回收率分别为70.9％～130％和52.5％～89.1％.日内和日间相对标准偏差分别为1.7％～16.1％和2.4％ ～33.3％.OCPs和PCBs混合标样在10～ 800 μg/L范围内线性相关系数(R2)均大于0.995.OCPs和PCBs方法检测限分别为0.13 ～0.38 ng/L和0.10 ～0.32 ng/L.相比于传统萃取方法,本方法回收率高、萃取时间短、试剂用量少.应用本方法测得北京城区地表水中OCPs和PCBs的含量范围分别为n.d.～ 3.45 ng/L和n.d.～4.88 ng/L.     

“Turn-off” fluorescent data array sensor based on double quantum dots coupled with chemometrics for highly sensitive and selective detection of multicomponent pesticides

As a popular detection model, the fluorescence “turn-off” sensor based on quantum dots (QDs) has already been successfully employed in the detections of many materials, especially in the researches on the interactions between pesticides. However, the previous studies are mainly focused on simple single track or the comparison based on similar concentration of drugs. In this work, a new detection method based on the fluorescence “turn-off” model with water-soluble ZnCdSe and CdSe QDs simultaneously as the fluorescent probes is established to detect various pesticides. The fluorescence of the two QDs can be quenched by different pesticides with varying degrees, which leads to the differences in positions and intensities of two peaks. By combining with chemometrics methods, all the pesticides can be qualitative and quantitative respectively even in real samples with the limit of detection was 2 × 10⁻⁸ mol L⁻¹ and a recognition rate of 100%. This work is, to the best of our knowledge, the first report on the detection of pesticides based on the fluorescence quenching phenomenon of double quantum dots combined with chemometrics methods. What's more, the excellent selectivity of the system has been verified in different mediums such as mixed ion disruption, waste water, tea and water extraction liquid drugs.     

羟基化多壁碳纳米管分散固相萃取/气相色谱-质谱测定茶叶中有机氯农药和拟除虫菊酯类农药残留

建立了羟基化多壁碳纳米管作为吸附剂的改进Qu ECh ERS方法,联合气相色谱-质谱联用法快速检测茶叶中24种有机氯农药和拟除虫菊酯类农药残留量。茶叶样品中的农药残留经正己烷-丙酮(2∶1)提取,以羟基化多壁碳纳米管(MWCNTs-OH)和N-丙基乙二胺键合固相吸附剂(PSA)吸附提取液中的杂质,提取液离心后过滤,经气相色谱-电子轰击源质谱法测定,外标法定量。研究了不同吸附剂种类、提取溶剂、吸附剂用量对提取净化效率的影响。在优化实验条件下,目标物质在0.01~0.50 mg/kg范围内线性关系良好。空白茶叶样品在低、中、高3个加标水平下的平均回收率为78.6%~109.6%,相对标准偏差(n=5)为2.1%~9.3%;方法的定量下限为0.002~0.050 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氯和拟除虫菊酯类农药残留的检测要求,特别适合在小型实验室和企业中推广使用。     

Simultaneous preconcentration of polar and non‐polar organophosphorus pesticides from water samples by using a new sorbent based on mesoporous silica

A new mesoporous silica based on the sol–gel material cyanopropyltriethoxysilane (CNPrTEOS) was successfully synthesized by the hydrolysis and condensation of CNPrTEOS in the presence of ammonium solution as catalyst and methanol as solvent. It was used as a solid‐phase extraction sorbent for the simultaneous extraction of three organophosphorus pesticides, namely, polar dicrotophos and non‐polar diazinon and chlorpyrifos. Analysis was performed using high‐performance liquid chromatography with UV detection. CNPrTEOS was characterized by FTIR spectroscopy, field‐emission scanning electron microscopy and nitrogen gas adsorption. The surface area and average pore diameter of the optimum sol–gel CNPrTEOS are 379 m²/g and 4.7 nm (mesoporous), respectively. The proposed solid‐phase extraction based on CNPrTEOS exhibited good linearity in the range of 0.8–100 μg/L, satisfactory precision (1.15–3.82%), high enrichment factor (800) and low limit of detection (0.072–0.091 μg/L). The limits of detection obtained using the proposed solid‐phase extraction method are well below the maximum residue limit set by European Union and are also lower (13.6–48.5×) than that obtained by using a commercial CN‐SPE cartridge (0.98–4.41 μg/L). The new mesoporous sol–gel CNPrTEOS showed promising alternative as SPE sorbent material for the simultaneous extraction of polar and non‐polar organophosphorus pesticides.     

Response surface methodology for the microwave-assisted extraction of insecticides from soil samples

The extraction of two pyrethroid insecticides (deltamethrin and α-cypermethrin) together with three organophosphorus insecticides (dimethoate, diazinon and malathion) from soil samples was carried out with microwave-assisted technology. Experimental designs showed that extraction temperature, addition of water to the extractant and solvent/soil ratio were the variables that affected the recoveries of the pesticide the most. Response surface methodology was applied to find the optimum values of the variables involved in the extractions of the analytes. In addition, in order to achieve near-optimal extraction conditions, a desirability function was used to optimize the five pesticides simultaneously. The optimized conditions were applied to different types of soils.     

Determination of poorly fluorescent carbamate pesticides in water, bendiocarb and promecarb, using cyclodextrin nanocavities and related media

The effect of native cyclodextrins (alpha, beta, or gammaCD with six, seven and eight glucose units, respectively), hydroxypropyl-beta-cyclodextrin (HPCD), chitosan (CHT) and glucose in water solution or water with n-propylamine (PA) as co-solvent upon the UV-vis and fluorescence properties of poorly fluorescent N-methyl carbamates pesticides (C) as bendiocarb (2,2-dimethyl-1,3-benzodioxol-4-ol methylcarbamate, BC) and promecarb (3-methyl-5-(1-methylethyl)phenol methylcarbame, PC) was examined. Fluorescent enhancement was found for both substrates with all CDs in water or PA-water except from PC with alphaCD. The addition of CHT increases the fluorescence of BC but decreases the fluorescence of PC, and glucose addition gives in both cases no spectral changes. Host-guest interaction was clearly determined by fluorescence enhancement with betaCD and HPCD with a 1:1 stoichiometry for the complexes (C:CD). The values obtained for the association constants (K(A), M(-1)) were (6+/-2)x10(2) and (2.3+/-0.3)x10(2) for BC:betaCD and BC:HPCD complexes, respectively. For PC:betaCD and PC:HPCD the values of K(A) were (19+/-2)x10(2) and (21+/-2)x10(2), respectively. The ratio of the fluorescence quantum yields for the bound and free substrates (phi(CCD)/phi(C)) was in the range 1.74-3.8. The limits of detection (L(D), microg mL(-1)) for the best conditions were (0.57+/-0.02) for BC with HPCD and (0.091+/-0.002) for PC with betaCD in water. Application to the analysis in pesticide spiked samples of tap water and fruit yields satisfactory apparent recoveries (84-114%), and for the extraction procedure in fruits and a commercial formulation, recoveries were of 81-98% and 104%, respectively. The method is rapid, simple, direct, sensitive and useful for pesticide analysis.     

加速溶剂萃取-固相萃取净化-气相色谱-串联质谱法检测茶叶中9种拟除虫菊酯类农药残留

建立了加速溶剂萃取（ASE）-固相萃取净化（SPE）-气相色谱-串联质谱（GC-MS/MS）同时测定茶叶中9种拟除虫菊酯类农药残留的方法。ASE萃取溶剂为丙酮-正己烷（1：1,v/v）,萃取温度为100℃,萃取压力为10 MPa,加热时间为3 min,静态萃取时间为5 min,循环1次,冲洗体积为40%萃取池体积,氮气吹扫100 s。萃取结束后用Cleanert TPT固相萃取柱净化,净化液浓缩定容后,采用GC-MS/MS测定,外标法定量。9种拟除虫菊酯类农药在2~1000 μg/L范围内呈现良好的线性关系,相关系数（r²）均大于0.99,方法检出限为0.2~4.5 μg/kg,定量限为0.8~15.0 μg/kg。在绿茶、红茶空白基质中做加标回收试验,添加水平为0.02、0.1、0.4 mg/kg以及定量限水平,得到的平均回收率为69.87%~110.0%,相对标准偏差（RSD）为0.7%~11.2%。该方法背景干扰低、灵敏度高、重现性好、回收率稳定,适用于茶叶中拟除虫菊酯类农药残留量的检测。     

超高效液相色谱-串联质谱法测定蜂蜜中抗生素和农药浓度

基于快速有效的基质净化方法,结合超高效液相色谱-串联质谱技术,建立了测定蜂蜜中39种抗生素及25种农药的检测方法.蜂蜜样品经乙腈+水（v/v=8：2）提取,用PRiME HLB净化,超高效液相色谱-串联质谱（ultra-performance liquid chromatography tandem mass spectrometry,UPLC-MS/MS）分析测定,通过多反应监测模式（MRM）分析目标化合物,并进行基质标准曲线定量.在测定浓度范围内呈良好线性关系,相关系数大于0.99;农兽药的检出限为0.02~3.8 μg·kg^-1,定量限为0.1~11.5 μg·kg^-1;在3档浓度的添加回收实验中,39种抗生素的回收率在72%~119%内,25种农药的回收率在72%~115%内,相对标准偏差均小于15%.随机抽取浙江市场上在售的52份蜂蜜样进行检测分析和膳食暴露评估,共检出罗红霉素、诺氟沙星和环丙沙星3种抗生素,检出率分别为2.6%,8.6%和3.9%,浓度分别为59.6~214.4,4.7~1 486.3和5.9~215.1 μg·kg^-1.膳食暴露评估结果表明,蜂蜜中抗生素残留对10岁以下组群的风险高于其他组群、女性消费者高于男性消费者;% ADI<100,说明膳食暴露评估风险水平尚可接受.因在计算中存在诸多不确定性因素,对组群的风险评估尚需进一步分析.     

Fe3O4纳米粒子修饰多壁碳纳米管的制备及在水和蜂蜜样品中痕量菊酯类农药分析中的应用

通过化学共沉淀法使Fe₃O₄纳米粒子负载于酸化多壁碳纳米管(AMWNTs)表面,得到Fe₃O₄/AMWNTs磁性纳米材料。该材料具有很好的磁响应度和分散性,将其用于富集痕量拟除虫菊酯类农药残留,结果证明该复合材料对菊酯类农药的吸附性能良好。通过对影响萃取性能的几种因素如离子强度、萃取时间和解吸时间依次进行优化,在最优条件下,建立了Fe₃O₄/AMWNTs磁性分散固相萃取-气相色谱测定6种菊酯类农药残留的分析方法。线性范围在0.5~50 μg/L之间,相关系数(R²)大于0.990,检出限为0.07~0.20 μg/L,精密度为3.8%~8.1%。该方法用于河水、鱼塘水和两种市售蜂蜜中菊酯类农药的残留分析,回收率高于78.4%。该方法操作简便、灵敏度高,能够满足环境水样及蜂蜜样品中痕量菊酯农药残留的分析需求。