磁性氧化石墨烯固相萃取/高效液相色谱-串联质谱法测定环境水样中6种三嗪类除草剂残留

采用一步合成法制备磁性氧化石墨烯材料(GO-Fe_3O_4),将其用作磁性固相吸附剂对环境水样中的6种三嗪类除草剂进行萃取和富集,并与高效液相色谱-串联质谱法相结合进行测定。以扫描电镜和傅立叶红外光谱对合成材料进行了表征,并考察了GO-Fe_3O_4用量、萃取时间、水样的pH值及离子强度和解吸条件等因素对萃取效率的影响。6种三嗪类除草剂的检出限为0.1~1.0 ng/L,富集倍数可达616~902倍。将方法应用于苏州地区太湖水、运河水和护城河水等实际水样的分析,加标回收率为85.4%~117.6%,相对标准偏差为1.2%~10.0%。该方法操作简单快速,富集倍数较高,检出限低,可用于水样中痕量三嗪类除草剂残留的检测。     

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。     

磁性石墨烯固相萃取-分散液液微萃取-气相色谱法测定水和绿茶中酰胺类除草剂残留

采用磁性石墨烯纳米复合材料作为磁性固相萃取剂进行磁性固相萃取,再进行分散液液微萃取,采用气相色谱建立了高灵敏测定环境水样和绿茶中5种酰胺类除草剂残留的方法。对影响萃取效率的诸因素进行了优化。在优化条件下,5种酰胺类除草剂的富集倍数在3399～4002之间,甲草胺、乙草胺、异丙甲草胺、丁草胺和丙草胺浓度在0.1～50μg/L范围内与峰面积呈良好的线性关系,线性相关系数在0.9973～0.9993之间,检出限在0.01～0.03μg/L范围内。本方法应用于河水、自来水和绿茶样品的分析,平均加标回收率在80.2%～108.4%之间,相对标准偏差在3.8%～5.8%之间。本方法操作简单、灵敏、富集倍数高。     

悬浮固化分散液液微萃取-毛细管电泳法测定水中磺酰脲类除草剂

建立了悬浮固化分散液液微萃取-毛细管电泳法同时测定水中磺酰脲类除草剂残留的方法。以十二醇为萃取剂、甲醇为分散剂,采用悬浮固化分散液液微萃取技术对水样进行分离提取,并结合毛细管电泳法进行测定。该方法可以有效提取、分离、检测水中残留的微量苯磺隆、吡嘧磺隆、苄嘧磺隆等9种磺酰脲类除草剂,各待测物在10.0~1000 μg/L范围内线性关系良好,相关系数r≥0.992,方法检出限为2.40~7.50 μg/L,方法精密度为6.55%~13.9%。将该方法用于实际水样的测定,取得了较满意的结果,加标回收率为82.0%~104%。该方法简便快速,适合水中磺酰脲类除草剂的同时测定。     

基于分子络合的分散液液微萃取与高效液相色谱联用检测环境水样中2种苯氧羧酸类除草剂

建立了基于分子络合的分散液液微萃取（DLLME）方法,以磷酸三丁酯为萃取剂,以甲醇为分散剂,与高效液相色谱联用检测了环境水样中麦草畏和2,4-二氯苯氧乙酸（2,4-D酸）2种苯氧羧酸类除草剂,对影响前处理效果的因素（包括水样的pH值、萃取剂的种类和体积、分散剂的种类和体积、反萃液的pH值、反萃液的体积和盐浓度等）进行了详细考察,在最佳萃取条件下（水样体积10 mL,水样的pH值为0~1.0、100 μL磷酸三丁酯萃取剂、1000 μL甲醇分散剂、0.01 mol/L的氢氧化钾反萃液的体积为80 μL）,2种苯氧羧酸类除草剂在0.50~1000 μg/L范围内具有良好的线性,相关系数不小于0.9985,麦草畏和2,4-D酸的检出限分别为0.44 μg/L和0.49 μg/L,富集倍数分别为85和90,在实际样品中的加标回收率为75.7%~104.0%。该方法基于分子络合反应机理,将新型萃取剂磷酸三丁酯应用于分散液液微萃取,与HPLC联用实现了麦草畏和2,4-D酸的富集与检测,为环境水样中苯氧羧酸类除草剂的检测提供了新的前处理方法。     

螺旋霉素分子印迹磁性纳米吸附剂的合成及应用

制备了一种以螺旋霉素为模板分子的分子印迹磁性纳米吸附剂。以磁性纳米Fe₃O₄为内核,经丙烯酸表面修饰后再以螺旋霉素为模板分子、甲基丙烯酸为功能单体、乙二醇二甲基丙烯酸酯为交联剂,通过表面自由基聚合反应制备得到。该吸附剂对螺旋霉素、交沙霉素、替米考星和酒石酸泰乐菌素4种大环内酯类抗生素表现出良好的富集效果（富集倍数分别为310、118、758和72）,其选择性明显优于常规C₁₈吸附剂。该吸附剂可重复使用至少6次。结合高效液相色谱-紫外检测器建立了上述4种抗生素的分析方法。方法检出限为0.53~2.75 μg/L,定量限为1.78~9.16 μg/L;在50、100和150 μg/L低中高3个添加水平下,方法回收率在80.78%~123.02%之间,相对标准偏差<15.8%（n=5）。该方法被应用于分析蜂蜜中的上述4种抗生素。     

磁性石墨烯固相萃取/原子吸收法测定环境水样中的痕量铜

以1-(2-吡咯偶氮)-2-萘酚(PAN)为络合剂络合水样中的痕量铜,以磁性石墨烯(G)纳米材料为固相萃取吸附剂,建立了测定水样中痕量铜的磁性固相萃取/火焰原子吸收分光光度法。此方法将磁性石墨烯比表面积大、吸附性能好的优点与Fe3O4纳米粒子的磁性相结合,采用的磁性固相萃取避免了传统固相萃取中离心和过滤等繁琐的操作步骤。对影响G-Fe3O4萃取效率的实验因素进行了优化。在优化实验条件下,对铜离子的富集倍数为80.4倍,线性范围为0.5～100μg/L,相关系数(r)为0.998 1,检出限为0.067μg/L,相对标准偏差为2.1%～5.2%。此方法成功地应用于矿泉水、自来水、公园湖水中铜离子含量的测定,其加标回收率为94%～103%。结果表明,该磁性石墨烯纳米材料G-Fe3O4对水样品中铜的PAN络合物具有较高的富集能力。     

月桂酸胶束电动毛细管色谱快速分离三嗪类农药的研究

以月桂酸为表面活性剂和三羟甲基氨基甲烷(Tris)组成缓冲溶液,建立了毛细管胶束电动色谱快速测定8种三嗪类农药的方法.对电泳介质的种类及浓度、pH值、操作电压和进样时间等影响因素进行了优化,在以50 mmol/L月桂酸和100 mmol/L Tris作为缓冲溶液(pH 10.0)、体积分数为20%的丙酮作有机改性剂的条件下,可以在2.2 min内实现对嗪草酮、氰草津、西草津、莠去津、扑灭通、莠灭净、扑灭津、特丁净的分离检测.结合固相萃取(SPE)对农田水样进行测定,各农药检出限为0.5～2.5μg/L,回收率为88%～106%,相对标准偏差为3.3%～5.0%.     

Fe3O4@MOF-808磁性固相萃取结合高效液相色谱法测定大米中3种二苯醚类除草剂

利用溶剂热法构筑了Fe₃O₄@MOF-808吸附剂,将其用于大米中除草醚(NIT)、乙氧氟草醚(OXY)和甲羧除草醚(BIF)3种二苯醚类除草剂的富集,结合高效液相色谱法,建立了大米中该类除草剂的分析方法。研究通过傅里叶变换红外光谱、X射线衍射仪、扫描电子显微镜以及振动样品磁强计对构筑的磁性吸附剂的结构、表面形貌及磁强度进行表征。表征结果显示,球形的Fe₃O₄纳米颗粒与八面体形貌的MOF-808成功复合,Fe₃O₄@MOF-808饱和磁化强度可达40.35 emu/g,可以满足磁性固相萃取的需求;对吸附剂用于大米中3种二苯醚类除草剂富集的磁性固相萃取条件(吸附剂用量、吸附时间、洗脱溶剂种类以及洗脱体积)进行了优化。优化结果显示,25 mg吸附剂在6 min内即可达到对目标物的完全吸附,洗脱溶剂采用0.5 mL×2的甲醇。在最优的磁性固相萃取条件下,结合高效液相色谱-紫外检测法,建立了大米中3种二苯醚类除草剂的分析方法。方法在2~300 μg/L范围内线性关系良好(r > 0.998), NIT、OXY、BIF的检出限和定量限依次为0.6、0.6、0.4 μg/kg和2.0、2.0、1.5 μg/kg,在5、10和20 μg/kg 3个加标水平下的回收率为87.3%~96.7%,相对标准偏差不超过10.8%,且富集因子在25~29之间。将所建方法用于大米中NIT、OXY、BIF的分析,各样品均未检出这3种二苯醚类除草剂。该方法具有操作简单、快速、准确的特点,适用于大米样品中除草剂的残留分析。     

离子液体均相液液微萃取-高效液相色谱法测定婴儿奶粉中5种三嗪类除草剂

建立了婴儿配方奶粉中三嗪类除草剂的均相液液微萃取-高效液相色谱分析方法。以离子液体为液液微萃取溶剂,Eclipse XDB-C18为色谱柱,乙腈和水为流动相梯度洗脱分离。详细研究了液液微萃取条件对实验结果的影响。在最优实验条件下,三嗪类除草剂的标准曲线呈良好的线性(r≥0.9992),草净津、敌草净、特丁通、特丁津和异戊乙净的检出限分别是12.1、13.8、11.8、14.6和13.7 μg/kg;婴儿配方奶粉中的加标回收率为92.2%~103.2%,相对标准偏差低于6%。该方法灵敏度高、操作简单,适用于奶粉样品中三嗪类除草剂残留的检测。     

One‐step synthesized magnetic MIL‐101(Cr) for effective extraction of triazine herbicides from rice prior to determination by liquid chromatography‐tandem mass spectrometry

The magnetic metal‐organic framework MIL‐101(Cr) material‐based solid‐phase extraction method coupled with high‐performance liquid chromatography and tandem mass spectrometry was applied to extract seven triazine herbicides in rices. Fe₃O₄/MIL‐101(Cr) was synthesized using reduction‐precipitation method, in which steps including pre‐synthesis and modification of Fe₃O₄ nanoparticles were by‐passed. Various parameters including extraction solvent type and volume, ultrasonic extraction time, amount of Fe₃O₄/MIL‐101(Cr) microspheres, adsorption time, desorption volume and time were investigated. Under optimal conditions, the proposed method had the limit of detection (S/N = 3) and the limit of quantification (S/N = 10) of 1.08–18.10 and 3.60–60.20 pg/g, respectively. Relative standard deviations calculated for all herbicides with concentrations of 2 and 20 ng/g were in the range of 0.5 to 13% (n = 3). In addition, at the two above‐mentioned concentrations, the method achieved relative recoveries percentages of 79.3 to 116.7% when applied to determine the triazine herbicides in real samples spiked. This rapid, green, non‐polluting, pre‐concentrated extraction method was successfully developed and applied to analyze herbicides in rice samples.     

Magnetic Graphene Nanoparticles for the Preconcentration of Chloroacetanilide Herbicides from Water Samples Prior to Determination by GC-ECD

A highly sensitive method for the determination of the chloroacetanilide herbicides alachlor, acetochlor, pretilachlor, butachlor, and metolachlor in environmental water samples was developed. It is based on solid-phase extraction using magnetic graphene nanocomposite (G-Fe₃O₄) as the adsorbent, followed by gas chromatography with electron capture detection. This novel adsorbent showed a great adsorptive ability toward the analytes. The main experimental parameters such as the amount of G-Fe₃O₄, extraction time, ionic strength, the pH of the sample solution, and desorption conditions were optimized. Under the optimum conditions, the enrichment factors of the method for the analytes were in the range from 649 to 1078. A good linear response was achieved in the range of 0.2–20.0 ng mL^?1, with correlation coefficients (r) varying from 0.9964 to 0.9998. The limits of detection of the method ranged from 0.02 to 0.05 ng mL^?1 and the relative standard deviations were below 4.5%. The method was successfully applied to the determination of the herbicides in environmental water samples. Recoveries of the method for the analytes were in the range of 80.7–105.3%.     

Facile preparation of a polydopamine‐based monolith for multiple monolithic fiber solid‐phase microextraction of triazine herbicides in environmental water samples

A new multiple monolithic fiber solid‐phase microextraction using a polydopamine‐based monolith as the extraction medium is proposed. The monolith was synthesized by facile in situ copolymerization of N‐methacryldopamine and dual cross‐linkers (divinylbenzene/ethylenedimethacrylate) in the presence of N ,N‐dimethylformamide. The effect of the contents of N‐methacryldopamine and porogen in the polymerization mixture on the extraction performance was investigated thoroughly. A series of characterization studies was performed to validate the structure and properties of the monolith. The prepared multiple monolithic fibers were used for the extraction of triazine herbicides in environmental water samples. After the optimization of the extraction parameters, a convenient, sensitive, cost‐effective, and environmentally friendly method for the determination of trace triazine herbicides in water samples was developed by coupling multiple monolithic fibers solid‐phase microextraction with high‐performance liquid chromatography and diode array detection. The results indicated that the limits of detection and quantification for the target compounds were 0.031–0.14 and 0.10–0.45 μg/L, respectively. Good precision and reproducibility were obtained with the relative standard deviations below 10%. The developed method was applied to the analysis of the triazine herbicides in different water samples (lake, river, and farmland waters). The recoveries of the method were in the range between 79.6 and 117%.     

Magnetic phenolic resin core-shell structure derived carbon microspheres for ultrafast magnetic solid-phase extraction of triazine herbicides

In this study, monodisperse magnetic carbon microspheres were successfully synthesized through the carbonization of phenolic resin encapsulated Fe₃O₄ core-shell structures. The magnetic carbon microspheres showed high performance in ultrafast extraction and separation of trace triazine herbicides from environmental water samples. Under optimized conditions, both the adsorption and desorption processes could be achieved in 2 min, and the maximum adsorption capacity for simazine and prometryn were 387.6 and 448.5 μg/g. Coupled with high-performance liquid chromatography-ultraviolet detection technology, the detection limit of triazine herbicides was in the range of 0.30–0.41 ng/mL. The mean recoveries ranged from 81.44 to 91.03% with relative standard deviations lower than 7.47%. The excellent magnetic solid-phase extraction performance indicates that magnetic carbon microspheres are promising candidate adsorbents for the fast analysis of environmental contaminants.     

Glass slides functionalized by 1‐carboxyethyl‐3‐methylimidazolium chloride for the determination of triazine herbicides in rice using high‐performance liquid chromatography

A novel and simple supported ionic‐liquid‐based solid‐phase extraction method for the determination of triazine herbicides in rice was developed. Glass slides were functionalized by an ionic liquid, 1‐carboxyethyl‐3‐methylimidazolium chloride, and were used for the simultaneous extraction of seven triazine herbicides in rice samples. The effects of the type of extraction solvent, the extraction time, the type and volume of loading solvent, and the type of eluting solvent on the extraction efficiency were investigated and optimized. Under the optimum operation conditions, the limits of detection for seven triazine herbicides in rice samples obtained by high‐performance liquid chromatography were 3.16–5.42 ng/g, which were lower than the maximum residue levels established by various organizations. The linear correlation coefficients were higher than 0.9975 in the concentration range of 0.015–1.08 μg/g for the seven triazine herbicides. The recoveries of the seven triazine herbicides at the two concentration levels of 0.15 and 0.45 μg/g are between 82.47 and 104.21%, with relative standard deviations of 0.69–9.19%. The intra‐ and inter‐day (n = 5) precisions for all triazine herbicides at the spiked level of 0.30 μg/g were 1.72–11.71%.     

Determination of triazine herbicides in juice samples by microwave‐assisted ionic liquid/ionic liquid dispersive liquid–liquid microextraction coupled with high‐performance liquid chromatography

A novel microextraction method, termed microwave‐assisted ionic liquid/ionic liquid dispersive liquid–liquid microextraction, has been developed for the rapid enrichment and analysis of triazine herbicides in fruit juice samples by high‐performance liquid chromatography. Instead of using hazardous organic solvents, two kinds of ionic liquids, a hydrophobic ionic liquid (1‐hexyl‐3‐methylimidazolium hexafluorophosphate) and a hydrophilic ionic liquid (1‐butyl‐3‐methylimidazolium tetrafluoroborate), were used as the extraction solvent and dispersion agent, respectively, in this method. The extraction procedure was induced by the formation of cloudy solution, which was composed of fine drops of 1‐hexyl‐3‐methylimidazolium hexafluorophosphate dispersed entirely into sample solution with the help of 1‐butyl‐3‐methylimidazolium tetrafluoroborate. In addition, an ion‐pairing agent (NH₄PF₆) was introduced to improve recoveries of the ionic liquid phase. Several experimental parameters that might affect the extraction efficiency were investigated. Under the optimum experimental conditions, the linearity for determining the analytes was in the range of 5.00–250.00 μg/L, with the correlation coefficients of 0.9982–0.9997. The practical application of this effective and green method is demonstrated by the successful analysis of triazine herbicides in four juice samples, with satisfactory recoveries (76.7–105.7%) and relative standard deviations (lower than 6.6%). In general, this method is fast, effective, and robust to determine triazine herbicides in juice samples.     

Amino functionalized magnetic covalent organic framework for magnetic solid-phase extraction of sulfonylurea herbicides in environmental samples from tobacco land

An amino-functionalized magnetic covalent organic framework composite TpBD-(NH₂)₂@Fe₃O₄ (Tp=Tp1,3,5-triformylphloroglucinol, BD-(NH₂)₂ is 3,3',4,4'-biphenyltetramine) was prepared by post-synthesis modification. Due to its abundant benzene rings and amino groups, large specific surface area and porous structure, the prepared TpBD-(NH₂)₂@Fe₃O₄ exhibits high extraction efficiency toward sulfonylurea herbicides. Based on this, a new method of magnetic solid-phase extraction with TpBD-(NH₂)₂@Fe₃O₄ as the sorbent combined with high-performance liquid chromatography and ultraviolet detection was developed for trace analysis of sulfonylurea herbicides in environmental water, soil and tobacco leaves samples from tobacco land. Under the optimized conditions, the limits of detection within 0.05–0.14 μg/L were achieved with a high enrichment factor of 217-260-fold, and the relative standard deviations were 4.9–7.5% (n = 7, c = 0.5 μg/L). The linear range was around three orders of magnitude with the square of correlation coefficient higher than 0.9936. The method was applied to analyze five sulfonylurea herbicides in the environmental water, soil, and tobacco leave samples collected from tobacco land. No sulfonylurea herbicides were detected in these samples. The recoveries of target sulfonylurea herbicides in spiked environmental water, soil, and tobacco leaf samples were found in the range of 90.7–104, 70.7–99.0, and 59.3–97.8%, respectively. The results illustrate that the established TpBD-(NH₂)₂@Fe₃O₄-magnetic solid-phase extraction- high-performance liquid chromatography–ultraviolet detection method is efficient for the analysis of trace sulfonylurea herbicides in environmental samples.     

Vortex-assisted surfactant-enhanced-emulsification liquid-liquid microextraction for the determination of triazine herbicides in water samples by microemulsion electrokinetic chromatography

A novel method based on the combination of microemulsion electrokinetic chromatography (MEEKC) and vortex‐assisted surfactant‐enhanced‐emulsification liquid–liquid microextraction (VSLLME) was developed for the determination of five triazine herbicides (simazine, atrazine, ametryn, prometryn, and terbutryn) in water samples. The five triazine herbicides were baseline separated by using the microemulsion buffer containing a 10 mmol/L borate buffer at pH 9.5, 2.5% (w/v) SDS as surfactant, 0.8% (w/v) ethyl acetate as oil phase, and 6.0% (w/v) 1‐butanol as cosurfactant. The optimum extraction conditions of VSLLME were as follows: 100 μL chloroform was used as extraction solvent, 5.0 × 10^?5 mol/L Tween‐20 was chosen as the surfactant to enhance the emulsification, and the extraction process was carried out by vortex mixing for 3 min. Under these optimum experimental conditions, the calibration curve was linear in the range of 2.0–200.0 ng/mL, with the correlation coefficients (r²) varying from 0.9927 to 0.9958. The detection limits of the method varied from 0.41 to 0.62 ng/mL. The purposed method was applied to the determination of five triazine herbicides in real water samples, and the recoveries were between 80.6 and 107.3%.     

Simultaneous determination of simazine,cyanazine, and atrazine in honey samples by dispersive liquid–liquid microextraction combined with high‐performance liquid chromatography

A rapid and simple sample preparation method was developed for simultaneous determination of three triazine herbicides in honey samples. The selected herbicides were extracted from honey samples by ionic liquid dispersive liquid–liquid microextraction, separated on a C₁₈ column (250 mm × 4.6 mm id, 5 μm) using acetonitrile and H₂O as the mobile phase with gradient elution, and then detected by high‐performance liquid chromatography. The parameters, such as the type and volume of the extraction and disperser solvent, ion strength, pH, extraction time, and centrifuge time were optimized in order to provide the excellent extraction performance. Good linearity was showed for all the target herbicides over the tested concentration range with correlation coefficient higher than 0.994. Three spiked levels (0.005, 0.05, 0.10 mg/kg) were applied for determination of the recoveries of the targets in honey samples in the range of 80–103% with relative standard deviations not larger than 10.6%. The limits of quantification for the analytes ranged between 1.5 and 4.0 μg/kg. The developed method was applied for determination of the target compounds residues in real samples.