固相萃取-气相色谱法检测枸杞子中啶虫脒的残留量

采用固相萃取-气相色谱法检测枸杞子中啶虫脒残留量。用乙腈提取样品中的啶虫脒,活性炭和中性氧化铝串联固相萃取柱净化,用气相色谱微电子捕获检测器进行检测。在0.02~5.0mg/L的浓度范围内,啶虫脒的线性关系良好,相关系数r=0.9999,回收率在81.3%~108.8%之间,检出限为0.005mg/kg。该方法可用于枸杞子中啶虫脒残留量的测定。     

烟草中啶虫脒残留量的测定

建立了烟草中啶虫脒残留量的气相色谱检测方法.样品采用乙腈提取,经弗罗里硅土层析柱净化,用环己烷-异丙醇(体积比为9∶1)溶液淋洗,用电子捕获检测器进行测定.结果表明,该方法的回收率为82.8%～100.3%,相对标准偏差小于5%(n=5),检出限为0.18 μg/g.该法适合于烟草中啶虫脒残留量的检测.     

分子印迹膜协同银增强电化学信号高灵敏特异性检测啶虫脒

以啶虫脒为模板分子,壳聚糖为功能单体,戊二醛为交联剂,协同Ag颗粒增强导电性,在丝网印刷电极表面合成分子印迹膜,研制了测定啶虫脒的分子印迹传感器。通过循环伏安法(CV)对传感器的性能进行研究,在扫描速率100 mV/s的最优条件下,CV测试表明,啶虫脒浓度在0.01~1.0μmol/L的浓度范围内呈现良好的线性关系(线性相关系数R^2=0.9342)。分子印迹传感器具有良好的印迹效果,相较于其他农药如吡虫啉、水胺硫磷、乙草胺,对啶虫脒有较高的特异性识别能力。构建了啶虫脒分子印迹传感器的动力学吸附模型,测得传感器的印迹因子(β)为3.61,结合速率(k)为19.46 s。传感器用于水样中啶虫脒的测定,加标回收率在92.9%~100.4%。     

高效液相色谱法测定黄瓜和油菜中的啶虫脒残留量

建立了一种高效液相色谱测定黄瓜和油菜中啶虫脒农药残留的方法。以乙腈提取,弗罗里硅土净化,采用Agilent 1100高效液相色谱仪带DAD检测器对待测组份进行了分离和测定,检测波长254 nm,使用C18不锈钢反相柱（250 mm×4.6 mmi.d.,5μm）,以V（乙腈）∶V（水）=30∶70作流动相,啶虫脒在0.05-2.00mg/L范围内呈良好的线性关系（r=0.9999）,方法的添加回收率范围为73.7%-85.6%。RSD为2.2%-10.3%,能够满足啶虫脒在黄瓜和油菜中残留分析的要求。     

气相色谱法测5种农产品中啶虫脒残留量

采用V(丙酮)∶V(正已烷)=1∶2混合溶剂提取,LC-18SPE小柱净化,建立了啶虫脒在5种农产品上残留的气相色谱-ECD分析法,以保留时间和外标法定性、定量。结果表明,该方法的最低检出限为0.004 mg/kg,不同水平的加标回收率范围为73.2%~108.7%,RSD(n=6)为6.75%~12.6%。方法可用于茶叶,干香菇,木耳,萝卜,洋葱中啶虫脒残留量的测定。该方法也可为其他农产品中啶虫脒残留量的测定提供参考。     

快速溶剂萃取-高效液相色谱法测定蔬菜中啶虫脒残留量

提出了高效液相色谱法测定蔬菜中啶虫脒残留量的方法。样品以甲醇为萃取溶剂经加速溶剂萃取仪在100℃静态萃取5min,提取液浓缩后采用Dionex C18色谱柱分离,以甲醇-水(40+60)为流动相淋洗,于波长254nm处测定。啶虫脒的质量浓度在0.01～0.2g.L-1范围内与峰面积呈线性关系,方法的检出限(3S/N)为0.01mg.kg-1。以蔬菜样品为基体,在5个浓度水平进行加标回收试验,啶虫脒的回收率在99.2%～101%之间,测定值的相对标准偏差(n=5)在1.3%～3.2%之间。     

核酸适体包被胶体金检测啶虫脒残留量

采用核酸适体和胶体金技术建立了快速检测啶虫脒农药残留含量的方法。选用柠檬酸钠还原法制备胶体金,利用能够特异性识别啶虫脒的核酸适体包被于胶体金表面,通过胶体金团聚显色法,利用紫外可见分光光度计扫描核酸适体包被的胶体金检测体系,依据吸光度比值检测啶虫脒的含量。实验结果表明,核酸适体在啶虫脒的检测中具有较高的选择性;在啶虫脒含量大于50 mol/L的情况下,能够观测到明显的颜色变化,检测体系可视化程度较高。在5×10~(-3)~1.25 mmol/L范围内,啶虫脒溶液浓度与吸光度的比值A_(620nm)/A_(520nm)呈现较好的线性响应。该比色法是一种快速、灵敏、容易操作的农药残留检测方法。     

电化学方法对农药啶虫脒的间接测定

啶虫脒本身不具有电化学性质,而其在NaOH溶液中的水解产物为电活性物质。采用循环伏安法(CV)、示差脉冲伏安法(DPV)研究了啶虫脒水解产物在碳糊电极上的电化学行为,并初步探讨了其反应机理。在pH9.0的磷酸盐缓冲液(PBS)中,啶虫脒水解产物在约0.9 V(vs.SCE)产生一灵敏的氧化峰,表明电极反应是受扩散控制的不可逆氧化过程。基于啶虫脒水解产物的氧化行为,以0.9 V为工作电位,采用计时安培法进行测定,其响应电流与啶虫脒的浓度在2.0×10-7~2.8×10-5mol/L范围内呈良好的线性关系,方法的检出限为1.0×10-7mol/L。该方法成本低、操作方便、重复性好,对人体与环境无毒害,将其用于啶虫脒实际样品的测定,结果满意。     

高效液相色谱法测定啶虫脒含量的不确定度评定

按照HG 3754—2004《啶虫脒可湿性粉剂》对啶虫脒含量进行了测定,通过建立数学模型,对测量不确定度来源进行了分析、评定和量化。当啶虫脒含量为102．1g／kg时,合成不确定度为2．1g／kg,扩展不确定度为4．2g／kg（k=2）。     

韭菜中吡虫啉和啶虫脒残留的微波处理-逆固相分散法净化及液相色谱检测

建立了韭菜中两种烟碱类农药吡虫啉和啶虫脒残留的快速检测方法.韭菜样本用微波炉加热处理,使酶钝化消除含硫基质干扰,然后用乙腈提取、逆固相分散净化,用反相高效液相色谱-二极管阵列检测器检测.在0.05～2.0 mg/kg添加水平范围内,吡虫啉的平均添加回收率在95.2%～105.3%之间;相对标准偏差在0.8%～7.8%之间;啶虫脒的平均添加回收率在97.4%～108.8%之间;相对标准偏差在1.3%～8.3%之间.本方法对吡虫啉的检出限(LOD)为0.0078 mg/kg,定量检出限(LOQ)为0.026 mg/kg;对啶虫脒的检出限为0.0075 mg/kg,定量检出限为0.025 mg/kg.     

西兰花中13种有机含磷农药在不同色谱柱上的色谱保留行为

应用Agilent GC 6890气相色谱仪(附FPD检测器)对13种残留于西兰花中的有机含磷农药(OPP′s)在4种不同极性的毛细管色谱柱(即DB-1、DB-5、DB-1701及DB-35MS)上的保留行为作了研究。结果表明:采用由DB-5及DB-1701串联组成的色谱柱单元,西兰花中13种残留OPP′s可达到有效分离和测定。     

The Isolation and Determination of Sulforaphane from Broccoli Tissues by Reverse Phase‐High Performance Liquid Chromatography

Sulforaphane is a cognate isothiocyanate of glucoraphanin, released by degradation of glucosinolate through myrosinase enzyme, when Brassica tissues are crushed or chewed. C₈ analytical column and mixture of water/acetonitrile 65/35 (ν/ν) as mobile phase were used to separate sulforaphane in broccoli tissues (e.g., 7‐day‐seedling, seed, floret and leave). Confirmation of sulforaphane in crude extract of broccoli tissues was monitored using gas chromatography‐mass spectroscopy (GC‐MS). The highest amount of sulforaphane (1216 μg/g dry weight) found in 7‐day‐seedling. This method is suitable for routine screening of plant materials and proposes a low cost and robust technique for the analysis of sulforaphane.     

Determination of Fipronil in Acetamiprid Formulation by Attenuated Total Reflectance-Mid-Infrared Spectroscopy Combined with Partial Least Squares Regression

There is a high demand for rapid determination of fipronil in pesticide preparations because it has been restricted and even prohibited in many countries. An infrared-based methodology was developed for this analyte in acetamiprid formulations by attenuated total reflectance mid-infrared spectroscopy. The quantitative calibration models of fipronil were established by partial least squares regression. The determination coefficients (R²) of the model were above 0.99 while both the root mean square error of prediction and root mean square error of calibration were below 0.0011, which showed the partial least squares model accurately predicted fipronil concentrations in acetamiprid. The accuracy was further demonstrated by comparison with another two models' results of low (<1.0%, w/w) and high concentration sample sets (1.0%–4.5%, w/w). These results demonstrate the potential of infrared spectroscopy to quickly detect fipronil in acetamiprid.     

Dummy template surface molecularly imprinted polymers based on silica gel for removing imidacloprid and acetamiprid in tea polyphenols

Dummy template surface molecularly imprinted polymers based on silica gel were prepared through the surface molecular imprinting technique. Nonpoisonous nicotinamide, which is a structural analogue of imidacloprid and acetamidine, was chosen as the dummy template molecule. The obtained polymers were characterized using scanning electron microscopy, Fourier transform infrared spectroscopy, and X‐ray diffraction. The results showed that the polymers exhibited high adsorption capacity and selectivity for imidacloprid and acetamiprid. The maximum adsorption capacities of the polymers toward imidacloprid and acetamiprid were 42.05 and 22.99 mg/g, and the adsorption could reach binding equilibrium within 150 min. The polymers were successfully applied as column‐filling materials to extract imidacloprid and acetamiprid from tea polyphenols with a relatively high removal rate (92.36 and 95.20%). The polymers also showed great stability and reusability during the application. The obtained polymers possessed good application prospects for removing imidacloprid and acetamiprid in tea polyphenol production processes.     

Determination of deoxyribonucleic acids by a resonance light scattering technique and its application

For the first time, acetamiprid has been used to determine nucleic acid (DNA) using the resonance light scattering (RLS). The RLS of acetamiprid was greatly enhanced by DNA in the range of pH 1.6-1.8. A RLS peak at 313 nm was found, and the enhanced intensity of RLS at this wavelength was proportional to the concentration of DNA. The linear range of the calibration curve was 0-11.0 microg ml(-1) with the detection limit of 20 ng ml(-1). The nucleic acids in synthetic sample and in rice seedling extraction were determined satisfactorily. The interaction mechanism of acetamiprid and DNA is discussed. Mechanism studies show that the enhanced RLS is due to the aggregation of acetamiprid in the presence of DNA.     

Determination of acetamiprid by a colorimetric method based on the aggregation of gold nanoparticles

A method was developed for the detection of the insecticide acetamiprid based on the strong interaction of the cyano group of acetamiprid with gold nanoparticles (AuNPs). The interaction results in the aggregation of gold nanoparticles and is accompanied by a color change from red to purple. The concentration of acetamiprid can be determined qualitatively and quantitatively by visually monitoring the color change or by using a spectrometer. Transmittance electron microscopy and UV-vis spectroscopy have been used to characterize the process. The experimental parameters were optimized with regard to the size of the AuNPs, pH, and incubation time. Under optimal experimental conditions, linear relationships between the logarithm of the concentration of acetamiprid and the absorbance were found over the range of 0.66 to 6.6???M for AuNPs with diameters of 22.0?±?1.0?nm and of 6.6?C66???M for AuNPs with diameters of 15.0?±?1.0?nm. This method was successfully applied to detect acetamiprid in vegetables.

Development of validated LC-MS/MS method for imidacloprid and acetamiprid in parsley and rocket and evaluation of their dissipation dynamics

Fast and efficient method based on quick, easy, cheap, effective, rugged and safe followed by liquid chromatography–tandem mass spectrometry for acetamiprid and imidacloprid residues determination in parsley and rocket was developed and validated. Linearity (R²) ranged from 0.996 to 0.999. Accuracy ranged from 95.9 to 99.1%. Precision was <11%. Limit of quantification was 2.8–10.3?µg/kg. Matrix effect was evaluated. Dissipation of acetamiprid and imidacloprid in parsley and rocket was investigated under open field conditions. The dissipation behavior of both compounds followed first-order kinetics. Half-lives (t_1/2) were 2.68 and 4.24 days with dissipation rate (k) values of 0.25 and 0.165 days^?1 for acetamiprid; 0.24 (in parsley) and 0.25 (in rocket) days^?1 with k values of 0.636 (in parsley) and 0.718 (in rocket) days for imidacloprid. Preharvest interval values were 5.53 and 1.42 days for acetamiprid; 2.5 and 0.49 days for imidacloprid in parsley and rocket, respectively. Residues of both compounds were searched in real samples. None of the real samples violated maximum residues limits of the European Commission regulations.     

Highly Sensitive Silver Nanorod Arrays for Rapid Surface Enhanced Raman Scattering Detection of Acetamiprid Pesticides

The determination of pesticide residue on agricultural products is increasingly important.Exposure to pesticides can cause severe acute reactions in humans, including aplastic anemia and leukemia.In this work, we developed a rapid and sensitive method to detect acetamiprid pesticide residue based on surface-enhanced Raman scattering.Silver nanorod (AgNR) arrays were fabricated by oblique angle deposition technology and were used as SERS substrates.Prior to detection, the AgNR arrays were cleaned with nitric acid solution or a mixture of methanol and acetone.Compared to the unwashed AgNR arrays, the AgNR arrays washed with methanol and acetone shows a signal enhancement 1000 times greater than the unwashed AgNR array due to the effective removal of the impurities on its surface.The limit of detection of acetamiprid was determined to be 0.05 mg/L.In addition, the molecular structure of acetamiprid was simulated and the corresponding vibration modes of the characteristic bands of acetamiprid were calculated by density function theory.To demonstrate its practical application, the AgNRs array substrates were applied successfully to the rapid identification of acetamiprid residue on a cucumber's surface.These results confirmed possibility of utilizing the AgNRs SERS substrates as a new method for highly sensitive pesticide residue detection.