Magnetic nanocellulose hybrid nanoparticles and ionic liquid for extraction of neonicotinoid insecticides from milk samples prior to determination by liquid chromatography-mass spectrometry

A simple and rapid microextraction procedure is reported on the use of ionic liquid in combination with magnetic nanocellulose hybrid nanoparticles. The procedure is ultrasound-assisted and applicable to selective preconcentration of neonicotinoid insecticides from milk samples, prior to being analysed by liquid chromatography-mass spectrometry. The extraction procedure uses small volume of organic solvents (<1 mL), and there is no need for centrifugation. In the experimental approach the ionic liquid was quickly disrupted by an ultrasonic probe and dispersed in milk samples in a cloudy form. At this stage, neonicotinoid insecticides were extracted into the fine droplets of ionic liquid. Then small amounts of magnetic nanocellulose hybrid nanoparticles were dispersed into the sample solutions to adsorb the ionic liquid containing the analytes and phase separation was completed. The ionic liquid allowed the microextraction of the analytes and a small volume of acetonitrile was used for elution. Magnetic nanocellulose favoured the adsorption of the ionic liquid with the analytes and improved the final recovery with respect to the use of simple magnetic nanoparticles as a sorbent material. Under the optimum conditions, decision capabilities were achieved in the 0.02–0.06 mg kg^?1 range, with recoveries between 91.0% and 109.5%.     

电感耦合等离子体质谱法测定食品中硒元素的条件优化

目的 优化电感耦合等离子体质谱法(inductively coupled plasma mass spectrometer,ICP-MS)测定食品中硒元素含量的条件,并对河北省食品中硒元素含量情况进行调查分析.方法 选取8种不同基质的国家标准物质作为检测样品对实验条件进行优化,同时选择80Se作为检测目标,采用碰撞模式...     

Hydrogen sorption studies of palladium decorated graphene nanoplatelets and carbon samples

With the increasing population of the world, the need for energy resources is increasing rapidly due to the development of the industry. 88% of the world's energy needs are met from fossil fuels. Since there is a decrease in fossil fuel reserves and the fact that these fuels cause environmental pollution, there is an increase in the number of studies aimed to develop alternative energy sources nowadays. Hydrogen is considered to be a very important alternative energy source due to its some specific properties such as being abundant in nature, high calorific value and producing only water as waste when burned. An important problem with the use of hydrogen as an energy source is its safe storage. Therefore, method development is extremely important for efficient and safe storage of hydrogen. Surface area, surface characteristics and pore size distribution are important parameters in determining the adsorption capacity, and it is needed to develop new adsorbents with optimum parameters providing high hydrogen adsorption capacity. Until recently, several porous adsorbents have been investigated extensively for hydrogen storage. In this study, it was aimed to develop and compare novel Pd/carbon, Pd/multiwalled carbon nanotube, and Pd/graphene composites for hydrogen sorption. All the palladium/carbon composites were characterized by t-plot, BJH desorption pore size distributions, N₂ adsorption/desorption isotherms, and SEM techniques. The maximum hydrogen storage of 2.25 wt.% at −196 °C was achieved for Pd/KAC composite sample. It has been observed that the spillover effect of palladium increases the hydrogen sorption capacity.     

东方Cheese发酵过程中异黄酮、苷元及组分的研究

东方Cheese经毛霉发酵能去除某些过敏源,这种无盐制品深受日本民众欢迎。文中通过正交试验优化了东方Cheese中异黄酮的提取条件。采用了三波长二标样法和HPLC测定异黄酮含量和组成。检测了东方Cheese发酵过程中异黄酮含量及组成的变化:异黄酮的总量降低了37.90%;其中糖苷由34.02μg/mL降至3.11μg/mL(即已有90.86%糖苷转化为苷元),苷元含量则相应的由0.97μg/mL升至18.62μg/mL。认为异黄酮总量降低以及组成变化的主要因素是糖苷到苷元分子质量的降低和样品含水量提高;发酵后期限制组成变化的主要因素是底物浓度的降低。     

氨基甲酸酯类农药残留质控样品的制备与评价-以灭多威为例

目的 建立一种蔬菜冻干粉中氨基甲酸酯类农药残留质控样品的制备方法并对制备技术进行评价。方法 以圆白菜为基质, 灭多威为目标物, 采用真空冷冻干燥, 基质添加的方式制备质控样品。采用液相色谱-串联质谱法对质控样品中目标物含量进行测定。通过随机抽样测定以评估样品的均匀性, 通过观察样品12个月内目标物检测结果变化以评估样品的稳定性。结果 本方法制备的灭多威质控样品均匀性和稳定性良好。蔬菜冻干粉质控样品便于贮藏、运输且在常温下能够长期稳定保存。样品中灭多威的制备值与测得值较好吻合。结论 本研究确立了蔬菜冻干粉中灭多威质控样品的制备方法, 所建立的制备技术可以确保质控样品定值结果的准确性, 为氨基甲酸酯类农药残留质控样品制备方法的开发提供技术支持。     

菌落总数质控样的制备及其在能力验证中的应用

目的制备均匀性和稳定性符合能力验证要求的质控样品,并将质控样品用于菌落总数的能力验证。方法本次考核样品由高浓度(3×10~4 CFU)、低浓度(1×10~4 CFU)2个样品组成,随机抽取质控样品进行稳定性及均匀性的检验,对其进行评价。本设计通过对实验室进行随机分组来发放样品,防止能力验证活动中各实验室进行串通。结果 65家实验室参加本次考核活动,整体满意率为80%,本次能力验证可以真实地反映参试单位的检测水平。结论本次菌落总数能力验证样品可用于质控样品使用。     

食品微生物学样品采集操作规程的探讨

鉴于微生物学样品采集在食品检验过程中的重要性,探讨微生物样品的无菌采集操作标准化规程,规范操作,确保检测结果的准确性。本文综合多种情况多种参考方法进行归纳总结,方便实验人员了解食品微生物学样品的采集和抽样,使样品的采集更规范更严谨,确保检测质量。     

同位素稀释凝胶渗透色谱-气相色谱-质谱法测定膳食样品中16种邻苯二甲酯类物质

建立膳食样品中16种邻苯二甲酸酯的同位素稀释凝胶渗透色谱净化(GPC)-气相色谱(GC)-串联质谱(MS)检测方法。方法 加入同位素内标的膳食样品用正己烷饱和过的乙腈超声提取,GPC净化,DB-5ms 毛细管色谱柱分离(30m×0.25mm,0.25μm),GC-MS选择离子监测模式(SIM)测定,内标法定量。结果 16种邻苯二甲酸酯在8类膳食样品中的平均添加回收率为52.3%～124.7%;RSD为1.6%～16.2%;检出限为0.03～0.06mg/kg。结论 该方法简便、灵敏、准确,适用于膳食样品中邻苯二甲酸酯的检测。     

金属-有机骨架材料作为分离介质在食品生物分析中的应用

金属-有机骨架材料(metal-organic frameworks,MOFs)具有比表面积大、热稳定性好、孔径尺寸可调控、孔大小分布均匀、表面修饰可调控等特性。简述了MOFs的研究概况,论述了其作为分离介质的优点,综述了近几年其在磷酸肽、抗生素、食品添加剂、食品农药残留、有机污染物等的分析和在气体吸附、传感器中的应用。在未来,利用MOFs得到的氧化物可作为色谱固定相,应用在色谱仪器中分析生物大分子,也可以制备具有磁性的MOFs,用于蛋白质的分离提取等,这表明MOFs在食品生物分析领域具有良好的应用前景。