基于非对称流场流分离技术的纳米银分离监测方法

Separating and monitoring of Ag nanoparticles via the asymmetrical flow field-flow fractionation

以纳米银（AgNPs）作为典型的纳米颗粒物,利用非对称流场流分离技术构建纳米颗粒物的分离监测方法。制备了柠檬酸盐稳定的AgNPs分散液,采用透射电镜、紫外可见分光光度计、Zeta电位分析仪对AgNPs分散液进行了表征。结果表明,AgNPs半径多数小于10 nm,最大吸收波长为400 nm,Zeta电位为-42.56 m V。采用非对称流场流分离仪对AgNPs进行粒径分离,得到UV-Vis信号谱图,并收集得到半径小于10 nm、10~30 nm、30~50 nm、50~70 nm、70~100nm范围的AgNPs颗粒,结合电感耦合等离子体质谱仪测定每个粒径范围内AgNPs的质量浓度。结果表明,该方法重现性良好,AgNPs在半径小于10 nm的范围内达到了UV-Vis吸收峰值,响应信号最高为0.022 5~0.027 5 V,表明半径小于10 nm的AgNPs浓度较高。半径小于10 nm、10~30 nm、30~50 nm、50~70 nm、70~100 nm范围内AgNPs的质量浓度分别为（1 021.86±61.74）μg/L、（323.23±45.83）μg/L、（72.90±32.14）μg/L、（44.64±9.28）μg/L、（39.12±5.04）μg/L,回收率为43.96%±0.84%。

This paper is aimed to introduce a method for nanoparticles separation and monitoring by using the asymmetrical flow field-flow fractionation（ AF4）. In the paper,we have used of Ag nanoparticles（ AgNPs） as a typical kind of nanoparticles. We have synthesized citrate stabilized AgNPs,which would then be characterized by such means as the transmission electron microscope（ TEM） and UV-Vis spectrophotometer as well as the Zeta potential analyzer. The results of our analysis show that the diameter of the aforementioned AgNPs has now no longer been than 10 nm at most. The maximum absorption wavelength of the AgNPs can be as long as 400 nm. The Zeta potential of the AgNPs suspension is-42. 56 m V,suggesting that the AgNPs synthesized enjoy nice stability for dispersion. What is more,the asymmetrical flow field-flow fractionation（ AF4） has been used to classify the newly made AgNPs into different diameter ranges. In addition,we have been successful in gaining the UV-Vis absorption spectrum by using the online UV-Vis spectrophotometer coupled with AF4. Besides,we have also collected AgNPs in the five diameter ranges by using the online fraction collector,that is,below 10 nm,10-30 nm,30-50 nm,50-70 nm and 70-100 nm.The concentration of AgNPs for the different diameter ranges can be identified by using an inductively coupled plasma mass spectrometer（ ICP-MS）. Hence,the results of our study show that the method we have developed is endowed with the perfect reproducibility. Furthermore,the AgNPs we have synthesized proves to have the highest UV-Vis response below the diameter of 10 nm,which tends to reveal that the concentration of AgNPs within this diameter range turns to be higher than AgNPs in all the other diameter ranges. The highest detector voltage of UV-Vis spectrophotometer is 0. 022 5-0. 027 5 V. To be exact,the concentrations of 10-30 nm,30-50 nm,50-70 nm and 70-100 nm,can be（ 1 021. 86 ± 61. 74） μg/L,（ 323. 23 ± 45. 83） μg/L,（ 72. 90± 32. 14） μg / L,（ 44. 64 ± 9. 28） μg / L and（ 39. 12 ± 5. 04）μg /L,respectively,which is consistent with the TEM image and online UV-Vis signals. The recovery rate can be 43. 96% ±0. 84%. The chief reason for the sample loss comes due to the sample adsorption on AF4 injector,which can be reduced by rectifying the injection volume. Thus,the method we have developed in this paper can be adopted for separating and monitoring of AgNPs.