8-羟基喹啉功能化磁性粒子的制备及其应用于伏安法测定水样中痕量铅

Preparation of Oxine Modified Functional Magnetic Particles and Its Application to Voltammetry Determination of Trace Amount of Lead in Water Sample

将所制备的磁性Fe3O4颗粒先后分别在乙醇和水介质中与3-氨基丙基三乙氧基硅烷(APS)和10%(体积分数)戊二醛溶液反应使Fe3O4颗粒的表面形成醛基功能化,最后在pH 6.8的磷酸盐缓冲溶液中与8-羟基喹啉(Ox)反应,生成了8-羟基喹啉功能化的磁性Fe3O4颗粒。试验表明经Ox修饰的Fe3O4颗粒对Pb2+有很强的络合作用,据此将其作为痕量铅的富集试剂应用于阳极溶出伏安法测定水样中铅含量。取水样50.0mL,加入Fe3O4/Ox颗粒在pH 6.8磷酸盐缓冲溶液中的悬浮液1.5mL,充分搅拌20min后,用磁铁在反应烧杯底部吸着磁性颗粒使与水溶液分离。于磁性颗粒中加入1mol·L^-1盐酸溶液1mL,将其表面吸着的Pb^2+溶解,用水将溶液稀释至5.0mL。以玻碳电极为工作电极,Ag/AgCl为参比电极,铂电极为对电极进行阴极电沉积50s,然后进行阳极溶出伏安测定。用铅标准溶液绘制标准曲线,Pb^2+的质量浓度在0.50 mg·L^-1以内与所测得的对应氧化电流导数值之间呈线性关系,检出限(3S/N)为0.7μg·L^-1。应用此方法分析了6个环境水样,测定值与已知值相符,测定值的相对标准偏差(n=5)为0.48%~3.5%。按标准加入法进行回收试验,测得回收率为91.0%~138%。

Magnetic Fe3O4 particles were prepared and modified by its reaction with 3-aminopropyltriethoxysilane(APS)in ethanol medium and with 10%(volume fraction)of glutarldehyde solution in aqueous medium in succession to form aldehyde groups on the surface of Fe3O4 particles.And in its further reaction with 8-hydroxyquinoline(Ox)in phosphate buffer medium of pH 6.8,thus the Ox modified functional magnetic particles of Fe3O4(abbrev as Fe3O4/Ox)was obtained.It was shown that Fe3O4/Ox particles have strong complexing action towards Pb^2+ ion.On this basis,magnetic Fe3O4/Ox particles were applied to the preconcentration and separation of trace amounts of Pb2+ from water sample for the anodic stripping voltammetric determination.In the analysis,50.0 mL of water sample were transferred to a small beaker and 1.5 mL of suspension of Fe3O4/Ox particles in pH6.8 phosphate buffer solution were added and stirred for 20 min.The magnetic particles were settled at the bottom of the beaker by the action of a magnet at outside of the beaker,and the supernatant was separated and discarded.1 mL of 1 mol·L^-1 HCl solution was added to the magnetic particles to dissolve Pb2+ from its oxine-complex adsorbed on the surface of the particles.The solution was diluted to 5.0 mL with water and analyzed by voltammetry.GCE was used as working electrode,Ag/AgCl was used as reference electrode and Pt-electrode as counter electrode.Pb^2+ ion the solution was first electrodeposited at the cathode for 50 s,and then defermined by anodic stripping voltammetry.Stardard curve was prepared with standard lead solution.Linear relationship between values of derivate of oxidation current found and the respective mass concentrations of lead was obtained within 0.50 mg·L^-1.Value of detection limit(3 S/N)found was 0.7μg·L^-1.Six samples of enviromental water were analyzed by this method,giving results in consistency with the known values.RSDs(n=5)found were in the range of 0.48%-3.5%.Recovery was tested by the standard addition method,giving values of recovery ranged from 91.0%-138%.