介孔SiO_2分离富集-火焰原子吸收法测定果汁中痕量铅

研究了介孔SiO_2分离富集-火焰原子吸收法测定果汁中痕量铅的新方法。探讨了溶液pH值、吸附温度、吸附时间、洗脱条件及共存离子对铅分离富集的影响。结果表明:在pH值为7.0、25℃吸附15 min条件下,Pb~(2+)可被介孔定量吸附,其静态饱和吸附容量为9.95 mg/g。吸附在介孔SiO_2上的可用0.05 mol/L EDTA完全洗脱。该方法线性范围0.2~10.0μg/m L,检出限为2.04 ng/m L,相对标准偏差(RSD)为3.4%(n=11,ρ=2.0μg/m L)。加标回收率为95.0%~97.5%。该方法可用于食品果汁样品中痕量铅的测定。

Determination of Lead in Fruit Juice by Flame Atomic Absorption Spectrometry after Separation/Preconcentration with Mesoporous SiO2

A new method for the determination of trace lead based on mesoporous separation/preconcentration by flame atomic adsorption spectrmetry (FAAS) was studied.In this process,the effects of pH of solution,temperature,time,elution conditions and co-existing ion on preconcentration of trace lead were investigated.It was found that the mesoporous SiO2 show quantitative adsorption toward Pb2+ with relatively high selectivity from a solution buffered at 7.0,at the temperature of 25 and adsorption time of 15 min.The value of static saturated adsorption capacity was 9.95 mg/g,the pb2+ adsorbed on mesoporous SiO2 was eluted with 0.05 mol/L EDTA.The linear range of determination was 0.2～10.0 μg/mL.The detection limit of this method for pb2+ was 2.04 ng/mL,and the relative standard deviation (RSD) was 3.4％ (n=11,ρ=2.0 μg/mL).The recoveries of pb2+ ranged from 95.0 ％ to 97.5 ％.The proposed method has been applied to determination of lead in fruit juices samples with satisfactory results.