基于壳聚糖改性的磁性氧化石墨烯的半自动化管尖固相微萃取技术在环境水中痕量铅快速测定中的应用

Application of Semi Automated Pipette-Tip Solid-Phase Microextraction Technology Based on Chitosan Modified Magnetic Graphene Oxide in Rapid Determination of Trace Lead in Environmental Water

以戊二醛为交联剂,采用壳聚糖(CS)和四氧化三铁(Fe_(3)O_(4))修饰氧化石墨烯(GO),制备了Fe_(3)O_(4)-GO/CS复合物(吸附剂)。将20 mg Fe_(3)O_(4)-GO/CS填装于200μL微型枪头中,两端填上少量玻璃棉,枪头旁边放置磁铁。将12 mL塑料注射器和枪头连接,用塑料注射器吸取1 mL水冲洗Fe_(3)O_(4)-GO/CS表面可能吸附的杂质。环境水样经0.22μm滤膜过滤后,将滤液酸度调至pH6.0,用塑料注射器吸取10 mL,固定在注射泵上,将水样以0.8 mL·min^(-1)流量通过枪头;再吸取1 mL 0.010 mol·L^(-1)盐酸溶液(洗脱剂),以0.5 mL·min^(-1)流量洗脱吸附在Fe_(3)O_(4)-GO/CS上的铅。收集洗脱液,用电感耦合等离子体质谱法测定。结果显示:Fe_(3)O_(4)-GO/CS对铅的平衡吸附容量为126 mg·g^(-1),可重复使用50次,吸附过程符合朗缪尔(Langmuir)等温吸附模型;铅的质量浓度在0.01~10.00μg·L^(-1)内和响应值呈线性关系,检出限为0.005μg·L^(-1)。对实际水样进行3个浓度水平的加标回收试验,回收率为84.7%~105%,测定值的相对标准偏差(n=5)为0.90%~3.9%。

By modifying graphene oxide(GO)with chitosan(CS)and Fe_(3)O_(4)using glutaraldehyde as the crosslinking agent,the composite of Fe_(3)O_(4)-GO/CS(adsorbent)was prepared.The 20 mg of Fe_(3)O_(4)-GO/CS was filled into a 200μL-micro gun head,and a small amount of glass wool was filled into both ends,with a magnet around the gun head.Then the gun head was connected with a 12 mL-plastic syringe,and 1 mL of water was taken by the plastic syringe to rinse impurities that might be adsorbed on the surface of Fe_(3)O_(4)-GO/CS.Environmental water samples were passed through a 0.22μm filter membrane,and the acidity of the filtrate was adjusted to pH 6.0.Then 10 mL of water sample was taken by the plastic syringe,which was fixed on the infusion pump.The water sample was passed through the gun head at flow rate of 0.8 mL·min^(−1).Then 1 mL of 0.010 mol·L^(−1)hydrochloric acid solution(eluent)was taken for elution of lead adsorbed on Fe_(3)O_(4)-GO/CS at flow rate of 0.5 mL·min^(−1).The eluate was collected and determined by inductively coupled plasma mass spectrometry.It was shown that the equilibrium adsorption capacity of Fe_(3)O_(4)-GO/CS(which could be reused 50 times)to lead was 126 mg·g^(−1),and the adsorption process followed the Langmuir isotherm model.Linear relationship between values of the mass concentration and response value of lead was kept in the range of 0.01-10.00μg·L^(−1),with detection limit of 0.005μg·L^(−1).Test for the spiked recovery at 3 concentration levels was conducted on actual water samples,giving recoveries in the range of 84.7%-105%,and RSDs(n=5)of the determined values ranged from 0.90%to 3.9%.