Pacheco Pablo H, Smichowski Patricia, Polla Griselda, Martinez Luis D
Instituto de Química de San Luis (INQUISAL-CONICET), Chacabuco y Pedernera, CP 5700, San Luis, Argentina.
Talanta. 2009 Jul 15;79(2):249-53. doi: 10.1016/j.talanta.2009.03.050. Epub 2009 Apr 1.
A study was performed to assess the performance of aminoacids immobilized on carbon nanotubes (CNTs) for their employment as a sorbent for solid phase extraction systems. An immobilization method is introduced and the aminoacid L-tyrosine was chosen as a case study. A spectrophotometric study revealed the amount of aminoacid immobilizated on CNTs surface, and it turned to be of 3174 micromol of L-tyrg(-1). The material was tested for Co retention using a minicolumn inserted in a flow system. At pH 7.0, the amount of Co retained by the column was of 37.58+/-3.06 micromol Co g(-1) of CNTs. A 10% (v/v) HNO(3) solution was chosen as eluent. The pH study revealed that Co binding increased at elevated pH values. The calculation of the mol ratio (moles of Co bound at pH 9 to moles of l-tyr) turned to be 3:1. The retention capacity was compared to other bivalent cations and showed the following tendency: Cu(2+)>Ni(2+)>Zn(2+)>>Co(2+). The analytical performance was evaluated and an enrichment factor of 180 was obtained when 10 mL of 11.37 microg L(-1)Co solution was loaded onto the column at pH 9.0; reaching a limit of detection (LoD) of 50 ng L(-1). The proposed system was successfully applied to Co determination in QC-LL2 standard reference material (metals in natural water).
进行了一项研究，以评估固定在碳纳米管（CNT）上的氨基酸作为固相萃取系统吸附剂的性能。介绍了一种固定方法，并选择氨基酸L-酪氨酸作为案例研究。分光光度研究揭示了固定在CNT表面的氨基酸量，结果为3174微摩尔L-酪氨酸（-1）。使用插入流动系统的微型柱测试了该材料对钴的保留能力。在pH 7.0时，柱保留的钴量为37.58±3.06微摩尔钴每克（-1）CNT。选择10%（v/v）硝酸溶液作为洗脱剂。pH研究表明，在较高pH值下钴的结合增加。计算摩尔比（pH 9时结合的钴摩尔数与L-酪氨酸摩尔数之比）结果为3:1。将保留容量与其他二价阳离子进行比较，显示出以下趋势：Cu(2+)>Ni(2+)>Zn(2+)>>Co(2+)。评估了分析性能，当在pH 9.0下将10 mL 11.37微克/升的钴溶液加载到柱上时，获得了180的富集因子；检测限（LoD）达到50纳克/升。所提出的系统成功应用于QC-LL2标准参考物质（天然水中的金属）中钴的测定。
