Gurnani Vibha, Singh Ajai K, Venkataramani B
Department of Chemistry, Indian Institute of Technology, Hauz Khas, New Delhi 110016, India.
Talanta. 2003 Dec 23;61(6):889-903. doi: 10.1016/S0039-9140(03)00373-4.
Pyrocatechol is immobilized on cellulose via NHCH(2)CH(2)NHSO(2)C(6)H(4)NN linker and the resulting macromolecular chelator characterized by IR, TGA, CPMAS (13)C NMR and elemental analyses. It has been used for enrichment of Cu(II), Zn(II), Fe(III), Ni(II), Co(II), Cd(II) and Pb(II) prior to their determination by flame atomic absorption spectrometry (FAAS). The pH ranges for quantitative sorption (98.0-99.4%) are 4.0-7.0, 5.0-6.0, 3.0-4.0, 5.0-7.0, 5.0-8.0, 7.0-8.0 and 4.0-5.0, respectively. The desorption was found quantitative with 0.5 mol dm(-3) HCl/HNO(3) (for Pb). The sorption capacity of the matrix for the seven metal ions has been found in the range 85.3-186.2 mumol g(-1). The optimum flow rate of metal ion solution for quantitative sorption of metal onto pyrocatechol functionalized cellulose as determined by column method, is 2-6 cm(3) min(-1), whereas for desorption it is 2-4 cm(3) min(-1). The tolerance limits for NaCl, NaBr, NaI, NaNO(3), Na(2)SO(4), Na(3)PO(4,) humic acid, EDTA, ascorbic acid, citric acid, sodium tartrate, Ca(II) and Mg(II) in the sorption of all the seven metal ions are reported. Ascorbic acid is tolerable up to 0.8 mmol dm(-3) with Cu and Pb where as sodium tartrate does not interfere up to 0.6 mmol dm(-3) with Pb. There is no interference of NaBr, NaCl and NaNO(3) up to a concentration of 0.5 mol dm(-3), in the sorption of Cu(II), Cd(II) and Fe(III) on to the chelating cellulose matrix The preconcentration factors are between 75 and 300 and t(1/2) values </=5 min for all the metal ions. Simultaneous sorption of Cu, Zn, Ni and Co is possible at pH 5.0 if their total concentration does not exceed lowest sorption capacity. The present matrix coupled with FAAS has been used to enrich and determine the seven metal ions in river and tap water samples (relative standard deviation (R.S.D.) 1.05-7.20%) and synthetic certified water sample SLRS-4 (NRC, Canada) with R.S.D. approximately 2.03%. The cobalt present in pharmaceutical vitamin tablets was also preconcentrated on the modified cellulose and determined by FAAS (R.S.D. approximately 1.87%).
邻苯二酚通过NHCH(2)CH(2)NHSO(2)C(6)H(4)NN连接体固定在纤维素上，所得大分子螯合剂通过红外光谱、热重分析、交叉极化/魔角旋转(13)C核磁共振和元素分析进行表征。它已用于在通过火焰原子吸收光谱法(FAAS)测定之前富集Cu(II)、Zn(II)、Fe(III)、Ni(II)、Co(II)、Cd(II)和Pb(II)。定量吸附(98.0 - 99.4%)的pH范围分别为4.0 - 7.0、5.0 - 6.0、3.0 - 4.0、5.0 - 7.0、5.0 - 8.0、7.0 - 8.0和4.0 - 5.0。发现用0.5 mol dm(-3) HCl/HNO(3)(用于Pb)解吸是定量的。已发现该基质对七种金属离子的吸附容量在85.3 - 186.2 μmol g(-1)范围内。通过柱法测定，金属离子溶液在邻苯二酚功能化纤维素上定量吸附金属的最佳流速为2 - 6 cm(3) min(-1)，而解吸时为2 - 4 cm(3) min(-1)。报告了在所有七种金属离子吸附过程中NaCl、NaBr、NaI、NaNO(3)、Na(2)SO(4)、Na(3)PO(4)、腐殖酸、EDTA、抗坏血酸、柠檬酸、酒石酸钠、Ca(II)和Mg(II)的耐受限度。Cu和Pb存在时，抗坏血酸在浓度高达0.8 mmol dm(-3)时可耐受，而酒石酸钠在浓度高达0.6 mmol dm(-3)时对Pb不产生干扰。在Cu(II)、Cd(II)和Fe(III)吸附到螯合纤维素基质上的过程中，浓度高达0.5 mol dm(-3)时，NaBr、NaCl和NaNO(3)不产生干扰。所有金属离子的预富集因子在75至300之间，t(1/2)值≤5分钟。如果Cu、Zn、Ni和Co的总浓度不超过最低吸附容量，则在pH 5.0时可以同时吸附。目前的基质与FAAS联用已用于富集和测定河水和自来水样品中的七种金属离子(相对标准偏差(R.S.D.)为1.05 - 7.20%)以及合成标准水样SLRS - 4(加拿大国家研究委员会)，R.S.D.约为2.03%。药物维生素片中存在的钴也在改性纤维素上进行了预富集，并通过FAAS测定(R.S.D.约为1.87%)。
