ИСТИНА

The preconcentration of trace metals retains a strong interest in analysis of complex samples. A numerous types of various chelating resins with functional groups designed for group and individual metal selectivity have been developed. Usually the chelating resins are prepared by covalent bonding of specific organic reagents such iminodiacetic acid, 8-hydroquinoline, amidoxime and others onto the surface of suitable matrix [1]. The preparation of chelating resins is not trivial task and the properties of covalently bound reagents could be different from those observed for free form of these reagents. Also, a highly selective preconcentration of certain metal or few metals can be achieved only with application of specific resin, so normally a set of expensive chelating resins with various is required for different type of analysis. The application of universal analytical platform for immobilisation of various organic reagents under mild conditions could be solution of above mentioned problem. Recently, a new platform PHMG@SiO2 comprising porous silica matrix coated with a layer of physically adsorbed cationic polymer (polyhexamethyleneguanidine or PHMG) was designed for this purpose [2]. This simply prepared stable anion-exchange material can easily coated with a third layer of specific to certain metals sulphonated organic reagents including Arsenazo I, Tiron, Alizarine S, Nitroso-R-Salt and others [2,3]. In total, the adsorption of more than 150 organic various reagents have been investigated for the preparation of new selective adsorbents. The strong retention of organic reagents at the of PHMG@SiO2 is due to electrostatic interactions between protonated primary and secondary amino-groups at the surface of PHMG@SiO2 and dissociated sulpho-, carboxy- and arsenic acid groups in the molecules. Hydrogen bonding of amino- groups with phenolic and carboxylic groups can also impact in retention of organic reagents. The regularities of adsorption of transition, heavy and rare-earth metals were studied for the prepared chelating adsorbents. The most selective adsorbents were selected and used for solid phase extraction of metals from complex matrices prior ICP-MS, ICP-OES and spectrophotometric detection. The capability of immobilised photometric organic reagents to form intensively coloured surface complexes with adsorbed metals has been used for determination of metals in the phase of the adsorbent by using diffusive reflectance spectrophotometry, luminescence and visual test-methods.