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New chromium(III) ion-imprinted polymers (IIPs) intended for selective removal of Cr(III) ions from aqueous media were prepared using Cr(III)-1,10-phenanthroline complex as a template by bulk polymerization. The properties of IIPs synthesized using different functional monomers, including acidic (methacrylic acid) and neutral (styrene) agents, polar protic and aprotic porogens (ethanol, acetonitrile) and initiators (2,2′-azobisisobutyronitrile, lauroyl peroxide), were studied in terms of their morphology, sorption properties towards Cr(III) ions, selectivity and reusability. The polymer's particles were characterized using FT-IR, nitrogen adsorption/desorption analysis and scanning electron microscopy. The analytes, Cr(III) ions, were quantitatively retained on the IIPs at pH 4.5 and eluted with 0.1 mol L − 1 EDTA solution. Our studies showed that the neutral functional monomer, aprotic solvent and azo initiator provided the best selectivity and sorption properties of IIP. Under optimal conditions, Cr(III)-IIP prepared using ST and AIBN showed good selectivity, reusability and stability. The selectivity coefficient was 16.7, 9.6 and 4.4 for Cr(III)/Cu(II), Cr(III)/Fe(III) and Cr(III)/Mn(II), respectively. Good reproducibility of the results, obtained even after a hundred cycles, testifies to the long-term stability of the sorbents. IIP(4)ST-AIBN can successfully be used as a sorbent in solid phase extraction to selective chromium separation from the water solution.

A multi-commutation flow analysis system using on-line solid phase extraction and flame atomic absorption spectrometric detection (MCFA-FAAS) was developed for the study of chromium speciation in sewage samples. A new chromium imprinted polymer was prepared and applied as a selective sorbent for the separation and preconcentration of Cr(III) ions. The polymer was prepared using a Cr(III)-8-hydroxyquinoline complex as a template, styrene as a functional monomer, and divinylbenzene as a crosslinking monomer using 2,2′- azobisisobutyronitrile as an radical initiator for bulk polymerization. The chromium imprinted polymer exhibits good chemical and mechanical stability, sorption capacity and selectivity towards Cr(III) ions. The analyte, Cr(III) ions, was quantitatively retained on the sorbent at pH 9, eluted with 0.3 mL of 0.1 mol L−1 nitric acid and determined by FAAS with a detection limit of 2.1 ng mL−1 and a 33-fold preconcentration factor obtained with a 10 min loading time. The MCFA-FAAS system is fully automated and enables analysis of 1 mL of sample in 4.5 min, which gives a throughput of 12 samples per hour. The accuracy of the proposed method was proved by analysis of a reference material of wastewater RES 10.2 (ielab). The method was successfully applied to the determination of trace amounts of Cr(III) in municipal sewage samples.

The biological activity of Cr(III) and Cr(VI) species, their chemical behavior, and toxic effects are dissimilar. The speciation analysis of Cr(III) and Cr(VI) in environmental matrices is then of great importance and much research has been devoted to this area. This review presents recent developments in on-line speciation analysis of chromium in such samples. Flow systems have proved to be excellent tools for automation of sample pretreatment, separation/preconcentration of chromium species, and their detection by various instrumental techniques. Analytical strategies used in chromium speciation analysis discussed in this review are divided into categories based on selective extraction/separation of chromium species on solid sorbents and liquid-liquid extraction of chromium species. The most popular strategy is that based on solid-phase extraction. Therefore, this review shows the potential of novel materials designed and used for selective binding of chromium species. The progress in miniaturization of measurement systems is also presented.