Application of MnO2Resin and Dowex 1X8 manganese dioxide impregnated resin for the separation of chromium from biological samples
MnO2Resin and Dowex 1X8 manganese dioxide impregnated resin was used for chromium separation from biological samples. We examined sorption of chromium from acid solutions: hydrochloric, nitric and sulphuric in concentration range from 0.01 to 2 mol/dm3. The sorption process was evaluated by batch and column experiments. We also examined sorption of other elements in the developed systems, to check the selectivity of the process. Determination of chromium by radiochemical neutron activation analysis after separation with MnO2Resin was described.
KeywordsMnO2Resin Dowex 1X8 manganese dioxide impregnated resin Chromium sorption Radiochemical neutron activation analysis Chromium determination
Chromium is one of the elements widely distributed in the environment . The large amounts of this metal come from industrial activities like electroplating, pigment production, leather tanning, and wood processing [2, 3]. The properties of chromium depend upon oxidation states and are very different. Chromium(III) is an important microelement, which is necessary to glucose, lipid and protein metabolism. Chromium(VI) has strong oxidizing potential and can easily penetrate biological membranes. The consequences of excessive exposure to this form may be skin damage, respiratory problems or in the same case cancer of kidneys, lungs or liver [4, 5, 6, 7]. For these reasons amounts of this metal in biological and geological samples should be constantly monitored. Institutions like EPA, FAO/WHO and EU recommend the permissible content of chromium in water, food and soil [8, 9, 10, 11, 12].
Determination of chromium is often realized after separation process with the use of exchange resin. Ion exchange method gives the possibility to recover and concentrate elements of interest from samples with different matrices. This method has many advantages such as: easy recovery of the element, low operation cost, selectivity, concentration of the element of interest, removal of interfering ions and possible regeneration of the resin after processing [13, 14]. Many adsorbents are used for chromium preconcentration, e.g. Amberlite IRA-910 , Dowex 1X8 , Amberlite IRA-96 , activated carbon , functionalized Amberlite XAD-7  and nanoparticles (TiO2) .
MnO2Resin is an inorganic, amphoteric resin dedicated for sorption of radium from water samples . This resin is characterized by high surface area, oxidizing properties and stability under acidic conditions. MnO2Resin was used primarily to extract radium from liquid waste by the uranium industry and to monitor marine waters for the presence of radioisotopes released from a nuclear reactor. The use of this sorbent is also mentioned in the literature for the preconcentration of lead, cadmium and chromium [21, 22, 23]. In natural systems (soils, water) manganese dioxide (MnO2) is a strong oxidizing agent which oxidizes Cr(III) to Cr(VI). The oxidation process depends upon concentration of soluble Cr, pH, surface area and the form of MnO2 . Chromium(III) oxidation by MnO2 has fast initial stage and then proceeds to the slower rate . Chung et al. studied the oxidation process of Cr(III) by three different Mn oxides: hausmanite, binessite and pyrolusite. Generally hausmanite, which has the highest Mn content, is a better oxidizing agent than binessite or pyrolusite . Moreover Cr(VI) is also sorbed on the MnO2 surface. Bhutani et al.  reported that the chromate ions have a strong affinity for the surface of manganese dioxide and suggested the sorption process takes place by a mechanism of ligand exchange. Gheju et al. reported that the sorption process of Cr(VI) on MnO2 can occur through two mechanisms: physical (non-specific adsorption, electrostatic interactions) and chemical (specific adsorption, chemical interactions). Non-specific adsorption by electrostatic interactions comes from the charge of the MnO2 surface. The charge of the MnO2 surface depends on the pH of the solutions, in acidic medium it is positively charged and in basic medium—negatively. Generally, the sorption of chromates or dichromates occurs rapidly from acidic solutions. Specific adsorption in the case of Cr(VI) takes places as a result of ionic sphere complexation .
In our previous paper we have developed a procedure based on radiochemical neutron activation analysis where the separation process of chromium was carried out using MnO2Resin. Application of radiochemical version of neutron activation analysis for chromium determination in biological samples has allowed for the elimination of the interferences and has resulted in the lower limit of detection . In this work we used Dowex 1X8 impregnated with saturated potassium permanganate solution for chromium separation and preconcentration. We examined resins with batch and column experiments. The results obtained for MnO2Resin and potassium permanganate impregnated Dowex 1X8 were compared. The results allowed to develop a procedure for the radiochemical determination of chromium in biological samples.
Chromium standards for irradiation were prepared by weighing aliquots of the standard solution in polyethylene capsules (Type “V’’ Vrije Universiteit, Biologisch Laboratorium, Netherlands) and evaporating to dryness before encapsulation. The following radioactive tracers were used: 134Cs (T1/2 = 2.06 y), 60Co (T1/2 = 5.27 years), 51Cr (T1/2 = 27.7 days), 46Sc (T1/2 = 83.8 days), 65Zn (T1/2 = 244 days). All tracers were prepared by neutron irradiation of spectrally pure oxides or salts (mostly nitrates) in a Polish nuclear reactor MARIA (neutron flux of 1014 cm−2 s−1). All reagents were of analytical grade. MnO2 Resin 100–200 mesh (Eichrom Technologies LLC) was used as received. High purity water, 18 MΩ cm from Milli QRG Ultra Pure Water System, Millipore Co., was used for the preparation of all solutions.
Preparation of manganese dioxide impregnated resin
A mass of 40 g of Dowex 1X8 [Cl−] resin (100–200 mesh), was washed twice with water from the Millipore system (reverse osmosis). The anion exchanger was then flooded with 40 mL of previously prepared saturated KMnO4 solution and stirred vigorously for 15 min. After that time the sample was centrifuged and the liquid from the sediment was poured off. The ionite impregnated with manganese groups was washed with 80 mL of distilled water of high purity, which was then centrifuged and washed away from the surface of the exchanger. This action was repeated three times. The resins prepared in this way were filtered and quantitatively transferred to a beaker. The exchanger was dried at 70 °C overnight and then gently mixed. The prepared resins were used in studies allowing for the determination of weight distribution coefficients.
Micro-analytical and analytical balances, Sartorius MC5 and Sartorius BP221S calibrated by the Central Office of Measures, were used to prepare standards, CRMs and samples for irradiation.
A high-pressure microwave system Anton Paar 3000 was applied to digest the samples.
Gamma-ray spectroscopic measurements were performed with the aid of a 255 cm3 HPGe well-type (Canberra) detector with associated electronics (resolution 2.15 keV for 1332 keV 60Co line, efficiency approximately 40% of a NaI (Tl) detector), coupled to the multichannel analyser and Genie-2000 spectroscopy software (Canberra).
Glass columns of I.D. 0.50 cm were used in column experiments.
Determination of distribution coefficient
In column experiments we used a previously calibrated column (h = 10 cm, r = 0.25 cm) filled with MnO2Resin or Dowex 1X8 resin impregnated with potassium permanganate. For the column experiment, we used the radioactive tracers 134Cs, 51Cr, 65Zn, 46Sc, 60Co. We prepared test and standard samples which contained the same radioactive tracers. Test samples were placed onto the column, and after the separation process measured with gamma spectrometry and compared with standard.
Results and discusion
As it can be seen in the Figs. 1, 2 and 3 sorption of chromium(VI) ions on MnO2Resin occurs preferably from dilute solutions of hydrochloric, nitric and sulphuric acids (0.01 mol/dm3). The highest mass distribution coefficient is observed in 0.01 mol/dm3 sulphuric acid. The sorption of chromium decreases when the concentration of acids increases. The mass distribution coefficient for other elements (Cs, Sc, Zn) in applied conditions were not high (excluding Co in 0.01 mol/dm3 HCl).
As it can be seen from Figs. 4, 5 and 6, sorption of chromium(VI) ions on impregnated Dowex 1X8 resin also occurs from diluted solutions of inorganic acids. The highest mass distribution coefficient for chromium was observed in 0.01 mol/dm3 HNO3. The sorption of chromium ions (similarly for MnO2Resin) decreases with increase of acids concentrations. The mass distribution coefficient for Cr(VI) on impregnated Dowex 1X8 resin is much smaller than for commercially available MnO2Resin. Probably the reason for this was heterogeneous planting of impregnated resin with manganese groups. The mass distribution coefficients for other examined elements were very small (Cs, Sc), but we observed sorption of cobalt in 0.01 mol/dm3 nitric acid. For Zn, the highest mass distribution coefficient was obtained in 2 mol/dm3 hydrochloric acid.
In Figs. 7 and 8 we show the separation process of chromium on MnO2Resin and impregnated Dowex 1X8 resin. As can be seen chromium is completely separated from other elements in both cases studied. However in the case of manganese dioxide impregnated resin the shape of the chromium elution curve suggests the possibility of the presence of two forms of chromium. This also confirms the recovery of chromium after the separation process onto the column. The process is quantitative only in the case of MnO2Resin and we have chosen this resin for further research on chromium determination in biological samples.
Chromium determination in biological samples after the separation with MnO2Resin
Determination of Cr in certified reference materials after separation with MnO2Resin
Cr certified value and its confidence limit (95%)
Cr Obtained result
X ± U (k = 2)
4.57 ± 0.18 mg kg−1
4.58 ± 0.18 mg kg−1
1.06 ± 0.34 mg kg−1
1.05 ± 0.04 mg kg−1
NIST SRM 1566a oyster tissue
1.43 ± 0.46 mg kg−1
1.41 ± 0.04 mg kg−1
MODAS M-3 herring tissue
919 ± 105 ng g−1
1030 ± 30 ng g−1
As it can be seen from Table 1, the results obtained for chromium after separation process using MnO2Resin, agree very well with certified values. The analysis of several certified references materials confirms the high accuracy of the developed procedure. The detection limit calculated with the Curie equation is 4.9 ng g−1 (20,000 s counting time) .
MnO2Resin and Dowex 1X8 impreganted with potassium permanganate resin was used for chromium preconcentration and separation from other elements. Chromium has a high affinity to both resins. However, the Kd values for chromium were higher in MnO2Resin than for Dowex 1X8 impregnated resin. The column experiments show that the separation process of chromium from other elements is selective but only in the case of MnO2Resin was quantitative and selective. The procedure of quantitative separation of chromium on MnO2Resin was checked by analysis of several certified references materials. The results show agreement with certified values, which confirms the accuracy of the developed procedure.
- 4.Chen S, Zhu L, Lu D, Cheng X, Zhan X (2010) Separation and chromium speciation by single-wall carbon nanotubes microcolumn and inductively coupled plasma mass spectrometry. Mirochem Acta 169:123–128Google Scholar
- 5.Pazos-Capeáns P, Barciela-Alons MC, Bermejo-Barrera A, Bermejo-Barrera P, Fisher A, Hill SJ (2006) On-line sequential determination of Cr(III) and Cr(VI) with selective elution of solid extracts using an alumina column. At. Spectr. 27(4):107–116Google Scholar
- 7.Linos A, Petralias A, Christophi CA, Chrisotoforidou E, Kourouton P, Stodilis M, Veloudaki A, Tzala E, Makris KC, Karagas MR (2011) Oral ingestion of hexavalent chromium through drinking water and cancer mortality in an industrial area of Greece–an ecological study. Environ Health 10:50–58CrossRefGoogle Scholar
- 8.US EPA (United States Environmental Protection Agency) (2004) Edition of the drinking water standards and health advisories, EPA 882-R-04-005, Office of Water U.S. Environmental Protection Agency, Washington, DC, WinterGoogle Scholar
- 9.EPA’s (2008) Report on the environment. http://www.epa.gov/roe
- 10.(2008) Guidelines for drinking water quality, 3rd edn, vol 1, Recommendations, WHO, GenevaGoogle Scholar
- 11.(2003) Chromium in drinking water, background document for development of WHO, guidelines for drinking water quality, WHO/SDE/WSH/03.04/4, WHO, GenevaGoogle Scholar
- 12.Council directive of 3 November 1998 on the quality of water intended for human consumption, OJEU, L 330/32,5.12/98Google Scholar
- 15.Lopez-Guerro MM, Verreda AE, Cano Pavon JM, Siles Coredo MT, Garcia de Torres A (2012) On-line preconcentration using chelating and ion-exchange minicolumns for the speciation of chromium(III) and chromium(VI) and their quantitative determination in natural waters by inductively coupled plasma mass spectrometry. JAAS 27:682–688Google Scholar
- 18.Sadia M (2017) Indirect speciation of Cr(VI) and Cr(III) in water and food samples using newly synthesized Amberlite XAD-7 functionalized resin. J Biodivers Environ Sci 10(1):36–48Google Scholar
- 26.Chung JB, Zasoski RJ, Lim SU (1994) Kinetics of chromium (III) oxidation by various manganese oxides. Agric Chem Biotechnol 37:414–420Google Scholar
Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.