Determination of carotenoids in spear shrimp shells (Parapenaeopsis hardwickii) by liquid chromatography

The objectives of this study were to develop a high-performance liquid chromatography method for analysis of carotenoids in spear shrimp shells (Parapenaeopsis hardwickii) and to compare the extraction efficiency of carotenoids by supercritical carbon dioxide (SCD) and solvents. Results showed that the most appropriate HPLC method was accomplished by employing a Cosmosil 5C18-AR-II column and a mobile phase of methanol-dichloromethane-acetonitrile (90:5:5, v/v/v) (A) and water (100%) (B) with the following gradient elution: 92% A and 8% B in the beginning, decreased to 4% B in 9.5 min, 1% B in 26 min, 0% B in 35 min, maintained for 25 min, and returned to 92% A and 8% B in 61 min. All-trans-astaxanthin and its two cis isomers, as well as five astaxanthin monoesters and 11 diesters were resolved within 60 min with a flow rate at 2 mL/min and detection at 480 nm. Astaxanthin diesters were found to contain 12 fatty acids, of which palmitic acid and stearic acid constituted a large portion, whereas astaxanthin monoesters were found to contain 10 fatty acids with arachidonic acid dominating. Solvent extraction could generate a higher content of trans-astaxanthin and astaxanthin esters, while SCD extraction could produce greater levels of 9-cis-astaxanthin and 13-cis-astaxanthin.     

Separation and preconcentration of Cd(II), Cu(II), Ni(II), and Pb(II) in water and food samples using Amberlite XAD-2 functionalized with 3-(2-nitrophenyl)-1H-1,2,4-triazole-5(4H)-thione and determination by inductively coupled plasma-atomic emission spectrometry

A separation and preconcentration procedure was developed for the determination of trace amounts of Cd(II), Cu(II), Ni(II), and Pb(II) in water and food samples using Amberlite XAD-2 fuctionalized with a new chelating ligand, 3-(2-nitrophenyl)-1H-1,2,4-triazole-5(4H)-thione (Amberlite XAD-2-NPTT). The chelating resin was characterized by Fourier transform infrared spectroscopy (FT-IR) and used as a solid sorbent for enrichment of analytes from samples. The sorbed elements were subsequently eluted with 10 mL of 1.0 M HNO(3), and the eluates were analyzed by inductively coupled plasma-atomic emission spectrometry. The influences of the analytical parameters including pH, amount of adsorbent, eluent type and volume, flow rate of the sample solution, volume of the sample solution, and effect of matrix on the preconcentration of metal ions have been studied. The optimum pH for the sorption of four metal ions was about 6.0. The limits of detection were found to be 0.22, 0.18, 0.20, and 0.16 μg L(-1) for Cd(II), Cu(II), Ni(II), and Pb(II), respectively, with a preconcentration factor 60. The proposed method was applied successfully for the determination of metal ions in water and food samples.     

Metal-Metal Interactions in Biological Systems. Part VI. Effect of Some Metal ions on Mortality,Pathogenicity and Reproductivity of Steinernema carpocapsae and Heterorhabditis bacteriophora Entomopathogenic Nematodes under Laboratory Conditions

Effect of Li, Al, Cd, Cu(II), Mn(II), Pb(II), Se(IV) and Zn on entomopathogenic nematodes S. carpocapsae and H. bacteriophora mortality, pathogenicity, and productivity was studied under laboratory conditions. These ions were administered as the sole ions as well as in the Li-Al, Li-Cd, Li-Cu(II), Li-Mn(II), Li-Pb(II), Li-Se(IV) and Li-Zn pairs. Lithium as the sole acting ion exhibited a weak lethal effect on the nematodes. In combinations with other metal ions under study lithium used to inhibit their harmful effects.     

Metal-metal interactions in biological systems. Part IV. Freshwater snail Bulinus globosus

The toxicity against title snails of all Al, Cd, Co(II), Cr(III), Cu(II), Fe (III), Mg, Mn(II), Mo(VI), Ni(II), Pb(II), Se(VI), V(V) and Zn ions was checked in 96 h tests in the water of Kariba Lake. Based on the mortality — concentration relationship the toxicity order of the above ions against Bulinus globosus is Cu(II) > Ni(II) > Cd > Pb(II) > Zn > Al > V(V)> Cr(III)> Se(VI) > Fe(III) =Co(II)> Mn(II) > Mg > Mo(VI). Only Mg, Pb(II), Cu(II), Cd, Zn and Ni(II) ions are harmful to these snails as their mortality is observed at the naturally occuring concentrations. Other metal ions cause lethality at naturally unrealistic concentrations. The following pairs of metal ions were also checked for mutual interactions: Cd-Al, Cd-Co, Cd-Cr, Cd-Cu, Cd-Fe, Cd-Mg, Cd-Mn, Cd-Mo, Cd-Ni, Cd-Pb, Cd-Se, Cd-V, Cd-Zn, Cu-Al, Cu-Co, Cu-Cr, Cu-Fe, Cu-Mg, Cu-Mn, Cu-Mo, Cu-Ni, Cu-Pb, Cu-Se, Cu-V, Cu-Zn, Ni-Al, Ni-Co, Ni-Cr, Ni-Fe, Ni-Mg, Ni-Mn, Ni-Mo, Ni-Pb, Ni-Se, Ni-V, Ni-Zn, Pb-Al, Pb-Co, Pb-Cr, Pb-Fe, Pb-Mg, Pb-Mn, Pb-Mo, Pb-Se, Pb-V, Pb-Zn, Zn-Al, Zn-Co, Zn-Cr, Zn-Fe, Zn-Mg, Zn-Mn, Zn-Mo, Zn-Se, Zn-V. Synergism and antagonism were several times observed in various combinations of ions. The effect of metal-metal interactions on an accumulation of those metals in the flesh and shells of snails was also observed and measured.     

Chemically Modified Silica Gel with N-(2-aminoethyl)-Salicylaldimine for Simultaneous Solid Phase Extraction and Preconcentration of Cu(II), Ni(II), Cd(II) and Zn(II) in waters

In this study, N-(2-aminoethyl)salicylaldimine bonded silica gel was synthesized and characterized using Fourier transform infrared and C, H, N elemental analysis. The analytical conditions such as the pH and volume of the solution, flow rates of the sample solution and the type of eluent to achieve the simultaneous preconcentration of Cu(II), Ni(II), Cd(II) and Zn(II) were optimised using the modified silica gel loaded column using a solid phase extraction technique. Samples (50?C500?ml) containing metal ions at optimal pH of 8 were passed through the column filled with the modified silica gel at 7?ml min^?1 and then elution was achieved using 5?ml of 0.25?M HCl. The concentrations of metal ions in the eluates were determined using flame atomic absorption spectrometry (FAAS). The effects of matrix ions were also studied and none of the major ions interfered to the proposed method. The accuracy of the developed method was validated using a certified reference water sample (Ontario Lake water, NWTMDA-54.4). The method was successfully applied to the analysis of various natural water samples. The adsorption capacities of the modified silica gel for Cu(II), Ni(II), Cd(II) and Zn(II) ions were determined and found to be 0.332, 0.261, 0.130 and 0.375?mmol g^?1, respectively.     

Biosorption of Toxic Heavy Metal Ions from Water Environment Using Honeycomb Biomass—An Industrial Waste Material

This paper examined the ability of honeycomb biomass (HC), a by-product of the honey industry, to remove Pb(II), Cd(II), Cu(II), and Ni(II) ions from aqueous solutions. The equilibrium adsorptive quantity was determined as a function of the solution pH, amount of biomass, contact time, and initial metal ion concentration in a batch biosorption technique. Biosorbent was characterized by Fourier transform infrared (FTIR), scanning electron microscopy with energy-dispersive X-ray, and X-ray diffraction studies. FTIR spectral analysis confirmed the coordination of metals with hydroxyl, carbonyl, and carboxyl functional groups present in the HC. The metals uptake by HC was rapid, and the equilibrium time was 40?min at constant temperature and pH. Sorption kinetics followed a nonlinear pseudo-second-order model. Isotherm experimental data were fitted to Langmuir, Freundlich, Dubinin?CRadushkevich, and Temkin isotherm models in nonlinear forms. The mechanism of metal sorption by HC gave good fits for Langmuir model, and the affinity order of the biosorbent for four heavy metals was Pb(II)>Cd(II)>Cu(II)>Ni(II). The thermodynamic studies for the present biosorption process were performed by determining the values of ??G°, ??H°, and ??S°, and it was observed that biosorption process is endothermic and spontaneous. This work provides an efficient and easily available environmental friendly honeycomb biomass as an attractive option for removing heavy metal ions from water and wastewater.     

Effect of metal ions under laboratory conditions on the entomopathogenic Steinernema carpocapsae (Rhabditida: Steinernematidae)

The effects of sixteen metal ions: Al, Cd, Co(II), Cr(III), Cr(VI), Cu(II), Fe(III), Li, Mg, Mn(H), Mo(VI), Ni(II), Pb(II), Se(IV), V(V), and Zn on the mortality and infectivity of Steinernema carpocapsae were observed in 96 hour laboratory tests. All ions except Cu(II), Pb(II), and Zn even at naturally unrealistic concentrations did not cause the mortality of S. carpocapsae. However, such treatment lowered infectivity of nematodes with respect to wax moth caterpillars, Galleria mellonella.     

Effect of Metal Ions on the Entomopathogenic Nematode Heterorhabditis Bacteriophora Poinar (Nematoda: Heterohabditidae) Under Laboratory Conditions

The effect of sixteen metal ions: Al, Cd, Co(II), Cr(III), Cr(VI), Cu(II), Fe(III), Li, Mg, Mn(II), Mo(VI), Ni(II), Pb(II), Se(IV), V(V), and Zn on the mortality and infectivity ofHeterorhabditis bacteriophora were observed over a 96 hr period. All ions except Pb(II) even at naturally unrealistic concentrations did not cause the mortality of the nematodes. A weak vitalizing effect could eventually be observed with Mn(II), Mg, Fe(III) and Ni(II) (Table 1). However, such treatment generally lowered infectivity of the nematodes with respect to wax moth caterpillars.Galleria mellonella. This effect was particularly significant with Ni(II) and Pb(II).     

Metal-Metal Interactions in Biological Systems. Part V. Steinernema Carpocapsae (Steinernematidae) and Heterorhabditis Bacteriophora (Heterorhabditidae) Entomopathogenic Nematodes

In spite of a lack of acute toxicity of single metal ions, in 96 hour laboratory tests there was a long term toxicity againstS. carpocapsae andH. bacteriophora nematodes. The 96 hour laboratory tests were carried out in order to prove possible synergistic and antagonistic interactions between pairs of metal ions. Thus, the pairs of ions were arranged from each of Al, Cd, Co(II), Cr(III), Cr(VI), Cu(II), Fe(III), Li, Mo(VI), Ni(II), Sc(IV), V(V) and Zn on one side and Mn(II) and Mg on the other. Mn(II) and Mg ions considerably reduced the nematode mortality and increased their infectivity againstGalleria mellonella caterpillars.     

The effect of waste water treatment on river metal concentrations: removal or enrichment?

Purpose

Discharge of untreated domestic and industrial waste in many European rivers resulted in low oxygen concentrations and contamination with trace metals, often concentrated in sediments. Under these anoxic conditions, the formation of insoluble metal sulfides is known to reduce metal availability. Nowadays, implementation of waste water treatment plants results in increasing surface water oxygen concentrations. Under these conditions, sediments can be turned from a trace metal sink into a trace metal source.

Materials and methods

In an ex situ experiment with metal contaminated sediment, we investigated the effect of surface water aeration on sediment metal sulfide (acid volatile sulfides (AVS)) concentrations and sediment metal release to the surface water. These results were compared with long-term field data, where surface water oxygen and metal concentrations, before and after the implementation of a waste water treatment plant, were compared.

Results and discussion

Aeration of surface water in the experimental setup resulted in a decrease of sediment AVS concentrations due to sulfide oxidation. Metals, known to precipitate with these sulfides, became more mobile and increasing dissolved metal (arsenic (As), cadmium (Cd), copper (Cu)) concentrations in the surface water were observed. Contrary to As, Cd, or Cu, manganese (Mn) surface water concentrations decreased in the aerated treatment. Mn ions will precipitate and accumulate in the sediment as Mn oxides under the oxic conditions. Field data, however, demonstrated a decrease of all total metal surface water concentrations with increasing oxygen concentrations following the implementation of the waste water treatment plant.

Conclusions

The gradual decrease in surface water metal concentrations in the river before the treatment started and the removal of metals in the waste water treatment process could not be countered by an increase in metal flux from the sediment as observed in the experiment.     

Comparison of Heavy Metal Adsorptions by Thai Kaolin and Ballclay

The adsorption characteristics of heavy metals: cadmium(II), chromium(III), copper(II), nickel(II), lead(II), and zinc(II) ions by kaolin (kaolinite) and ballclay (illite) from Thailand were studied. This research was focussed on the pH, adsorption isotherms of single-metal solutions at 30–60 °C by batch experiments, and on ion selectivityin mixed and binary combination solutions. It was found that, except Ni, metal adsorption increased with increased pH of the solutions and their adsorption followed both Langmuir and Freundlich isotherms. Adsorption of metals in the mixture solutions by kaolin was: Cr > Zn > Cu ≈ Cd ≈ Ni > Pb, and for ballclay was: Cr > Zn > Cu > Cd ≈ Pb > Ni. The adsorption of metals was endothermic, with the exception of Cd, Pb and Zn for kaolin, Cu and Zn for ballclay. Kaolin and ballclay exhibited relatively hard Lewis base adsorption site. The presence of other metals may reduce or promote the adsorption of heavy metals. The presence of Cr³⁺ induced the greatest reduction of metal adsorptiononto kaolin, as did the presence of Cu²⁺ for ballclay.     

A Comparative Study of Batch and Continuous Bulk Liquid Membranes in the Removal and Recovery of Cu(II) Ions from Wastewater

The aim of this work was to compare the performance between a batch bulk liquid membrane (BBLM) and a continuous bulk liquid membrane (CBLM) in the removal and recovery of Cu(II) ions from wastewater. Effects of operating parameters affecting the resistance of Cu(II) ion transfer such as stirring speeds of phases in BBLM, flow rates of phases through CBLM and operating temperature of both BBLM and CBLM on the removal and recovery of Cu(II) ions from aqueous solutions were explored. The variations in Reynolds number and thickness of boundary layer of all phases with stirring speed in BBLM and with flow rate in CBLM, as well as changes in the viscosity of membrane phase with temperature in both BBLM and CBLM were also investigated. A comparison of performance between BBLM and CBLM in the treatment of real industrial wastewater was also conducted and evaluated. It was found that BBLM achieved higher extraction (removal) and stripping (recovery) of Cu(II) ions of up to 16% than CBLM over the range of experimental conditions studied. Both BBLM and CBLM were found to remove and recover Cu(II) ions effectively from real industrial wastewater.     

Study of Ni(II), Cu(II), Pb(II), and Zn(II) Removal Using Sludge and Minerals Followed by MF/UF

This work examined the removal of heavy metals in a system consisting of ultrafiltration (UF) or microfiltration (MF) membranes combined with sludge and minerals. The metals under examination were Ni(II), Cu(II), Pb(II), and Zn(II), while the system performance was investigated with respect to several operating parameters. Metal removal was achieved through various processes including chemical precipitation, biosorption, adsorption, ion exchange, and finally retention of the metals by the membranes. The pH had a profound effect on metal removal, as the alkaline environment favored the metal removal process. The use of sludge resulted in increased levels of metal uptake which was further enhanced with the addition of minerals. The metal removal mechanisms depended on the pH, the metal, and mineral type. The combined sludge?Cmineral?CUF system could effectively remove metal ions at an alkaline environment (pH?=?8), meeting the US EPA recommended long-term reuse limits of lead and copper and the short-term reuse limits of nickel and zinc for irrigation purposes, provided that specific mineral dosages were added.     

水稻子实对不同形态重金属的累积差异及其影响因素分析

在分析成都平原核心区土壤重金属(Cd、Cr、Pb、Cu、Zn)全量、各形态含量及相应点位种植的水稻子实重金属含量的基础上,通过统计分析、空间插值及线性回归方程的模拟,研究了土壤Cd、Cr、Pb、Cu、Zn全量的空间分布状况、各形态重金属含量统计特征,以及水稻子实对重金属各形态的累积差异及其影响因素。结果表明,成都平原水稻土重金属污染较轻,除Cd外,均低于国家土壤环境质量二级标准。土壤中重金属的可交换态含量均较低,Cd主要以铁锰氧化态存在,Cr、Cu、Zn、Pb主要以残渣态存在。水稻子实对5种重金属的累积效应顺序为:Cd>Zn>Cu>Pb>Cr。与水稻重金属累积关系密切的重金属活性形态(可交换态、碳酸盐结合态、铁锰氧化物结合态和有机物结合态)主要有:Cd的碳酸盐结合态、Cr的可交换态、Pb的有机物结合态和Cu的碳酸盐结合态含量;Zn各活性形态对水稻子实含量的影响不明显。土壤理化性质对不同活性形态重金属元素的影响效应各不相同。活性态Cd主要受有机质、pH和容重的影响;活性态Cr与pH、有机质、CEC和容重密切相关;活性态Pb与有机质、容重、中细粉粒、砂粒等均有密切的关系;Cu的活性主要受粘粒、有机质含量的影响;Zn的有效性主要受pH、有机质、砂粒、容重的影响。总的看来,对土壤Cd、Cr、Pb、Cu、Zn各活性形态含量影响效应较强的是有机质、pH、容重,而与土壤吸附性能密切相关的颗粒组成、CEC的影响不甚明显。     

Comparison of thermal and chemical stability of Cu–humic complexes

Purpose

The purpose of this study was to investigate relationships between chemical and thermal stabilities of Cu–humic complexes. The study of the chemical stability was based on pedological methods used for the determination of the bond strength of metal ions in soils by chemical leaching agents. The samples with various contents of the Cu(II) ions and their bond strength were put to the thermal analysis in order to correlate their thermo-oxidative behavior with their stability determined by leaching.

Materials and methods

The humic acid was extracted from the South-Moravian lignite by standard alkaline extraction. The humic sample was used in two different forms: as the solid powder and as the hydrogel prepared by the acidic precipitation of humate. Six various concentrations of copper(II) solutions were used for the complexation of the humic powder and the hydrogel, in order to study the influence of their initial concentration on both the determined stabilities of the prepared complexes. Their chemical stability was assessed in terms of the Cu(II) ions release from the humic acid structure into two different extraction agents (MgCl₂ and HCl solutions). Their thermo-oxidative behavior was investigated employing the thermogravimetry.

Results and discussion

The complexation capacity of the humic hydrogel was higher in comparison with the humic powder. The amounts extractable from the Cu–humic complexes by the used leaching agents are higher for the humic powder, which shows on the lower chemical stability. The thermal degradation of the prepared complexes proceeds in several steps and this character remains also after the removal of the mobile and the ion-exchangeable fractions by the MgCl₂. The elimination of these fractions as well as the extraction of the strongly bound Cu(II) ions shift the thermal degradation to higher temperatures. The incombustible residue increases with the Cu(II) content in the complexes except for the samples extracted by the HCl.

Conclusions

The form of humic sample used for the preparation of the Cu–humic complexes influences both the chemical stability and the thermal one. The main reason is probably a better accessibility of the functional groups in the humic gel, which enables forming stronger binding copper(II) ions. The results showed that the thermal and chemical stabilities are closely related, which corresponds with the shift of the thermal degradation to higher temperatures after removing the less stable fractions from the humic complexes.     

Surface Modification of Sporopollenin with Calixarene Derivative

In this study, p-tert-butylcalix[4]-aza-crown (CAC) immobilized sporopollenin (Sp) was used as a sorbent for the removal of Cu(II), Pb(II) and Zn(II) from aqueous media. Sporopollenin was firstly functionalized with 3-chloropropyltrimethoxysilane (CPTS) in order to obtain chloro-sporopollenin (Sp-Cl). The Sp-Cl was reacted subsequently with CAC yielding CAC-bonded sporopollenin (Sp-Cl-CAC). The new sorbent was characterized by infrared spectroscopy (FTIR), thermal analysis (TG/DTG) and scanning electron microscopy (SEM). The sorption properties of modified sorbent (Sp-Cl-CAC) are also investigated. The optimum pH values for the separation of metal ions from aqueous solution onto Sp-Cl-CAC were 5.0 for Pb(II) and Cu(II) and 5.5 for Zn(II). The maximum sorption capacities for Cu(II), Pb(II) and Zn(II) were 0.07 (4.44?mg?g^?1), 0.07 (4.58?mg?g^?1) and 0.14 (29.00?mg?g^?1) mmol?g^?1, respectively. Sorption thermodynamic parameters of such as free energy (?G ^o), enthalpy (?H ^o), and entropy (?S ^o) were evaluated.     

Reactions of fulvic acid with metal ions

Fulvic acid is a water-soluble humic material that occurs widely in soils and waters and that tends to form water-soluble and water-insoluble complexes with a variety of metal ions, some of which are toxic. This paper presents information on the conditions under which the different types of FA-metal complexes are formed. The solubility in water, separately and after mixing, of FA (2 to 30 mg/100 ml) and eleven metal ions (Fe(III), Al, Cr(III), Pb, Cu, Hg(II), Zn, Ni, Co, Cd and Mn; 1 × 10^?5 moles of each metal ion) was investigated over the pH range 4 to 9. After mixing, the solubility of the components was significantly affected by pH only when less than 20 mg of FA was present. As the systems became richer in FA (22 to 30 mg), most of the metal ions remained in the aqueous phase, likely due to the formation of FA-metal complexes, inhibiting the formation of metal hydroxides. The order in which the eleven metal ions tended to form water-insoluble FA-metal complexes depended on the pH. At pH 6 it was: Fe = Cr = Al > Pb = Cu > Hg > Zn = Ni = Co = Cd = Mn. This order appeared to correlate with the valence, 1st hydrolysis constants and effective hydrated ionic diameters of the metal ions. In general, FA/metals weight ratios of > 2 favored the formation of water-soluble FA-metal complexes; at lower ratios, water-insoluble complexes, which could accumulate in soils and sediments, were formed.     

Effects of fresh and degraded dissolved organic matter derived from maize straw on copper sorption onto farmland loess

Purpose

The nature of dissolved organic matter (DOM) strongly influences heavy metal sorption onto soil. However, the constituents and structures of DOM change continuously as DOM is subjected to microbial decomposition and photodegradation at natural field scales. Thus, this study was designed to explore the effects of chemical changes of DOM on heavy metal sorption onto farmland soil in natural degradation.

Materials and methods

Fresh DOM (FDOM) and degraded DOM (DDOM) both were extracted from the straw of maize which was extensively planted in Loess Plateau, China. The characteristics of DOM were determined by Fourier transform infrared spectroscopy (FTIR), elemental analysis, excitation-emission matrix (EEM) fluorescence spectra, UV-visible spectra (UV-vis), nuclear magnetic resonance (NMR), and molecular weight analysis. Farmland loess soil in Loess Plateau and heavy metal Cu(II) which can easily form a complex with DOM in soil were employed to investigate the effects of DOM dynamic changes on Cu(II) sorption onto loess through batch tests.

Results and discussion

Compared with FDOM, DDOM changed significantly in composition including oxygen content, functional group species, aromatic properties, and molecular weight distribution. Oxygen content, aromaticity, and low-molecular-weight fraction (<3 kDa) decreased while aromatic substitution and high-molecular-weight fraction (>10 kDa) increased for DDOM. For these changes, the effects of FDOM and DDOM on heavy metal Cu(II) sorption onto loess were significantly different due to DOM-Cu(II) binding ability varied with FDOM degradation. FDOM promoted Cu(II) sorption onto loess at Cu(II) concentration below 400 mg l^?1 while inhibited above 400 mg l^?1, but DDOM always showed inhibition effects on Cu(II) sorption onto loess. Moreover, both the promotion and inhibition effects depended mainly on the initial concentrations and pH values of FDOM and DDOM.

Conclusions

The results of the present study demonstrate that chemical characteristics of FDOM and DDOM are greatly diverse in components, functional group species, molecular weight distribution, etc. although they are from the same source. The apparent differences can explain their distinct effects on copper sorption onto loess soil. Hence, future researches are supposed to focus on the dynamic changes of DOMs when evaluating their influence on heavy metals environmental behaviors under actual conditions.

     

Metal complexation by the peptide-bound maillard reaction products N(epsilon)-fructoselysine and N(epsilon)-carboxymethyllysine

Although the Maillard reaction between proteins and carbohydrates is of central importance for food processing and in vivo processes, only little is known about changes of the metal-binding properties induced by protein glycation. The purpose of this study was to examine the complex formation of the quantitatively important peptide-bound Maillard reaction products (MRPs) N(epsilon)-fructoselysine and N(epsilon)-carboxymethyllysine with the biologically relevant metal ions copper(II) and zinc(II). The MRPs were synthesized as the N(alpha)-hippuryllysine derivatives in order to block the coordination function of the alpha-amino group. Stability constant measurements were performed in aqueous solution using pH potentiometry. N(alpha)-Hippuryl-N(epsilon)-fructoselysine forms moderate Cu(II) complexes (Log(10) K(1) = 5.8; Log(10) K(2) = 4.0) but fails to form any complexes with Zn(II). N(alpha)-Hippuryl-N(epsilon)-carboxymethyllysine gives slightly stronger complexes with Cu(II) (Log(10) K(1) = 7.3; Log(10) K(2) = 6.3), but again no complexation with Zn(II) was observed. These results show that post-translational modification of proteins by carbohydrates leads to the formation of new coordination centers for metal ions within a protein chain. Further studies are necessary to clarify the consequences of this phenomenon in terms of protein quality and physiological processes.