Matrix-type certified reference materials for quality control of metal determination from solid environmental and vegetation samples

In the context of monitoring environmental factors, metals are one of the major analytical components. Applying appropriate determination methods and obtaining accurate results is a requirement imposed on environmental laboratories that perform quality control of water, soil, waste or vegetation. This study presents some examples of certified reference materials for quality control of the results of toxic metal determination from solid environmental and vegetation samples. The analyzed and verified metals were As, Cd, Cr, Cu, Ni, Pb and Zn. The pre-treatment of the samples, the determination methods of metals and the obtained results are also presented. Inductively Coupled Plasma Optical Emission Spectrometry (ICP-EOS) and Inductively Coupled Plasma Mass Spectrometry (ICP-MS) techniques are suitable for low metal concentrations, while ICP-EOS and Flame Atomic Absorption Spectrometry (FAAS) methods can be used at high concentrations

Different routes of MgAl–LDH synthesis for tailoring the adsorption of Pb(II) pollutant from water

In this study, new adsorbents based on MgAl–LDHs were synthesized using combined precipitation (co-precipitation) route by modifying temperature and ageing time synthesis parameters, thus tailoring the adsorption capacity of Pb(II) ions from water. The synthesized materials were characterized by SEM, FTIR, XRD and $\text{N}_2$ adsorption–desorption techniques, highlighting the specific lamellar structure of layered double hydroxides (LDHs), as well as the functional groups present on the adsorbent’s surface. The maximum adsorption capacity for Pb(II) ions was 1151.97 mg/g for the MgAl–LDH synthesized at 55 °C and aged for 24 h. Sorption of Pb(II) ions occurs not only through co-precipitation in the form of characteristic compounds, $\text{Pb(OH)}_2$, $\text{PbCO}_3$ or $\text{Pb}_3(\text{CO}_3)_2(\text{OH})_2$, but also by complexation with surface hydroxyl groups

Different routes of MgAl–LDH synthesis for tailoring the adsorption of Pb(II) pollutant from water

In this study, new adsorbents based on MgAl–LDHs were synthesized using combined precipitation (co-precipitation) route by modifying temperature and ageing time synthesis parameters, thus tailoring the adsorption capacity of Pb(II) ions from water. The synthesized materials were characterized by SEM, FTIR, XRD and $\text{N}_2$ adsorption–desorption techniques, highlighting the specific lamellar structure of layered double hydroxides (LDHs), as well as the functional groups present on the adsorbent’s surface. The maximum adsorption capacity for Pb(II) ions was 1151.97 mg/g for the MgAl–LDH synthesized at 55 °C and aged for 24 h. Sorption of Pb(II) ions occurs not only through co-precipitation in the form of characteristic compounds, $\text{Pb(OH)}_2$, $\text{PbCO}_3$ or $\text{Pb}_3(\text{CO}_3)_2(\text{OH})_2$, but also by complexation with surface hydroxyl groups

Optimized hybrid nanospheres immobilizing Rhizomucor miehei lipase for chiral biotransformation

[EN] In this study, the immobilization of Rhizomucor miehei lipase into hybrid nanospheres containing a liposomal core was reported. Organic internal liposomal enzyme phase was protected by inorganic silica matrix, obtained with and without surfactant, that stabilizes the internal organic phase and isolates and protects the bioactive molecules. The optimized heterogeneous catalyst thus prepared was used for enantioselective esterification of (R,S)-ibuprofen. The influence of several catalytic parameters on the activity of hybrid nanospheres (type of solvent, nature of the alcohol, reaction temperature, etc.,) was investigated. The heterogeneous biocatalysts best performed at 37 degrees C, using isooctane as solvent and 1-propanol as alcohol (with ester yield ranging between 78 and 93%). High activity and stability (up to nine reaction cycles) of enzyme-immobilized hybrid nanospheres, with respect to the free form, were observed. R. miehei lipase, both in its free and immobilized forms, reacts only with the S(+) enantiomer of (R,S)-ibuprofen, in all the tested reaction conditions. (C) 2015 Elsevier Ltd. All rights reserved.The authors thank the financial support from Consolider-Ingenio MULTICAT CSD2009-00050, MAT2014-52085-C2-1-P, and Severo Ochoa Excellence Program SEV-2012-0267.Verri, F.; Díaz Morales, UM.; Macario, A.; Corma Canós, A.; Giordano, G. (2016). Optimized hybrid nanospheres immobilizing Rhizomucor miehei lipase for chiral biotransformation. Process Biochemistry. 51(2):240-248. https://doi.org/10.1016/j.procbio.2015.11.020S24024851

Siderophore-based detection of Fe(iii) and microbial pathogens

Siderophores are low-molecular-weight iron chelators that are produced and exported by bacteria, fungi and plants during periods of nutrient deprivation. The structures, biosynthetic logic, and coordination chemistry of these molecules have fascinated chemists for decades. Studies of such fundamental phenomena guide the use of siderophores and siderophore conjugates in a variety of medicinal applications that include iron-chelation therapies and drug delivery. Sensing applications constitute another important facet of siderophore-based technologies. The high affinities of siderophores for both ferric ions and siderophore receptors, proteins expressed on the cell surface that are required for ferric siderophore import, indicate that these small molecules may be employed for the selective capture of metal ions, proteins, and live bacteria. This minireview summaries progress in methods that utilize native bacterial and fungal siderophore scaffolds for the detection of Fe(III) or microbial pathogens.Massachusetts Institute of Technology. Dept. of Chemistr

Spectrophotometric determination of Ru(III) using rhodanine

1019-1020A simple and direct spectrophotometric method using 2-thion-thiazolid-4-one has been developed for determination of Ru (III).Molar absorptivity and Sandell' s sensitivity are calculated to be 6.5555×103 L mol-1 cm-1 and 0.0154 μg cm-2 respectively. The effect of various parameters including time, pH and volume of reagent has been studied. The Beer's law is obeyed over the range 0.202-6.873 μg of Ru(III). The method has been applied for the determination of Ru(III) in various synthetic and real samples

Adsorptive removal of cadmium and copper from water by mesoporous silica functionalized with N-(aminothioxomethyl)-2-thiophen carboxamide

International audienceCopper and cadmium ions were removed from aqueous solutions by adsorption onto a new organic-inorganic hybrid material. N-(aminothioxomethyl)-2-thiophen carboxamide (TAC) was covalently anchored on SBA-15 mesoporous silica. Various characterization techniques [X-ray diffraction, nitrogen adsorption-desorption, thermogravimetric analysis, 29Si, 13C nuclear magnetic resonance (NMR), and Fourier-transform infrared (FTIR) spectroscopy] have proved that the organic ligand was successfully anchored and the ordering of the inorganic support was preserved during the chemical modifications. Metal cations in aqueous solution were adsorbed onto this material with multichelating atoms by a complexation mechanism. Adsorption capacity for the divalent copper and cadmium cations were 0.74 and 0.21 mmol g−1, respectively. Cu(II) was selectively eliminated from contaminated water with Cu(II) and Cd(II). TAC-functionalized silica sorbent presented a good regeneration capacity without significantly losing its adsorption capacity and could be used for the development of an in-flow wastewater purification technology

A new mesoporous Micelle-Templated Silica route for enzyme encapsulation

International audienc