The matrix effects in MIP OES arising in the presence of elements with E_ion 5.13–9.39 eV (Na, Cu, Pb, Cd, Zn) depending on the concentration, nebulization flow rate, and plasma power were studied.

Four new metal–organic frameworks based on cobalt(II) salts and 1,4-diazabicyclo[2.2.2]octane N,N’-dioxide (odabco) were obtained. Their crystallographic formulae are [Co₃(odabco)₂(OAc)₆] (1, OAc⁻ = acetate), [Co(H₂O)₂(HCOO)₂]·odabco (2), [Co₂(H₂O)(NO₃)(odabco)₅](NO₃)₃·3.65H₂O (3), and [Co₂(DMF)₂(odabco)₄](NO₃)₄·3H₂O (4; DMF = N,N-dimethylformamide). Crystal structures of 1–4 were determined by single-crystal X-ray crystallography. Coordination polymer 1 comprises binuclear and mononuclear metal–acetate blocks alternating within uncharged one-dimensional chains, in which odabco acts as a bridging ligand. A layered Co(II) formate 2 contains odabco only as guest molecules located in the interlayer space. Layered compound 3 and three-dimensional 4 have cationic coordination frameworks with 26% and 34% specific void volumes, respectively, unveiling high structural diversity of Co(II)-odabco MOFs based on quite a rare aliphatic moiety. Magnetization measurements were performed for 1, 3, and 4 and the obtained data were interpreted on the basis of their crystal structures. A strong (J/k_B~100 K) antiferromagnetic coupling was found within binuclear metal blocks in 1. Ion exchange experiments revealed a considerable iodide uptake by 3 resulting in an up to 75% guest nitrate substitution within the voids of a coordination framework, found by capillary zone electrophoresis data and confirmed by single-crystal XRD. A preservation of 3 crystallinity during the exchange allowed for the guest I⁻ positions within a new adduct with the formula [Co₂(H₂O)(NO₃)(odabco)₅]I₂(NO₃)·1.85H₂O (3-I) to be successfully determined and the odabco aliphatic core to be revealed as a main adsorption center for quite large and easily polarizable iodide anions. In summary, this work presents a comprehensive study for a series of 1,4-diazabicyclo[2.2.2]octane N,N’-dioxide-based MOFs of cobalt(II) within the framework of magnetic properties and reports the first example of anion exchange in odabco-based coordination networks, supported by direct X-ray structural data. The reported results unveil promising applications of such frameworks bearing ligands with an aliphatic core in the diverse structural design of selective adsorbents and other types of functional materials.

The effect of matrix elements (Na, In, Bi, Zn, Cu) and nitric and hydrochloric acids on the analytical signals of impurity elements in nitrogen microwave-plasma atomic emission spectrometry (MP AES) was studied. In the range of acid concentrations 0.1–0.5 M (for rare-earth elements, 0.1–0.9 M), the analytical signals of the elements did not change. The presence of a matrix element in a concentration of 1 wt % led to a significant change in the signal for most elements, which must be taken into account in selecting a calibration strategy. In MP AES, it is necessary to fully comply with the conformity of samples and calibration solutions regarding the type and concentration of acid and matrix elements.

Microwave plasma atomic emission spectrometry was used to determine 36 impurity elements in the zinc metal by a calibration method without adding the matrix element. The values of the...

In nitrogen microwave plasma atomic emission spectrometry, the intensities of analytical lines with low excitation energies increase in the presence of easily ionized elements. To compensate for this effect, we proposed to add additional matrix elements with ionization potentials below 6 eV (Rb, Ba, Sm, La, Eu, In, Al, and Ga) to sample solutions and calibration solutions in the determination of alkali and alkaline-earth metals. The concentration of an additional element, 75–100 mg/L, was selected based on the constancy of the analytical signals of analytes and the magnesium ratio Mg(II)/Mg(I). This concentration is insufficient for a significant change in temperature or electron density; that is, the added element is not a spectral buffer. The procedure was applied to the analysis of pore waters of bottom sediments of Lake Bolshoy Bagan (alkaline type of mineralization); the accuracy of the analysis was confirmed by the spiking method.