Spectral and non-spectral interferences observed in the determination of selenium by ICP-AES were investigated in this study. The identity of the carbon-induced emission peak that interferes on the Se 196.090 nm analytical line was clarified. It was found that this peak was not a part of a CN band but most likely belongs to a spectral band emitted by the CO molecule. Non-spectral interferences of matrix elements C, S, P and Br assisting in the enhancement of selenium emission were found. Concentration dependences of these matrix effects were measured in the range of 0.5–20 g L−1 of the matrix element and 0.1–100 mg L−1 of Se. No enhancement of the Mg I 285.213 nm line was observed when the influence of these matrix elements on magnesium was monitored for comparison at the same time. The enhancement of selenium emission was about 50% in the most significant case (sulfur, 10 g L−1). A similar effect was observed when gaseous compounds of C and S were introduced into the ICP. The mechanism of this matrix effect was studied and partially clarified as being probably related to ionization of matrix elements.
Ethanol dehydration is effectively catalyzed by solid acids, such as HZSM-5, alumina, or silica–alumina. In these catalysts, the amount, nature, and strength of acid sites is believed to determine catalyst activity and stability. However, surface hydrophilicity or hydrophobicity can be suggested as another decisive materials property that can directly influence performance. For example, a more hydrophobic surface might be beneficial in repelling the co-product of the reaction, water. However, these aspects have been studied only scarcely in the context of alcohol dehydration. Here, a series of mesoporous hybrid aluminosilicate materials containing CH3Si groups was prepared in one pot by non-hydrolytic sol–gel (NHSG). The presence of the methyl groups was verified by IR, solid-state NMR, and ToF-SIMS. Aluminum is mostly incorporated in tetrahedral coordination in the hybrid silica matrix. Two parameters were varied: (i) the aluminum loading (Si : Al ratio) and (ii) the degree of methylation (Si : MeSi ratio). On the one hand, changing the Si : Al ratio had a marked and expected impact on acidity. On the other hand, unexpectedly, the introduction of methyl groups had no clear influence on sample hydrophobicity. Nevertheless, some of the methylated aluminosilicate catalysts markedly outperformed the purely inorganic catalysts and a commercial silica–alumina benchmark. While a direct influence of surface hydrophilicity or hydrophobicity is unlikely, characterization of acidity (IR-pyridine) revealed that the improved performance for hybrid catalysts is correlated with a modification of the acidic properties (higher proportion of Lewis acid sites) caused by the introduction of methyl groups during the sol–gel process. A decisive role of acidity in ethanol dehydration was confirmed by an experiment with delayed addition of the Al precursor in the NHSG synthesis of the hybrid aluminosilicate. This led to a higher Al surface concentration, marked acid sites number increase, and better catalytic performance, even competing with the state of the art HZSM-5 in terms of ethylene yield.
10 March 2022 in Journal of Analytical Atomic Spectrometry
In the past couple of years, laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) has been widely used for trace element analysis in solid samples and the study of their distribution.
30 July 2004 in Analytical and Bioanalytical Chemistry
The inhalation of metal (including lead) nanoparticles poses a real health issue to people and animals living in polluted and/or industrial areas. In this study, we exposed mice to lead(II) nitrate nanoparticles [Pb(NO3)2 NPs], which represent a highly soluble form of lead, by inhalation. We aimed to uncover the effects of their exposure on individual target organs and to reveal potential variability in the lead clearance. We examined (i) lead biodistribution in target organs using laser ablation and inductively coupled plasma mass spectrometry (LA-ICP-MS) and atomic absorption spectrometry (AAS), (ii) lead effect on histopathological changes and immune cells response in secondary target organs and (iii) the clearance ability of target organs. In the lungs and liver, Pb(NO3)2 NP inhalation induced serious structural changes and their damage was present even after a 5-week clearance period despite the lead having been almost completely eliminated from the tissues. The numbers of macrophages significantly decreased after 11-week Pb(NO3)2 NP inhalation; conversely, abundance of alpha-smooth muscle actin (α-SMA)-positive cells, which are responsible for augmented collagen production, increased in both tissues. Moreover, the expression of nuclear factor κB (NF-κB) and selected cytokines, such as tumor necrosis factor alpha (TNFα), transforming growth factor beta 1 (TGFβ1), interleukin 6(IL-6), IL-1α and IL-1β , displayed a tissue-specific response to lead exposure. In summary, diminished inflammatory response in tissues after Pb(NO3)2 NPs inhalation was associated with prolonged negative effect of lead on tissues, as demonstrated by sustained pathological changes in target organs, even after long clearance period.