Characterization of aluminum species with nitrate, perchlorate and sulfate ions in the positive and negative ion mode by electrospray ionization mass spectrometry

Abstract

The application of electrospray ionization mass spectrometry (ESI-MS) for aluminum speciation in the positive and negative ion modes was discussed. Aluminum nitrate, perchlorate and sulfate solutions were measured by ESI-MS. In the positive ion mode, aluminum species containing anions (Al-L; L=NO3, ClO4 and SO4) were identified, while [Al(OH)2(H2O)n]+ (n=2-4) were the main species. The affinity of the anions with Al3+ estimated by ESI-MS was consistent with the hardness of the anions (hard and soft acids and bases principle) and the results from 27Al nuclear magnetic resonance studies. This indicates that the results observed from the positive ion mode preserved the chemical state of aluminum in the solution. In the negative ion mode, [Al(OH)4-nLn]- (n=0-2, L=NO3, ClO4) were the main species, which were considered to be converted from positive aluminum species, [Al(OH)(H2O)n]+ (n=2-4), by the successive addition of anions. Anions did not only attach to one aluminum ion but also bridged two aluminum ions. In Al2(SO4)3 solution, the behavior of SO4(2-) in the negative ion mode differed from that of NO3- and ClO4-. This may reflect the affinity of SO4(2-) with Al3+ in the solution or in the mass spectrometer or in both. Finally, detection mechanisms for the aluminum species in the solution are proposed for both the positive and negative ion modes. It is shown that ESI-MS can be used to observe the interaction between Al3+ and anions. We show the importance of the interpretation of the results by ESI-MS for obtaining new information of the metal species in the solution.

Electrospray mass spectrometry studies of purified aluminum tridecamer in 50:50 water/methanol mixture

“…Conversely, the presence of strong ligands such as ethylenediamine tetraacetic acid (EDTA) can rapidly convert all aluminum species into stable complex, thereby leading to no useful kinetic data (Kebarle and Tang, 1993;Urabe et al, 2009). The present work revealed that methanol has an intermediate affinity to Al cluster to lead to incremental replacement of water ligand, so a complete addition/substitution reaction networks as shown in Fig.…”

“…The electrospray ionization mass spectrometry (ESI-MS) was applied to identify aluminum speciation in aqueous solution (Sarpola et al, 2004;Urabe et al, 2008Urabe et al, , 2009Zhao et al, 2009). The aluminum tridecamer (Al 13 )-containing polyaluminum chloride (PACl) is widely utilized for coagulation of natural colloids in water treatment industries (Ji et al, 2009;Lin et al, 2009;Wang et al, 2004;Xu et al, 2003;Zhang et al, 2009).…”

Electrospray Ionization Time-of-Flight Mass Spectrum Analysis Method of Polyaluminum Chloride Flocculants

“…The calculated result included all of the Al species identified with spectrum analysis principles from previous studies 2, 16,17,19 (denoted with gray background), as well as some others. Those additional species often have relative lower intensity peaks, as shown in the mass spectrum in Figure 1, but could be identified nevertheless.…”

Clustering of palladium(II) chloride in acetonitrile solution investigated by electrospray mass spectrometry

“…Recently has even been argued that ESI not at all samples the bulk solution, but only the droplet surfaces instead [67]. While this situation certainly demands for additional investigations on the electrospray process itself, several obvious correlations between ESI data and solution properties being observed in recent years [17,[27][28][29][68][69][70][71][72] request for an intermediate, deliberately more pragmatic approach. To this end, we have recently proposed a merely phenomenological method via modeling of the concentration dependences according to which it is suggested that for the aggregation of simple metal salts in aqueous solution, the effective concentration in the spray process (c spray ) can exceed the concentration of the feed solutions (c feed ) by several orders of magnitude [29] and the correlation appears to hold true also for solutions in acetonitrile [27].…”