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This work explores chelating capabilities of 1-butyl-2-diphenylphosphino-3-methylimidazolium hexafluorophosphate (BDPPIMPF 6) as a task-specific ionic liquid (TSIL) for metal extraction/preconcentration procedures. To this end, metal extraction by BDPPIMPF 6 for 21 elements (Ag, Al, As, Au, Co, Cr, Cu, Fe, Ir, Mn, Ni, Pb, Pd, Pt, Re, Rh, Ru, Sc, Ti, V, and Zn) were evaluated. This TSIL specifically forms chelating complexes with several elements of Group 10 (Pd and Pt) and Group 11 (Ag and Cu) of the Periodic Table. Chelating capabilities of BDPPIMPF 6 has been exploited for developing a novel methodology for the simultaneous determination of Ag, Cu, Pd, and Pt by means of dispersive liquid-liquid microextraction and inductively coupled plasma optical emission spectrometry detection (DLLME-ICP-OES). This methodology afforded enrichment factors of 14 to 70 and limits of detection (LoD) of 0.2–2 μg L−1 for Ag, Cu, Pd and Pt. These LoD values were between 110 and 35-fold lower than those obtained by direct analyses with ICP-OES (i.e., no DLLME treatment). Finally, the proposed method has been applied to the analysis of Ag, Cu, Pd, and Pt in water and pharmaceutical products. Irrespective of matrix characteristics, quantitative recoveries were found for all the elements investigated thus highlighting methodology robustness. [Display omitted] • BDPPIMPF 6 shows a great affinity for Pd and Pt (Group 10) and Ag and Cu (Group 11). • Extraction of the different elements is mainly controlled by solution pH. • A new TSIL-DLLME-based methodology has been developed with ICP-OES detection. • TSIL has been successfully applied in the analysis of water and drug samples. [ABSTRACT FROM AUTHOR]

In this work, the influence of carbon-, sulfur-, and phosphorus-based charge transfer reactions on the emission signal of 34 elements (Ag, Al, As, Au, B, Ba, Be, Ca, Cd, Co, Cr, Cu, Fe, Ga, Hg, I, In, Ir, K, Li, Mg, Mn, Na, Ni, P, Pb, Pd, Pt, S, Sb, Se, Sr, Te, and Zn) in axially viewed inductively coupled plasma–atomic emission spectrometry has been investigated. To this end, atomic and ionic emission signals for diluted glycerol, sulfuric acid, and phosphoric acid solutions were registered and results were compared to those obtained for a 1% w w − 1 nitric acid solution. Experimental results show that the emission intensities of As, Se, and Te atomic lines are enhanced by charge transfer from carbon, sulfur, and phosphorus ions. Iodine and P atomic emission is enhanced by carbon- and sulfur-based charge transfer whereas the Hg atomic emission signal is enhanced only by carbon. Though signal enhancement due to charge transfer reactions is also expected for ionic emission lines of the above-mentioned elements, no experimental evidence has been found with the exception of Hg ionic lines operating carbon solutions. The effect of carbon, sulfur, and phosphorus charge transfer reactions on atomic emission depends on (i) wavelength characteristics. In general, signal enhancement is more pronounced for electronic transitions involving the highest upper energy levels; (ii) plasma experimental conditions. The use of robust conditions (i.e. high r.f. power and lower nebulizer gas flow rates) improves carbon, sulfur, and phosphorus ionization in the plasma and, hence, signal enhancement; and (iii) the presence of other concomitants (e.g. K or Ca). Easily ionizable elements reduce ionization in the plasma and consequently reduce signal enhancement due to charge transfer reactions. [ABSTRACT FROM AUTHOR]

Results of a systematic study concerning non-spectral interferences from sulfuric acid containing matrices on a large number of elements in inductively coupled plasma–mass spectrometry (ICP-MS) are presented in this work. The signals obtained with sulfuric acid solutions of different concentrations (up to 5% w w − 1 ) have been compared with the corresponding signals for a 1% w w − 1− nitric acid solution at different experimental conditions (i.e., sample uptake rates, nebulizer gas flows and r.f. powers). The signals observed for 128 Te + , 78 Se + and 75 As + were significantly higher when using sulfuric acid matrices (up to 2.2-fold for 128 Te + and 78 Se + and 1.8-fold for 75 As + in the presence of 5 w w -1 sulfuric acid) for the whole range of experimental conditions tested. This is in agreement with previously reported observations. The signal for 31 P + is also higher (1.1-fold) in the presence of sulfuric acid. The signal enhancements for 128 Te + , 78 Se + , 75 As + and 31 P + are explained in relation to an increase in the analyte ion population as a result of charge transfer reactions involving S + species in the plasma. Theoretical data suggest that Os, Sb, Pt, Ir, Zn and Hg could also be involved in sulfur-based charge transfer reactions, but no experimental evidence has been found. The presence of sulfuric acid gives rise to lower ion signals (about 10–20% lower) for the other nuclides tested, thus indicating the negative matrix effect caused by changes in the amount of analyte loading of the plasma. The elemental composition of a certified low-density polyethylene sample (ERM-EC681K) was determined by ICP-MS after two different sample digestion procedures, one of them including sulfuric acid. Element concentrations were in agreement with the certified values, irrespective of the acids used for the digestion. These results demonstrate that the use of matrix-matched standards allows the accurate determination of the tested elements in a sulfuric acid matrix. [ABSTRACT FROM AUTHOR]

Abstract: A systematic study on the influence of carbon on the signal of a large number of hard-to-ionize elements (i.e. B, Be, P, S, Zn, As, Se, Pd, Cd, Sb, I, Te, Os, Ir, Pt, Au, and Hg) in inductively coupled plasma–mass spectrometry has been carried out. To this end, carbon matrix effects have been evaluated considering different plasma parameters (i.e. nebulizer gas flow rate, r.f. power and sample uptake rate), sample introduction systems, concentration and type of carbon matrix (i.e. glycerol, citric acid, potassium citrate and ammonium carbonate) and type of mass spectrometer (i.e. quadrupole filter vs. double-focusing sector field mass spectrometer). Experimental results show that P, As, Se, Sb, Te, I, Au and Hg sensitivities are always higher for carbon-containing solutions than those obtained without carbon. The other hard-to-ionize elements (Be, B, S, Zn, Pd, Cd, Os, Ir and Pt) show no matrix effect, signal enhancement or signal suppression depending on the experimental conditions selected. The matrix effects caused by the presence of carbon are explained by changes in the plasma characteristics and the corresponding changes in ion distribution in the plasma (as reflected in the signal behavior plot, i.e. the signal intensity as a function of the nebulizer gas flow rate). However, the matrix effects for P, As, Se, Sb, Te, I, Au and Hg are also related to an increase in analyte ion population caused as a result of charge transfer reactions involving carbon-containing charged species in the plasma. The predominant specie is C+, but other species such as CO+, CO2 +, C2 + and ArC+ could also play a role. Theoretical data suggest that B, Be, S, Pd, Cd, Os, Ir and Pt could also be involved in carbon based charge transfer reactions, but no experimental evidence substantiating this view has been found. [Copyright &y& Elsevier]

Abstract: The influence of the sample introduction system on the signals obtained with different tin compounds in inductively coupled plasma (ICP) based techniques, i.e., ICP atomic emission spectrometry (ICP–AES) and ICP mass spectrometry (ICP–MS) has been studied. Signals for test solutions prepared from four different tin compounds (i.e., tin tetrachloride, monobutyltin, dibutyltin and di-tert-butyltin) in different solvents (methanol 0.8% (w/w), i-propanol 0.8% (w/w) and various acid matrices) have been measured by ICP–AES and ICP–MS. The results demonstrate a noticeable influence of the volatility of the tin compounds on their signals measured with both techniques. Thus, in agreement with the compound volatility, the highest signals are obtained for tin tetrachloride followed by di-tert-butyltin/monobutyltin and dibutyltin. The sample introduction system exerts an important effect on the amount of solution loading the plasma and, hence, on the relative signals afforded by the tin compounds in ICP–based techniques. Thus, when working with a pneumatic concentric nebulizer, the use of spray chambers affording high solvent transport efficiency to the plasma (such as cyclonic and single pass) or high spray chamber temperatures is recommended to minimize the influence of the tin chemical compound. Nevertheless, even when using the conventional pneumatic nebulizer coupled to the best spray chamber design (i.e., a single pass spray chamber), signals obtained for di-tert-butyltin/monobutyltin and dibutyltin are still around 10% and 30% lower than the corresponding signal for tin tetrachloride, respectively. When operating with a pneumatic microconcentric nebulizer coupled to a 50°C-thermostated cinnabar spray chamber, all studied organotin compounds provided similar emission signals although about 60% lower than those obtained for tin tetrachloride. The use of an ultrasonic nebulizer coupled to a desolvation device provides the largest differences in the emission signals, among all tested systems. [Copyright &y& Elsevier]

In inductively coupled plasma optical emission spectrometry (ICP-OES), the presence of carbon in the matrix strongly affects (positively and negatively) the emission signal of atomic lines. However, the emission signal of ionic lines is mostly unaffected by this concomitant. The goal of this work is to gain insight into the origin of carbon matrix effects on the signal of atomic lines in ICP-OES. To this end, the emission signal of a total of 3608 lines (i.e., 1755 atomic and 1853 ionic lines) of 62 elements (Ag, Al, As, Au, B, Ba, Be, Ca, Cd, Ce, Co, Cr, Cs, Cu, Dy, Er, Eu, Fe, Ga, Gd, Ge, Hg, Ho, I, In, Ir, K, La, Li, Lu, Mg, Mn, Mo, Na, Nb, Nd, Ni, P, Pb, Pd, Pr, Pt, Re, Rh, S, Sb, Sc, Se, Sm, Sn, Sr, Tb, Te, Th, Ti, Tm, U, V, Y, Yb, Zn and Zr) were registered for carbon containing solutions (20 g L−1) prepared from glycerol. Results were compared to those obtained operating a 1% w w−1 HNO 3 solution. Compared to the HNO 3 reference solution, emission signals for As, B, Hg, I, P, Se and Te atomic lines were increased for the carbon containing solution. However, signal suppression was noticed for the signal emission of Ag, Al, Ba, Be, Ca, Cd, Co, Cr, Cs, Eu, Fe, Ga, Ge, K, Ho, In, La, Li, Lu, Mg, Mn, Mo, Na, Nb, Ni, Pb, Pd, Pr, Pt, Re, Rh, S, Sb, Sc, Sn, Sr, Ti, Tm, V, Y and Zr atomic lines. No measurable matrix effects within experimental uncertainties were registered for Au, Cu, Ir, Gd and Zn atomic lines. As regards Ce, Dy, Er, Nd, Sm, Tb, Th, U and Yb no clear conclusion about matrix effects was feasible due to the limited atomic emission wavelengths monitored. Experimental results showed that the intensity of matrix effects depends on both analyte ionization energy and the energy of the electronic upper level involved in the electronic transition. Matrix effects on atomic emission lines can be explained by the simultaneous occurrence of different mechanisms: (i) charge transfer reactions; (ii) collisional ionization; and (iii) collisional excitation with carbon-based species. Because these mechanisms mostly affect analyte atomic population, carbon matrix effects are more significant on the emission signal of atomic lines rather than ionic ones. Finally, the judicious analyte wavelength selection is critical to minimize carbon matrix effects for those elements for which the most sensitive wavelength is atomic (i.e., Se and alkali elements). On this regard, the selection of the internal standard should consider both the ionization energy and the energy of the electronic upper level of the analyte. Unlabelled Image • The emission of atomic lines in ICP-OES is strongly affected by carbon. • Carbon matrix effects depend on E ion and E upper level. • Different carbon-based mechanisms affect the emission of atomic lines. [ABSTRACT FROM AUTHOR]