Voltammetric Peak Area as Instrumental Datum. A Possibility to Improve the Determination at Ultratrace Level Concentration of Platinum Group Metals (PGMs) and Lead. Application to Particulate Matter

Abstract

Peak area as instrumental datum for determining the concentration of metals in solution instead of peak height is proposed for analytical voltammetric determinations. In the case of species present at ultratrace concentration level or having low reversibility degree of the electrodic processes, the employment of peak area permits to achieve limits of detection lower even more of one order of magnitude. The present work shows the possibility of determining at ultratrace level concentration Pd(II), Pt(II), Rh(III) and Pb(II) by voltammetry in particulate matter; these species, linked to vehicle emissions, show to have, in the supporting electrolytes employed, a very high irreversibility degree of the electrodic processes. 0.1 mol/L HCl, 0.1 mol/L HCl þ 1.8 Â 10 À4 mol/L dimethylglyoxime (DMG) and 0.6 mmol/L formaldehyde þ 1.2 mmol/L hydrazine (formazone complex) in 0.1 mol/L HCl were employed as the supporting electrolytes. For all the elements, the accuracy, expressed as relative error e%, and the precision as repeatability, expressed as relative standard deviation s r (%), were very satisfactory, being lower than 6%. To better validate the analytical procedure, a comparison with spectroscopic (graphite furnace atomic absorption spectroscopy, GFAAS) measurements is also reported.

Improvement of the ultra-trace voltammetric determination of Rh in environmental samples using signal transformation

“…Several previous works applied and improved different techniques for Rh determination, including atomic absorption spectrometry [9,10] or neutron activation analysis [11,12]; however, inductive coupled plasma mass spectrometry ICP-MS [13][14][15][16][17] and adsorptive voltammetry [18][19][20][21][22][23][24][25][26] became the most widely used method due to their higher sensitivity. Besides, some other studies solved important issues (e.g.…”

Redox behavior and adsorptive cathodic stripping voltammetric determination of nanomolar levels of palladium using a novel Schiff base reagent containing a squaric acid moiety

“…The analytical features (LOD, LOQ and linear dynamic range) of the developed method compare favorably with those of many spectrometric [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][39][40][41][42][43][44][45] and electroanalytical methods. [19][20][21][22][23][24][25][26][27][28][29]46,47 The developed method provides better LOD and LDR, ease of use and less interference (Table 2). Some of these other methods have shown high LOD and serious interference by halide ions.…”

“…Numerous adsorptive cathodic stripping voltammetry (AdCSV) methods have been reported for sensitive Pd concentration determination. [19][20][21][22][23][24][25][26][27][28][29] To the best of our knowledge, the Schiff base 3,4-bis(2-hydroxyphenylimino)cyclobut-1-en-1,2-diol (SQ-OH) (Fig. 1) has so far not been used as a chelating agent for voltammetric and/or spectrometric determination of Pd and other platinum-group elements.…”

Anodic Stripping Tin Titration: A Method for the Voltammetric Determination of Platinum at Trace Levels

“…Voltammetric methods play a major role in PGM determination, as they can reach extreme sensitivities (see ref and references therein): limits of detections (LOD) below 0.1 μg/L are reported for adsorptive stripping voltammetry (AdSV), whereas catalytic adsorptive stripping voltammetry (CAdSV) techniques show LOD ranging from 0.03 to 70 ng/L. − …”

“…3−5 From an analytical chemist's point of view, these are probably the reasons why we assisted in the development of various methods for the determination of platinum on different samples in the last two decades: depending on the matrix and on the concentration level to be determined, several spectrometric techniques such as XRF, AAS, ICP-OES, and ICP-MS may be successfully used to investigate samples like exhausted catalysts, road dust, particulate matter, vegetation, soil, water, and biological materials. 6−10 Voltammetric methods play a major role in PGM determination, as they can reach extreme sensitivities (see ref 11 and references therein): limits of detections (LOD) below 0.1 μg/L are reported for adsorptive stripping voltammetry (AdSV), 12 whereas catalytic adsorptive stripping voltammetry (CAdSV) techniques show LOD ranging from 0.03 to 70 ng/ L. 13−15 Nevertheless, these extremely low LOD values (close to the ones achievable with sector field ICP-MS) are partially counterbalanced by limited linear ranges, as known from the literature 11 and directly experienced by some of us. 16 Therefore, these voltammetric techniques (which are surely suitable to study environmental samples) reveal some limitations in the field of catalysts characterization.…”