Use of peak area instrumental datum as possibility to improve the analytical sensitivity in the sequential voltammetric determination of ultra-trace iridium and lead in vehicle emission particulate matter

none1noThe possibility of using peak area instead of peak height is proposed for analytical sequential determination in particulate matter of iridium(III) and lead(II), elements linked to vehicle emissions.In the case of species present at ultratrace concentration level or having low reversibility degree of the electrodic processes, the employment of peak area, instead of peak current, permits to achieve limits of detection lower even more of one order of magnitude.The method is based on the voltammetric catalytic current of the Ir(III)-bromate and Pb(II)-bromate systems on glassy carbon (GC) electrode, using 0.25molL-1 acetate buffer pH4.3+7.7×10-2molL-1 NaBrO3+0.2molL-1 KCl [Pb(II)] and 0.25molL-1 acetate buffer pH4.3+7.7×10-2molL-1 NaBrO3+0.2molL-1 KCl+3.5×10-5molL-1 cetyltrimethylammonium bromide (CTAB) [Ir(III)] as the supporting electrolytes.For both elements, the accuracy, expressed as relative error e%, and the precision, expressed as relative standard deviation sr%, were satisfactory, being, generally, lower than 6%.To better validate the analytical procedure, a comparison with spectroscopic (electrothermal atomic absorption spectroscopy, ET-AAS) is also reportednoneC. LocatelliC. Locatell

Metals

Summary 1. Introduction 2. Analytical Procedure for the Metal Determination 2.1 Sampling 2.2 Sample Dissolution - Destruction of Organic Matter 2.2.1 Wet Ashing 2.2.2 Dry Ashing 2.2.3 Fusion 2.3 Separation and Concentration Methods 2.4 Laboratory Contamination 2.5 Instrumental Determination Methods 2.5.1 Electroanalytical Techniques 2.5.2 Spectrometric Methods 2.5.3 Other Techniques 3. Metals of Interest 3.1 Mercury 3.2 Patinum Group Metals (PGMs) 3.3 Miscellanea 4. Directives for Trace Metals in Food 5. Reference

Square wave catalytic adsorptive voltammetric determination of osmium, ruthenium and lead in vegetable environmental bio-monitors

The present work regards the simultaneous voltammetric determination of Os(VIII), Ru(III) and Pb(II) by square wave catalytic adsorptive voltammetry (SWCAdV) in vegetable environmental bio-monitor matrices. The analytical procedure was verified by the analysis of the standard reference materials: Olive Leaves BCR-CRM 062 and Tomato Leaves NIST-SRM 1573a. Precision and accuracy, expressed as relative standard deviation and relative error, respectively, were generally lower than 6% in all cases, whereas the limits of detection for all elements were lower than 5.0 \u3bcg kg-1. Once set up on the standard reference materials, the analytical procedure was transferred and applied to laurel leaves sampled in proximity to superhighway and in the Po river mouth area. A critical comparison with spectroscopic measurements is discussed

Voltammetric determination of metals as food contaminants: an excellent alternative to spectroscopic measurements. application to meals, vegetables, mussels, clams and fishes

The work regards the voltammetric determination of trace metals in different kinds of food matrices. First goal is relevant to the correct analytical procedure for the voltammetric determination of trace and ultra-trace metals - Platinum Group Metals (PGMs), Mercury (II), Copper (II), Lead (II), Cadmium (II) and Zinc (II) - in meals, vegetables, mussels, clams and fishes: this allows, evidently, to check high quality foodstuffs. The second goal is to show the advantages that the electrochemical approach may offer over atomic absorption spectroscopy. First, voltammetry, together with the standard addition method, is a valid analytical technique (good selectivity and, especially sensitivity) for the simultaneous element determination in complex matrices and it does not require enrichment steps, like solvent extraction, and/or particular sample treatments. Second, as regards precision, accuracy and limits of detection, the results obtained with the two techniques are both good and comparable in all cases, although voltammetry is better than atomic absorption spectroscopy, allowing simultaneous metal determinations in most cases. In fact, also Inductively Coupled Plasma (ICP) and Inductively Coupled Plasma - Mass Spectrometry (ICP-MS) permit multi-element determination, but the great advantage in using voltammetry is certainly the equipment-related costs: very low in the case of voltammetry, extremely high in the case of ICP and ICP-MS, in the latter case as much as 25-30 times higher. In this work Electrothermal Atomic Absorption Spectroscopy (ETAAS) was also chosen as comparison technique because of its well-established and tested robustness

Ultra-trace heavy metal determination in sea food by differential pulse catalytic voltammetry: application to fishes and bivalve molluscs

The paper proposes an analytical procedure regarding the voltammetric determination of chromium(VI), copper(II), lead(II), cadmium(II), zinc(II) and mercury(II) by differential pulse catalytic voltammetry (DPCV) in matrices involved in the food chain, but also employed as possible biological monitors for trace metal. The digestion of each matrix was carried out using a concentrated HCl-HNO3-H2SO4 acidic attack mixture. 0.23 mol L-1 dibasic ammonium tartrate buffer pH 4.9 + 5.9x10-2 mol L-1 NaBrO3 was employed as the supporting electrolyte. The voltammetric measurements were carried out using, as working electrodes, a stationary hanging mercury drop electrode (HMDE) [simultaneous determination of Cr(VI), Cu(II), Pb(II), Cd(II) and Zn(II)] and a gold electrode (GE) [determination of Hg(II)], a platinum electrode and Ag\u23aaAgCl\u23aaKClsat electrode as auxiliary and reference electrodes, respectively. The analytical procedure has been verified on the standard reference materials Mussel Tissue BCR-CRM 278 and Cod Muscle BCRCRM 422. For all the elements in the certified matrices, the precision as repeatability, expressed as relative standard deviation (sr) was lower than 6 %, while the trueness, expressed as relative error (e) was of the order of 5-6 %. Once set up on the standard reference materials, the analytical procedure was transferred and applied to fishes and molluscs sampled in the Po river mouth area

CRITICAL COMPARISON BETWEEN VOLTAMMETRIC AND SPECTROSCOPIC TECHNIQUES FOR THE DETERMINATION OF HEAVY METALS AND PLATINUM GROUP METALS (PGMS) CONCENTRATIONS IN ITALIAN AIRBORNE PARTICULATE MATTER

Recently, pollution linked to airborne particulate matter has drawn attention. The issue is due to a drastic increase of anthropic activities: industrial activities, in all their different typologies, and more and more increasing vehicular traffic. As a consequence, the totality of the pollutants associated with the various types of particulate are everywhere strictly dependent on the type of source of the same particulate. Moreover, the particle size evidently has a particular importance, since the decrease of the aerodynamic diameter of particulate corresponds to greater ease of penetration of the same particulate in the deeper levels of the respiratory system. This obviously is a serious problem for human and animal health, implying high costs in health care. Due to multiple simultaneous sources in areas at high anthropic impact, there are many pollutants associated with airborne particulate matter, both of inorganic and organic kind, and even simultaneously present on the same particulate samples. In any case, the pollutant determination in airborne particulate matter certainly must be accurate, reproducible and it must be especially characterized by very low limits of detection. In particular, the present work reports and discusses the different analytical procedures for the voltammetric and spectroscopic determination of heavy metals and metalloids (copper, lead, cadmium, zinc, mercury, tellurium, arsenic, selenium, tin, antimony, vanadium, nickel, chromium) in airborne particulate matter sampled in two sites, differently influenced by anthropic pollution. An additional sampling, carried out in a zone at very low anthropic impact, was chosen for eventual comparisons. The chosen particulate-matter size was PM2.5 (aerodynamic diameter < 2.5 \ub5m) even if the proposed methodologies evidently can be also applied to all other particle sizes of interest. A separate section will be dedicated to the analytical procedure for the determination in airborne particulate matter of new emerging anthropic polluting traffic-related pollutants, i.e. the platinum group metals (PGMs) \u2014 platinum, palladium, rhodium, osmium, ruthenium and iridium \u2014 that, in the last decade, have aroused much interest from scientific community

Trace level voltammetric determination of heavy metals and total mercury in tea matrices (Camellia sinensis)

An analytical procedure regarding the voltammetric determination of mercury(II), copper(II), lead(II), cadmium(II) and zinc(II) by square wave anodic stripping voltammetry (SWASV) in matrices involved in food chain is proposed. In particular, tea leaves were analyzed as real samples. The digestion of each matrix was carried out using a concentrated HCl-HNO3-H2SO4 acidic attack mixture; 0.01molL-1 EDTA-Na2+0.15molL-1 NaCl+0.5molL-1 HCl was employed as the supporting electrolyte. The voltammetric measurements were carried out using a conventional three electrode cell, employing, as working electrodes, a gold electrode (GE) and a stationary hanging mercury drop electrode (HMDE). The analytical procedure has been verified on the standard reference materials Spinach Leaves NIST-SRM 1570a, Tomato Leaves NIST-SRM 1573a and Apple Leaves NIST-SRM 1515. For all the elements, the precision as repeatability, expressed as relative standard deviation (sr) was of the order of 3-5%, while the trueness, expressed as relative error (e) was of the order of 3-7%. Once set up on the standard reference materials, the analytical procedure was applied to commercial tea leaves samples.A critical comparison with spectroscopic measurements is also discussed

Toxic metals in herbal medicines. A review.

The present review proposes an exhaustive focus on what are the metals of interest, and what is the state of the art about analytical methodologies suitable to detect these toxic metals in herbal medicines. This review would also be a stimulus to solicit International Organizations to fill the gap of the lack of strict and comprehensive laws regulating the maximum allowable concentrations for an increasing number of contaminants in these matrices, especially considering their enormous consumption. Herbal medicines are more and more worldwide used. This fact certainly presents serious problems for the potential human health risks. This is due to the fact that the laws in force generally do not provide for strict quality controls of herbal medicines to certify the concentration of compounds and elements that may be hazardous for human health, and sometimes very severe or even lethal. Heavy metals have a decidedly substantial part of the contaminants in herbal medicines