Determination of vanadium(V) in the particulate matter of emissions and working areas by sequential dissolution and solid-phase extraction.

A method based on selective sequential dissolutions is proposed to determine total vanadium(V) in particulate matter of emissions and working areas at concentrations 1,000 times lower than the threshold limit of 0.05 mg m(-3). Separation and preconcentration of vanadium(V) has been achieved by solid-phase extraction on Chelex 100 resin. Possible influence of the matrix has been investigated for two standard reference materials (SRMs), NIST SRM 1648 and BCR-038, before and after spiking, with vanadium(V) recovery in the range 97-103%.

Characterization of an enzyme linked immunosorbent assay for Aflatoxin B(1) based on commercial reagents.

Two indirect ELISA have been investigated for the determination of Aflatoxin B(1), employing only reagents commercially available, whose composition is not exactly known. In both cases the antigen (Aflatoxin B(1)-BSA) was coated to the solid phase (polystyrene microtiter plates). In one procedure the specific antibody was a conjugate with peroxidase, while in the other one it was not conjugated, and a second antibody labelled with alkaline phosphatase was used. A simple model was employed to characterize the equilibria, which is of help also if the exact composition of the immunoreagents is not known, and allows to predict the shape and position of the competition curve. The factors which determine the dynamic range were found to be the affinity constant the complex in the solid and the amount of antigen in the solid, and the affinity constant of the complex in solution phase. Useful aspects of the antigen-antibody complexation equilibria in the solid phase were investigated by ELISA at zero concentration of antigen in solution, obtaining c (s)c ( *) and K'f(n)(T). The equilibria in solution were studied by competition ELISA, obtaining K, the affinity constant of the antigen-antibody complex in solution. Similar results were obtained with the two procedures, for instance the affinity constant in solution was 2 x 10(8). A procedure for the determination of Aflatoxin B(1) in food samples was developed.

Sequential extraction procedure for speciation of inorganic cadmium in emissions and working areas.

A sequential extraction procedure for separating and concentrating soluble Cd(II) salts, CdO, Cd(0), CdS, CdSe and cadmium-aluminosilicates, has been developed for the cadmium speciation in samples such as particulate matter in emissions and working areas. The proposed procedure has been tested first on synthetic samples prepared in a laboratory with the different cadmium salts, then also in the presence of atmospherical particulate matter sampled in a laboratory of the Department of Analytical Chemistry, previously checked for the absence of cadmium. Finally the speciation was tested on particulate matter collected near the emission of a power plant fed by coal, after emission's treatment by electrostatic precipitator: matrix spiking and recovery analyses have been evaluated and the repeatability of the cadmium speciation was assessed by performing multiple analyses of the spiked samples. Quantitative determinations have been made by FAAS and GFAAS through the standard additions method.

Determination of inorganic beryllium species in the particulate matter of emissions and working areas.

A sequential extraction procedure for separating and determining Be(0), soluble Be(II) inorganic compounds, BeO and beryllium silicates in samples such as particulate matter of emissions and working areas, has been developed. The proposed procedure has been tested on synthetic samples prepared with the inorganic beryllium compounds, in the presence of atmospherical particulate matter sampled in a laboratory of the Department, previously checked for the absence of beryllium. The speciation was then repeated on a sample of fly ash deriving from a solid waste incinerator and on a reference material (Coal Fly ash SRM 1633a, by NIST), followed by an evaluation of matrix spiking and recovery analyses. Performing multiple analyses of the spiked samples assessed the repeatability of the procedure. Quantitative determinations have been made by inductively coupled plasma optical emission spectrometry (ICP-OES) and electrothermal atomic absorption spectrometry (ETAAS). The possible interferences of the most common ions have been investigated. The selective sequential extractions allow one to separate and to determine different inorganic beryllium species, to which a different toxicity and therefore, a different risk are related: it is the case for example of metallic beryllium and beryllium oxide.

Determination of inorganic nickel compounds in the particulate matter of emissions and workplace air by selective sequential dissolutions.

A speciation method of inorganic nickel compounds in airborne particulate, based on selective sequential extractions, is described. It allows the separation and the determination of Ni(0), Ni(II) soluble salts such as sulphate and chloride, Ni insoluble compounds such as nickel oxide and sulphide, to which a different toxicity and therefore a different risk are related. The nickel concentration in each fraction was determined by Flame or Furnace Atomic Absorption Spectroscopy. The proposed procedure has been tested first, on synthetic samples prepared with the different nickel compounds, in the presence of atmospherical particulate matter not containing nickel, in order to take into account the possible matrix influence. The speciation was then repeated on four different samples (fly ash deriving from a solid waste incinerator and three RSMS from NIST: Coal Fly ash SRM 1633b, Urban Particulate 1648, Washington Dust 1649), followed by an evaluation of matrix spiking and recovery analyses. Performing multiple analyses of the spiked samples assessed the repeatability of the procedure.

Sequential extraction procedure for speciation of inorganic selenium in emissions and working areas.

A sequential extraction procedure for separating inorganic species of selenium in particulate matter of emissions and working areas, has been developed. The proposed procedure has been tested first on synthetic samples prepared in laboratory with the different selenium salts, then in the presence of atmospherical particulate matter sampled in a laboratory of the department of general chemistry, previously checked for the absence of selenium. Finally the speciation was tested on a reference material (urban particulate matter NIST SRM 1648), certified for the total selenium content. The sample was first treated with the proposed procedure, followed by an evaluation of matrix spiking and recovery analyses. The repeatability of the selenium speciation was assessed by performing multiple analyses of the spiked samples. Quantitative determinations have been made by AAS and voltammetry. The possible interferences of the most common ions have been investigated.