No abstract

Iron nanoparticles were produced using the extract of mortiño berry (Vaccinium floribundum) (vZVI) as reducing and stabilizer agent. Fresh nanoparticles were characterized using TEM, XRD, and FTIR techniques, while laboratory experiments were conducted to assess the removal of total petroleum hydrocarbons (TPHs) from water and soil after treatment with synthesized nanoscale iron particles. Nanoparticles as produced were spherical in the range of 5–10 nm. After treatment with vZVI nanoparticles, water contaminated with two concentrations of TPHs (9.32 mg/L and 94.20 mg/L) showed removals of 85.94% and 88.34%, respectively, whereas a contaminated soil with a TPHs concentration of 5000 mg/kg treated during 32 h with nanoparticles reached a removal of 81.90%. Results indicate that the addition of vZVI nanoparticles produced strong reducing conditions, which accelerate removal of TPHs and suggest that these nanoparticles might be a promising technology to clean up TPHs contaminated water and soils.

No abstract

Digestion programmes for different types of samples (milk, sausage and lyophilized pig kidney certified reference material) have been developed using a focused microwave digestor prior to the determination of selenium. The digestion step does not alter the oxidation state of the analyte; thus, the speciation of the target analyte is also achieved with the help of the microwave digestor, which facilitates a subsequent on-line reduction step in a flow injection (F'I) manifold before determination by FI cathodic stripping voltammetry. Excellent recoveries for the spiked and certified values were obtained using digestion programmes which varied from 2 0 4 5 min. The on-line microwave procedure for the reduction of Sew affords good sensitivity and linearity (S120 yg 1-1, r = 0.994) of the over-all determination method, and dramatically reduces the time necessary for Sen reduction.

Two methods based on flow injection atomic fluorescence have been developed in order to speciate Se as Se'"-SeV'. Both methods use hydride generation of Sew with atomic fluorescence detection as the derivatization-detection step. In the first method, two sample plugs are injected simultaneously in series, so that the first plug passes straight to the detector to determine Se'". The second plug passes through a focused microwave device where Se"' is reduced to Sew prior to its conversion into the hydride. The Se"' content is then given as the difference between the two results. In the second method a mini-column is used to retain both the Se species; Sew and Sen are then eluted sequentially with formic and hydrochloric acids, respectively. The columns can be used for preconcentration of the analytes as well as for sampling. Both methods show exceptional sensitivity [limits of detection (3s) of 0.04 pg 1-'1 and wide linear range up to 50 pg I-', with excellent linearity (9 = 0.999), and reproducibility (relative standard deviation<5%). The methods have been used in an intercomparison exercise for the Measurements and Testing Programme and have been applied to the determination of the analytes in tap water and haemodialysis samples.