Speciation analysis of thallium in water samples after separation/ preconcentration with the EmporeTM chelating disk

A simple, reliable and novel solid phase extraction procedure using the Empore chelating disk has been developed for determination of Tl(I) and Tl(III) in environmental water samples by electrothermal atomic absorption spectrometry (ETAAS). The influence of humic acids on separation/preconcentration of thallium species with the Empore chelating disk is investigated. The preconcentration factor and detection limit are 500 and 5 ng L-1, respectively. The recoveries are in the range 93-103% for mineral, pond, sea, snowmelt, waste waters at 28-500 ng L-1 Tl and in the range 82-112% for river waters at 18-28 ng L-1 Tl

Field sampling, speciation and determination of dissolved iron (II) and iron (III) in waters

A simple and rapid field sampling procedure was developed for the speciation of dissolved Fe(II) and Fe(III) in waters. The determination of iron species was possible by selective batch solid phase extraction of Fe(III) using chelating resin Chelex-100 in H+ form, sample acidity range of pH 1.5-2.5, elution with 0.03 mol L-1 NH4-EDTA, and detection of Fe(III) by flame or electrothermal atomic absorption spectrometry (ETAAS). The concentration of Fe(II) was determined in the solution above the resin by direct ETAAS or after adsorption on Chelex-100 in NH4+ form without the need for preoxidation of Fe(II) to Fe(III). Water samples were collected in situ and filtered by passing them through a syringe filter (0.45 mu m). The batch procedure was performed at the field and then, the tubes containing the resins with the loaded analytes were returned to the laboratory where the iron species were eluted and determined. Field sampling prevents changes in the oxidation state of iron. The effect of humic acid was also investigated. The results obtained indicated that the method was not affected by the presence of up to 0.01% humic acid. The limit of detection (3s) was 0.8 mu g L-1 Fe (ETAAS detection). The relative standard deviation (n=10) ranged from 2% at the 1 mg L-1 Fe up to 20% at the 1 mu g L-1 Fe(III) level. Recoveries of spiked Fe(II) and Fe(III) in river, lake, tap and groundwater samples ranged from 93 to 105%

Sterically stabilized liposomes as a platform for salinomycin metal coordination compounds

Sterically stabilized DPPC:CHOL:DSPE-PEG-2000 liposomal formulations of the lipophilic complexes of salinomycin with Na(I), K(I), Mn(II), Co(II), and Ni(II) ions were prepared by film-hydration method at different drug-to-DPPC molar ratios. For the K(I) and Na(I) complexes, optimal loading was established at a drug-to-DPPC molar ratio of 0.5:1, whereas for the Me(II) complexes, it was encountered at 0.1:1. DLS revealed uniform LUV populations (130-160 nm) with monomodal size distribution, further corroborated by AFM. Free and entrapped salinomycinates exhibited cytotoxicity in three human tumor cell lines, whereby the liposomal agents were superior vs. free complexes. DNA-fragmentation and flow cytometric assays showed that the cytotoxicity of free and liposomal salinomycinates is mediated by the induction of apoptosis and G1 arrest. The ability of the carriers to retain the bio-activity of the entrapped cargo gives us reason to conclude that the presented DPPC:CHOL:DSPE-PEG-2000 liposomes are suitable platforms for the salinomycin complexes, needing further evaluation and optimization