Performance of restricted access copper-imprinted poly(allylthiourea) in an on-line preconcentration and sample clean-up FIA-FAAS system for copper determination in milk samples.

A new on-line solid phase preconcentration method using an ion-imprinted polymer with restrict access material based on copper-imprinted poly(allylthiourea) modified with 2-hydroxyethyl methacrylate and bovine serum (IIP-HEMA-BSA) to preconcentrate Cu2+ ions and exclude protein from milk samples via FIA-FAAS was developed. The samples were on-line preconcentrated at pH 4.5 through a mini-column packed with 50.0 mg of IIP-HEMA-BSA at a flow rate of 7.6 mL min-1 followed by a counter-current elution with 1.00 mol L-1 HCl towards the FAAS detector. The interference of ions commonly found in milk samples and the presence of BSA were investigated in the Cu2+ ions preconcentration. The method provided an analytical curve ranging from 3.6 to 100.0 µg L-1, preconcentration factor of 24-fold, limit of detection of 1.1 µg L-1 and sample throughput of 20 h-1. The accuracy of the method was attested by Cu2+ ions addition/recovery tests as well as by using GFAAS of samples microwave-assisted digested. The proposed method was successfully applied to the copper determination in milk samples, requiring only pH adjustment followed by preconcentration step as sample pretreatment. Copper content in bovine milk sample was 0.635 ±â€¯0.042 mg kg-1, while to soybean milk samples were between 0.048 ±â€¯0.008 and 0.094 ±â€¯0.005 mg kg-1. To the best of our knowledge, the potential of IIP-HEMA-BSA for Cu2+ ions extraction from biological samples and simultaneous removal of macromolecules employing minimal sample pretreatment was demonstrated for the first time. The proposed extraction method stands out by being simple, fast and a low-cost analytical strategy when compared to the conventional microwave-assisted acid digestion.

Development of new analytical method for preconcentration/speciation of inorganic antimony in bottled mineral water using FIA-HG AAS system and SiO2/Al2O3/SnO2 ternary oxide.

In the present paper, a new analytical preconcentration/speciation method for antimony species determination in bottled mineral water samples using the SiO2/Al2O3/SnO2 adsorbent was developed. The method is based on selective adsorption of Sb(III) ions by SiO2/Al2O3/SnO2 under a wide pH range (2.5-7.5). Total antimony was determined with previous sample treatment using 0.1% (w/v) l-cysteine and the concentration of Sb(V) species was determined by the difference between total and Sb(III). The proposed method provided an analytical curve ranging from 0.50 to 5.00 µg L-1 (r = 0.999), limit of detection (LD) of 0.17 µg L-1 and preconcentration factor (PF) of 136-fold. The method exhibited tolerance to different metal ions and the accuracy was attested from addition and recovery tests (95.2-106.0%) in bottled mineral water samples using 2.0% (w/v) l-cysteine, as well as by analysis of certified material. Only Sb(III) species were determined in mineral water (0.54-1.04 µg L-1).

Adsorption mechanism of chromium(III) using biosorbents of Jatropha curcas L.

The removal of Cr3+ from water solutions by biosorbents from the rind, endosperm, and endosperm + episperm of the Jatropha curcas was evaluated. Adsorption tests were performed in batch systems for evaluating the influence of the solution's pH, adsorbent mass, contact time, initial Cr3+ concentrations, and solution temperature during the adsorption process. Kinetic, adsorption isotherm, and thermodynamic studies were performed to investigate the mechanisms that control adsorption. Ideal conditions for the adsorption process included pH of the solution of 5.5 and 8 g L-1 adsorbent mass, within 60 min time contact between adsorbent and adsorbate. Maximum adsorption capacities by Langmuir model for rind, endosperm, and endosperm + episperm of the J. curcas were, respectively, 22.11, 18.20, and 22.88 mg g-1, with the occurrence of chemosorption in mono and multilayers. Results show that the biosorbents obtained from J. curcas have a high potential to recuperate Cr3+ from contaminated water sources.