Specific Structure and Properties of Composite Membranes Based on the Torlon® (Polyamide-imide)/Layered Perovskite Oxide

The use of perovskite-type layered oxide K2La2Ti3O10 (Per) as a modifier of the Torlon® polyamide-imide (PAI) membrane has led to the formation of an specific structure of a dense nonsymmetrical film, namely, a thin perovskite-enriched layer (3–5 μm) combined with the polymer matrix (~30 μm). The PAI/Per membrane structure was studied by SEM in combination with energy dispersive microanalysis of the elemental composition which illustrated different compositions of top and bottom surfaces of the perovskite-containing membranes. Measurement of water and alcohol contact angles and calculation of surface tension revealed hydrophilization of the membrane surface enriched with perovskite. The transport properties of the nonsymmetrical PAI/Per membranes were studied in the pervaporation of ethanol‒ethyl acetate mixture. The inclusion of 2 wt.% Per in the PAI gives a membrane with a high separation factor and increased total flux.

ELISA validation and determination of cut-off level for chloramphenicol (CAP) residues in shrimp and fish

An analytical validation of enzyme-linked immunosorbent assay (ELISA) screening for detection of chloramphenicol (CAP) in shrimp and fish was conducted according to the Commission Decision 2002/657/EC and guidelines for the validation of screening methods for residues of veterinary medicines. The analyte was extracted from shrimp and fish with ethyl acetate mixture, and CAP concentrations were measured photometrically at 450 nm. The recovery rate of the analyte from spiked samples was 80%. For the laboratory the cut-off level of CAP in fish and shrimp as the minimum recovery was established along with detection capability (CCβ). No relevant interferences between matrix effects and structurally related substances including florfenicol and thiamphenicol were observed. The experimental results were quite satisfactory and ELISA method was found very useful for determination of CAP residues in shrimp and fish monitoring.

ELISA validation and determination of cut-off level for chloramphenicol residues in honey

An analytical validation of a screening ELISA for detection of chloramphenicol (CAP) in honey was conducted according to the Commission Decision 2002/657/EC and Guidelines for the Validation of Screening Methods for Residues of Veterinary Medicines. The analyte was extracted from honey with a water and ethyl acetate mixture, and CAP concentrations were measured photometrically at 450 nm. The recovery rate of the analyte from spiked samples was 79%. The cut-off level of CAP in honey as the minimum recovery (0.17 units) was established. Detection capability (CCβ) was fixed at 0.25 μg kg−1. No relevant interferences between matrix effects and structurally related substances including florfenicol and thiamphenicol were observed. The ELISA method should be useful for determination of CAP residues in honey monitoring.