Bioelectrochemical removal of tetracycline from four typical soils in China: A performance assessment.

Exposure to tetracycline in soil causes microbial mutations. Soil microbial fuel cells (MFCs) can promote the degradation efficiency of contaminants while generating bioelectricity under anaerobic conditions. MFC performance varies amongst different types of soils due to distinctive soil properties. This study assesses the performance of soil MFCs filled with four typical Chinese soils and explores key factors regulating bioelectricity generation and tetracycline degradation. Except for the MFCs filled with black soil, tetracycline degradation rates improved in soil MFCs, particularly in those filled with Chao soil, which enhanced the degradation rate by 39% relative to the corresponding control. Additionally, soil MFCs filled with Chao soil exhibited the highest charge output of 1347 ±â€¯357C, which was 100-499% higher than that of MFCs with other soils. According to redundancy analysis, soil particle size, pH, conductivity and dissolved organic carbon content showed positive association with tetracycline degradation and charge output, while the adsorption of tetracycline had a negative association with degradation rate. Thus, the adsorption of tetracycline restricted its removal efficiency in soil MFCs, and high soil conductivity and large particle size promoted electron transfer, enhancing biocurrent intensity, which increased tetracycline degradation efficiency.

Ultrasound-assisted dispersive liquid-liquid microextraction of tetracycline drugs from egg supplements before flow injection analysis coupled to a liquid waveguide capillary cell.

A simple, rapid, and efficient ultrasound-assisted dispersive liquid-liquid microextraction (US-DLLME) method was developed for extraction of tetracycline residues from egg supplement samples, with subsequent determination by flow injection analysis (FIA) coupled to a liquid waveguide capillary cell (LWCC) and a controlled temperature heating bath. Tetracyclines react with diazotized p-sulfanilic acid, in a slightly alkaline medium, to form azo compounds that can be measured at 435 nm. The reaction sensitivity improved substantially (5.12-fold) using an in-line heating temperature of 45 °C. Multivariate methodology was used to optimize the factors affecting the extraction efficiency, considering the volumes of extraction and disperser solvents, sonication time, extraction time, and centrifugation time. Good linearity in the range 30-600 µg L(-1) was obtained for all the tetracyclines, with regression coefficients (r) higher than 0.9974. The limits of detection ranged from 6.4 to 11.1 µg L(-1), and the recoveries were in the range 85.7-96.4 %, with relative standard deviation lower than 9.8 %. Analyte recovery was improved by approximately 6 % when the microextraction was assisted by ultrasound. The results obtained with the proposed US-DLLME-FIA method were confirmed by a reference HPLC method and showed that the egg supplement samples analyzed were suitable for human consumption.