In this article, we propose a method of recovering p-MePhSO3K from the industrial by-product of quizalofop-p-ethyl. The phase diagram of the solid–liquid equilibrium system of p-MePhSO3K2CO3–H2O at the temperatures of 15, 25, 35, 45, and 55 °C was determined and plotted. Based on the phase diagram of 25 °C, the separation and recovery process of p-MePhSO3K from the p-MePhSO3K2CO3–H2O system was designed by analyzing the crystallization fields. First, p-MePhSO3K and K2CO3 were crystallized from wastewater in turn through evaporation separation. Then, the crystallized p-MePhSO3K was purified further by washing with ethanol. Finally, the pure p-MePhSO3K was transformed into the intermediate p-toluenesulfonyl chloride and then the intermediate l-p-toluenesulfonate ethyl lactate for quizalofop-p-ethyl production.
A natural consortium, named L1, of Rhodococcus sp. JT-3 and Brevundimonas sp. JT-9 was obtained from quizalofop- p -ethyl (QE) polluted soil. The consortium was able to use QE as a sole carbon source for growth and degraded 100 mg L −1 of QE in 60 h. Strain JT-3 initiated the catabolism of QE to quizalofop acid (QA), which was used by strain JT-9 as carbon source for growth and to simultaneously feed strain JT-3. A novel esterase EstS-JT, which was responsible for the transformation of QE to QA and essential for the mineralization of QE by the consortium, was cloned from strain JT-3. EstS-JT showed low amino acid identity to other reported esterases from esterase family VIII and represents a new member of this family. The deduced amino acid sequence contained the esterase family VIII conserved motifs S-X-X-K, YSV and WAG. The purified recombinant EstS-JT displayed maximal esterase activity at 35 °C and pH 7.5. An inhibitor assay, site-directed mutagenesis and 3D modeling analysis revealed that S 64 , K 67 and Y 175 were essential for catalysis and probably comprised the catalytic center of EstS-JT. Additionally, EstS-JT had broad substrate specificity and was capable of hydrolyzing p -nitrophenyl esters (C 2 -C 8 ) and various AOPP herbicides.
Quizalofop-p-ethyl is a widely used herbicide that poses a threat to human health and environmental safety. In this study, anti-quizalofop-p-ethyl monoclonal antibodies (mAbs) were prepared and used to develop a gold nanoparticle-based lateral flow immunoassay (AuNP-LFIA) for the detection of quizalofop-p-ethyl in agriproducts and environmental samples. Four hybridoma cell lines were obtained, among which 5B6D10E11 secreted mAb with the highest sensitivity, with a 50 % inhibition concentration of 4.57 ng/mL in the indirect competitive enzyme-linked immunosorbent assay. After optimization, the AuNP-LFIA strip based on the mAb (5B6D10E11) showed a visual detection limit of 10 ng/mL, and the results could be directly determined by the naked eye within 8 min. The cross-reactivity of the AuNP-LFIA for analogs of quizalofop-p-ethyl was negligible except for quizalofop-p-acid. The established AuNP-LFIA was proven to be accurate and precise based on the recovery test. Furthermore, the detection results of AuNP-LFIA were consistent with those of ultra-high-performance liquid chromatography tandem mass spectrometry.
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