Sulfonamides are consumed as pharmaceutical antibiotics and reach agricultural soils with excreta used as fertilizer. Subsequently,
nonextractable residues rapidly form in soil, which has been researched in a couple of studies. To further elucidate conditions,
strength, and mechanisms of the fixation to soil humic substances, three selected sulfonamides were investigated using the
biochemical oligomerization of substituted phenols as a model for the humification process. Catechol, guaiacol, and vanillin were
enzymatically reacted using laccase from Trametes versicolor. In the presence of the substituted phenols alone, the concentration
of sulfonamides decreased. This decrease was even more pronounced when additional laccase was present. Upon the enzymatic
oligomerization of the substituted phenols to a humic-like structure the sulfonamides were sorbed, transformed, sequestered,
and nonextractable bound. Sulfonamides were transformed depending on their molecular properties. Fractions of different
bonding strength were determined using a sequential extraction procedure. Isolated nonextractable products were analyzed by
chromatographic, spectroscopic, and calorimetric methods to identify coupling and bonding mechanisms of the sulfonamides.
Differential scanning calorimetry measurements suggested cross-linking of such incorporated sulfonamides in humic oligomers.
Nuclear magnetic resonance spectroscopy measurements showed clear differences between the vanillin-sulfapyridine oligomer and
the parent sulfapyridine indicating bound residue formation through covalent binding.
Sulfonamides are consumed as pharmaceutical antibiotics and reach agricultural soils with excreta used as fertilizer. Subsequently,nonextractable residues rapidly form in soil, which has been researched in a couple of studies. To further elucidate conditions,strength, and mechanisms of the fixation to soil humic substances, three selected sulfonamides were investigated using thebiochemical oligomerization of substituted phenols as a model for the humification process. Catechol, guaiacol, and vanillin wereenzymatically reacted using laccase from Trametes versicolor. In the presence of the substituted phenols alone, the concentrationof sulfonamides decreased. This decrease was even more pronounced when additional laccase was present. Upon the enzymaticoligomerization of the substituted phenols to a humic-like structure the sulfonamides were sorbed, transformed, sequestered,and nonextractable bound. Sulfonamides were transformed depending on their molecular properties. Fractions of differentbonding strength were determined using a sequential extraction procedure. Isolated nonextractable products were analyzed bychromatographic, spectroscopic, and calorimetric methods to identify coupling and bonding mechanisms of the sulfonamides.Differential scanning calorimetry measurements suggested cross-linking of such incorporated sulfonamides in humic oligomers.Nuclear magnetic resonance spectroscopy measurements showed clear differences between the vanillin-sulfapyridine oligomer andบ่งชี้หลักซัลฟาไพริดีนผูกก่อสารตกค้าง โดยผูก covalent
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