Potentiometric determination of acid dissociation constants (pKa) for human and veterinary antibiotics.

Conventional drinking water treatment processes were evaluated under typical water treatment plant conditions to determine their effectiveness in the removal of seven common antibiotics: carbadox, sulfachlorpyridazine, sulfadimethoxine, sulfamerazine, sul- famethazine, sulfathiazole, and trimethoprim. Experiments were conducted using synthetic solutions prepared by spiking both distilled/ deionized water and Missouri River water with the studied compounds. Sorption on Calgon WPH powdered activated carbon, reverse osmosis, and oxidation with chlorine and ozone under typical plant conditions were all shown to be effective in removing the studied antibiotics. Conversely, coagulation/flocculation/sedimentation with alum and iron salts, excess lime/soda ash softening, ultraviolet irra- diation at disinfection dosages, and ion exchange were all relatively ineffective methods of antibiotic removal. This study shows that the studied antibiotics could be effectively removed using processes already in use in many water treatment plants. Additional work is needed on by-product formation and the removal of other classes of antibiotics.

Removal of Antibiotics from Surface and Distilled Water in Conventional Water Treatment Processes

Removal of Pharmaceutical and Personal Care Products (PPCPs) under nitrifying and denitrifying conditions

The acid dissociation constant is an important physicochemical parameter of a substance, and knowledge of it is of fundamental importance in a wide range of applications and research areas. We present a critical review of published methods and approaches for the determination of acid dissociation constants, with a special emphasis on the p K a values of active pharmaceutical ingredients.

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Determination of pKa values of active pharmaceutical ingredients

Adsorption of ionizable compounds by black carbon is poorly characterized. Adsorption of the veterinary antibiotic sulfamethazine (SMT; a.k.a., sulfadimidine; pKa1 = 2.28, pKa2 = 7.42) on a charcoal was determined as a function of concentration, pH, inorganic ions, and organic ions and molecules. SMT displayed unconventional adsorption behavior. Despite its hydrophilic nature (log Kow = 0.27), the distribution ratio Kd at pH 5, where SMT0 prevails, was as high as 106 L kg–1, up to 104 times greater than literature reported Koc. The Kd decreases at high and low pH but not commensurate with the decline in Kow of the ionized forms. At pH 1, where SMT+ is predominant and the surface is positive, a major driving force is π–π electron donor–acceptor interaction of the protonated aniline ring with the π-electron rich graphene surface, referred to as π+–π EDA, rather than ordinary electrostatic cation exchange. In the alkaline region, where SMT– prevails and the surface is negative, adsorption is accompanied by n...

Speciation of the Ionizable Antibiotic Sulfamethazine on Black Carbon (Biochar)

Migration behavior and separation of sulfonamides in capillary zone electrophoresis III. Citrate buffer as a background electrolyte

Migration behavior and selectivity of sulfonamides in capillary electrophoresis

Migration behavior and separation of sulfonamides in capillary zone electrophoresis. I. Influence of buffer pH and electrolyte modifier.

Migration behaviour and selectivity of dichlorophenols in micellar electrokinetic capillary chromatography Influence of micelle concentration and buffer pH

Wei-Chen Lin

Papers

Migration behavior and separation of sulfonamides in capillary zone electrophoresis III. Citrate buffer as a background electrolyte

Migration behavior and selectivity of sulfonamides in capillary electrophoresis

Migration behavior and separation of sulfonamides in capillary zone electrophoresis. I. Influence of buffer pH and electrolyte modifier.

Migration behaviour and selectivity of dichlorophenols in micellar electrokinetic capillary chromatography Influence of micelle concentration and buffer pH

Capillary zone electrophoretic separation of alkylbenzyl quaternary ammonium compounds: effect of organic modifier