Ball milled biochar effectively removes sulfamethoxazole and sulfapyridine antibiotics from water and wastewater

Release of antibiotics into the environment, which often occurs downstream of wastewater treatment plants, poses a human health threat due to the potential development of bacterial antibiotic resistance. In this study, laboratory experiments were conducted to evaluate the performance of ball milled biochar on the removal of two sulfonamide antibiotics, sulfamethoxazole (SMX) and sulfapyridine (SPY) from water and wastewater. Aqueous batch sorption experiment using both pristine and ball milled biochar derived from bagasse (BG), bamboo (BB) and hickory chips (HC), made at three pyrolysis temperatures (300, 450, 600 °C), showed that ball milling greatly enhanced the SMX and SPY adsorption. The 450 °C ball milled HC biochar and BB biochar exhibited the best removal efficiency for SMX (83.3%) and SPY (89.6%), respectively. A range of functional groups were produced by ball milling, leading to the conclusion that the adsorption of sulfonamides on the biochars was controlled by multiple mechanisms including hydrophobic interaction, π-π interaction, hydrogen bonding, and electrostatic interaction. Due to the importance of electrostatic interaction, SMX and SPY adsorption was pH dependent. In laboratory water solutions, the Langmuir maximum adsorption capacities of SMX and SPY reached 100.3 mg/g and 57.9 mg/g, respectively. When tested in real wastewater solution, the 450 °C ball milled biochar still performed well, especially in the removal of SPY. The maximum adsorption capacities of SMX and SPY in wastewater were 25.7 mg/g and 58.6 mg/g, respectively. Thus, ball milled biochar has great potential for SMX and SPY removal from aqueous solutions including wastewater.

Adsorption of sulfamethoxazole and sulfapyridine antibiotics in high organic content soils

Many antibiotics, including sulfonamides, are being frequently detected in soil and groundwater. Livestock waste is an important source of antibiotic pollution, and sulfonamides may be present along with organic-rich substances. This study aims to investigate the sorption reaction of two sulfonamides, sulfamethoxazole (SMZ) and sulfapyridine (SPY) in two organic-rich sorbents: a commercial peat soil (38.41% carbon content) and a composted manure (24.33% carbon content). Batch reactions were conducted to evaluate the impacts of pH (4.5-9.5) and background ions (0.001 M-0.1 M CaCl₂) on their sorption. Both linear partitioning and Freundlich sorption isotherms fit the reaction well. The n values of Freundlich isotherm were close to 1 in most conditions suggesting that the hydrophobic partition is the major adsorption mechanism. In terms of SMZ, K_d declined with increases in the pH. SPY has a pyridine group that is responsible for adsorption at high pH values, and thus, no significant trend between K_d and pH was observed. At high pH ranges, SPY sorption deviated significantly from linear partitioning. The results suggested the sorption mechanism of these two sulfonamide antibiotics tended to be hydrophobic partitioning under most of the experimental conditions, especially at pH values lower than their corresponding pK_a2. The fluorescence excitation emission matrix and dissolved organic carbon leaching test suggested composted manure has higher fulvic acid organics and that peat soil has higher humus-like organics. Small organic molecules showed stronger affinity toward sulfonamide antibiotics and cause the composted manure to exhibit higher sorption capacity. Overall, this study suggests that the chemical structure and properties of sulfonamides antibiotics and the type of organic matter in soils will greatly influence the fate and transport of these contaminants into the environment.

Photodegradation of sulfapyridine under simulated sunlight irradiation: kinetics, mechanism and toxicity evolvement

In this study, the photoinduced degradation of sulfapyridine (SPY) was investigated under simulated light irradiation (λ>200nm). The effect of pH and main water constituents including nitrate ion, bicarbonate, dissolved organic matter (DOM) and iron(III) on the photodegradation was explored. SPY was effectively removed in aqueous solution at pH 8 under UV-vis irradiation, with removal efficiency of 100% within 120min. DOM and iron(III) had retarding influence on the SPY removal, whereas nitrate ion and bicarbonate did not show any obvious effect. Under UV-vis irradiation, the formation of singlet oxygen ((1)O2) accelerated the SPY photodegradation and the contribution of indirect photolysis due to reaction with (1)O2 was up to 42%. The transformation products of SPY were identified by HPLC-MS and the possible photoreaction pathways were proposed. It showed that photoinduced hydrolysis, photo-oxidation via (1)O2 and desulfonation were the main degradation ways for SPY decomposition. Toxicity assays by Vibrio fischeri proved that the transformation products were more toxic than the parent compound.

Occurrence and source apportionment of sulfonamides and their metabolites in Liaodong Bay and the adjacent Liao River basin, North China

The presence of antibiotics in the environment is of great concern because of their potential for resistance selection among pathogens. In the present study we investigated the occurrence of 19 sulfonamides, five N-acetylated sulfonamide metabolites, and trimethoprim in the Liao River basin and adjacent Liaodong Bay, China, as well as 10 human/agricultural source samples. Within the 35 river samples, 12 sulfonamides, four acetylated sulfonamides, and trimethoprim were detected, with the dominant being sulfamethoxazole (66.6 ng/L), N-acetylsulfamethoxazole (63.1 ng/L), trimethoprim (29.0 ng/L), sulfadiazine (14.0 ng/L), and sulfamonomethoxine (8.4 ng/L); within the 36 marine samples, 10 chemicals were detected, with the main contributions from sulfamethoxazole (25.2 ng/L) and N-acetylsulfamethoxazole (28.6 ng/L). Sulfamethoxazole (25.9%), N-acetylsulfamethoxazole (46.6%), trimethoprim (22.9%), and sulfapyridine (1.4%) were the main chemicals from human sources, while sulfamonomethoxine, sulfamethazine, sulfaquinoxaline, sulfaguanidine, sulfadiazine, sulfanilamide, and sulfamethoxypyridazine were dominant in the animal husbandry sources, specifically, swine and poultry farms, and sulfamethoxazole (91%) was dominant in the mariculture source. A principal component analysis with multiple linear regression was performed to evaluate the source apportionment of total sulfonamides in Liaodong Bay. It was found that animal husbandry contributed 15.2% of total sulfonamides, while human sources contributed 28.5%, and combined human and mariculture sources contributed 56.3%. In addition, the mariculture contribution was 24.1% of total sulfonamides into the sea based on mass flux estimation. The present study is the first report that the environmental levels of sulfonamide metabolites were comparable to the corresponding parents; therefore, we should pay attention to their environmental occurrence. Source apportionment showed human discharge (60.7%) significantly contributed to these antibiotics in Liaodong Bay, which provides important information for environmental management.

[Qualification and quantification of 10 sulfonamides in animal feedstuff by high performance liquid chromatography-electrospray tandem mass spectrometry]

The presence of sulfonamide (SA) residues in foods is largely due to the raising of animals with sulfonamide antibiotics added or polluted feedstuff. Because of interference from the matrices, the commonly used immunoassay or chromatographic method is not suitable for the analysis of multi-SAs in feedstuff. A high performance liquid chromatographic-electrospray tandem mass spectrometric (HPLC/ESI-MS-MS) method has been established for the simultaneous determination of multi-SAs including sulfadiazine (SD), sulfapyridine (SPD), sulfamerazine (SM1), sulfameter (SM), sulfamethazine (SM2), sulfamethoxypyridazine (SMP), sulfamethoxazole (SMZ), sulfamonomethoxine (SMM), sulfadimethoxine (SDM) and sulfaquinoxaline (SQX). After solvent extraction, solid phase extraction, dilution and reversed-phase HPLC separation, SAs were detected by ESI-MS-MS under multi-reaction monitoring mode. The qualification analysis was done by using retention time and distribution of diagnostic ion pairs, and the quantification was based on the peak intensity of common fragment ion m/z 156. The limits of quantification for 10 SAs were 0.5 - 2.0 microg/kg (S/N = 10). The correlation coefficient of linear calibration curve was over 0.9995 within the SAs concentration range 2.0 - 200 microg/L except for SDM and SQX. At the spiked level of 1.0 mg/kg, the average recoveries for the 10 SAs were between 70% and 92%, the relative standard deviations were under 10% for intra-day and under 15% for inter-day. Routine tests showed the method was fast, sensitive, specific, and practical for the SAs determination in feedstuff.

Microbial inhibition by pharmaceutical antibiotics in different soils--dose-response relations determined with the iron(III) reduction test

Soil contamination from pharmaceuticals is an emerging problem, though quantitative data on their microbial effects are lacking. Thus, nine pharmaceutical antibiotics were tested for their effects on the microbial iron(III) reduction in six different topsoils. Complete dose-response curves were obtained and best-fit by sigmoidal Logit, Weibull, Box-Cox Logit, and Box-Cox Weibull equations (r2 0.73-1.00). The derived effective doses (ED [micromol/kg soil]) for the different antibiotics increased in the order (average ED50 in parentheses) chlortetracycline (53) < sulfadimethoxine (58) < oxytetracycline (170) < sulfadiazine (190) < sulfadimidine (270) = tetracycline (270) < sulfapyridine (430), though no effect was found for sulfanilamide and fenbendazole at doses up to 5,800 and 3,300 micromol/kg, respectively. Due to a strong soil adsorption, especially of the tetracyclines, the corresponding effective concentrations in the soil solution (EC50), derived from sorption experiments, were considerably smaller and ranged from 0.004 micromol/L (chlortetracycline) to 120 micromol/L (sulfapyridine). The effects of the antibiotics were governed by soil sorptive properties, especially the concentration of soil organic matter. The microbial inhibition was influenced indirectly by the soil pH, which affects the ionization status of the amphoteric antibiotics.

Obstructive nephropathy secondary to sulfasalazine calculi

The incidence of drug-induced stone disease is 0.44%. A 57-year-old woman with ulcerative colitis presented with obstructive nephropathy and pyelonephritis. She underwent cystoscopy, bilateral retrograde pyelography, and bilateral ureteral stent placement. A 6-cm bladder calculus and two 3-mm right distal ureteral calculi were discovered. Later, cystolithotomy was performed. The stone analysis demonstrated sulfapyridine, a sulfasalazine metabolite. Patients with inflammatory bowel disease can develop urolithiasis owing to acidic urine and low-volume urine production. Patients receiving aminosalicylates are at an increased risk of urolithiasis and may benefit from oral hydration and urinary alkalization.

[A case of drug induced urolithiasis composed of acetyl sulphapyridine associated with ulcerative colitis]

A 26-year-old female visited our hospital complaining left flank pain and macroscopic hematuria. She had been suffering ulcerative colitis and administered salazosulphapyridine and predonisolone from 17-year-old. Intravenous urography showed radiolucent multiple stones in the left renal pelvis. Three sessions of extracorporeal shock wave lithotripsy were performed after ureteral stenting. Although disintegration and discharge of the stones were satisfactory, bladder stone induced by ureteral stent was complicated. The extracted bladder stone showed a yellowish brown color and the surface was granular shape. Composition of the stone was acetyl sulphapyridine which was a metabolite of salazosulphapyridine. After maintenance of the urinary pH ranges between 6.5 and 7.5 by medication of sodium bicarbonate, the patient remains free of stone for 3 years. Drug induced urolithiasis originated from salazosulphapyridine is extremely rare. Satisfactory oral fluid intake and urinary alkalization are important for prevention of sulpha drugs calculi of urinary tract.

Bilateral acetylsulfapyridine nephrolithiasis associated with chronic sulfasalazine therapy

We report on formation of bilateral renal calculi secondary to sulfasalazine therapy for juvenile rheumatoid arthritis. The condition was successfully treated with extracorporeal shock wave lithotripsy. Analysis of the fragments with thin layer chromatography and nuclear magnetic resonance revealed acetylsulfapyridine, a metabolite of sulfasalazine.

Development of a screening method for five sulfonamides in salmon muscle tissue using thin-layer chromatography

A thin-layer chromatographic (TLC) method was developed for the analysis of five sulfonamides [sulfadiazine (SDZ), sulfamerazine (SMRZ), sulfamethazine (SMTZ), sulfadimethoxine (SDMX) and sulfapyridine (SP)] in salmon muscle tissue. "Matrix solid-phase dispersion" was employed whereby the tissue sample was ground with C18-derivatized silica gel. This material was packed into a column and washed with 10% toluene in hexane (discarded) followed by dichloromethane which was evaporated. The residue was chromatographed on a high-performance TLC plate using ethyl acetate-n-butanol-methanol-aqueous ammonia (35:45:15:2, v/v). Sulfonamides were detected after spraying the plate with a solution of fluorescamine. Method parameters were determined by analyzing spiked salmon muscle tissue samples. The method detection limits at the 99% confidence level were 0.11, 0.44, 0.07, 0.13 and 0.13 ppm for SDZ, SMRZ, SMTZ, SDMX and SP, respectively. The lowest-detectable levels were approximately 0.04 ppm for SDZ, SMTZ, SDMX and SP, and 0.10 ppm for SMRZ. The average recoveries of analyses were 61, 63, 60, 63 and 57% for SDZ, SMRZ, SMTZ, SDMX and SP, respectively, and were found to be analyst-dependent. The method was found to give linear detector responses for all analytes over spiking levels ranging from 0 to 2 ppm.

Conformational polymorphism VI: the crystal and molecular structures of form II, form III, and form V of 4-amino-N-2-pyridinylbenzenesulfonamide (sulfapyridine)

The crystal structures of three crystalline forms of 4-amino-N-pyridinylbenzenesulfonamide (sulfapyridine) have been determined by X-ray single crystal structure analysis. Form II crystallizes in space group P2(1)/c with four molecules in the unit cell: a = 0.6722(1) nm, b = 2.0593(5) nm, c = 0.8505(1) nm, beta = 101.14(1) degrees; Form III crystallizes in space group C2/c with eight molecules in the unit cell: a = 1.2830(2) nm, b = 1.1714(3) nm, c = 1.5400(3) nm, beta = 94.12(1) degrees; Form V crystallizes in the orthorhombic space group Pbca with 16 molecules in the unit cell: a = 2.4722(10) nm, b = 1.5710(15) nm, c = 1.2147(7) nm. The three structures were solved by direct methods and refined anisotropically to R factors of 0.045, 0.052, and 0.063, respectively. Bond lengths and bond angles agree well among the molecules in these structures; however, the system exhibits conformational polymorphism since the molecular conformation, as measured by torsion angles, differs significantly among the three forms. Sulfapyridine exhibits the imide configuration in all three structures rather than the amide form present in other sulfonamide compounds. Using the structural data, the powder patterns of the three forms have been computer generated to provide standard diffraction patterns for comparison with the variety of polymorphic forms reported in the literature.

High-performance liquid chromatographic assay of sulfapyridine and acetylsulfapyridine in biological fluids

A high-pressure liquid chromatographic method for the sensitive, rapid, and specific determination of sulfapyridine and its N-acetyl derivative in plasma and saliva was developed. A cyano-bonded, reversed-phase, high efficiency column was used. The system detected these sulfonamides in serum to 0.25 mg/liter and within only 6 min. Sulfapyridine was separated from its acetyl derivative with little interference from other drugs. The assay reproducibility was within 3%. The assay was highly useful for routine monitoring of patients receiving sulfasalazine for inflammatory bowel disease.