Photodegradation of sulfasalazine and its human metabolites in water by UV and UV/peroxydisulfate processes.

The widespread occurrence of pharmaceuticals and their metabolites in natural waters has raised great concerns about their potential risks on human health and ecological systems. This study systematically investigates the degradation of sulfasalazine (SSZ) and its two human metabolites, sulfapyridine (SPD) and 5-aminosalicylic acid (5-ASA), by UV and UV/peroxydisulfate (UV/PDS) processes. Experimental results show that SPD and 5-ASA were readily degraded upon UV 254 nm direct photolysis, with quantum yields measured to be (8.6 ±â€¯0.8) × 10-3 and (2.4 ±â€¯0.1) × 10-2 mol Einstein-1, respectively. Although SSZ was resistant to direct UV photolysis, it could be effectively removed by both UV/H2O2 and UV/PDS processes, with fluence-based pseudo-first-order rate constants determined to be 0.0030 and 0.0038 cm2 mJ-1, respectively. Second-order rate constant between SO4•- and SSZ was measured as (1.33 ±â€¯0.01) × 109 M-1s-1 by competition kinetic method. A kinetic model was established for predicting the degradation rate of SSZ in the UV/PDS process. Increasing the dosage of PDS significantly enhanced the degradation of SSZ in the UV/PDS process, which can be well predicted by the developed kinetic model. Natural water constituents, such as natural organic matter (NOM) and bicarbonate (HCO3-), influenced the degradation of SSZ differently. The azo functional group of SSZ molecule was predicted as the reactive site susceptible to electrophilic attack by SO4•- by frontier electron densities (FEDs) calculations. Four intermediate products arising from azo bond cleavage and SO2 extrusion were identified by solid phase extraction-liquid chromatography-triple quadrupole mass spectrometry (SPE-LC-MS/MS). Based on the products identified, detailed transformation pathways for SSZ degradation in the UV/PDS system were proposed. Results reveal that UV/PDS could be an efficient approach for remediation of water contaminated by SSZ and its metabolites.

Biodegradation of sulfonamides by Shewanella oneidensis MR-1 and Shewanella sp. strain MR-4.

Because of extensive sulfonamides application in aquaculture and animal husbandry and the consequent increase in sulfonamides discharged into the environment, strategies to remediate sulfonamide-contaminated environments are essential. In this study, the resistance of Shewanella oneidensis MR-1 and Shewanella sp. strain MR-4 to the sulfonamides sulfapyridine (SPY) and sulfamethoxazole (SMX) were determined, and sulfonamides degradation by these strains was assessed. Shewanella oneidensis MR-1 and Shewanella sp. strain MR-4 were resistant to SPY and SMX concentrations as high as 60 mg/L. After incubation for 5 days, 23.91 ± 1.80 and 23.43 ± 2.98% of SPY and 59.88 ± 1.23 and 63.89 ± 3.09% of SMX contained in the medium were degraded by S. oneidensis MR-1 and Shewanella sp. strain MR-4, respectively. The effects of the initial concentration of the sulfonamides and initial pH of the medium on biodegradation, and the degradation of different sulfonamides were assessed. The products were measured by LC-MS; with SPY as a substrate, 2-AP (2-aminopyridine) was the main stable metabolite, and with SMX as a substrate, 3A5MI (3-amino-5-methyl-isoxazole) was the main stable metabolite. The co-occurrence of 2-AP or 3A5MI and 4-aminobenzenesulfonic acid suggests that the initial step in the biodegradation of the two sulfonamides is S-N bond cleavage. These results suggest that S. oneidensis MR-1 and Shewanella sp. strain MR-4 are potential bacterial resources for biodegrading sulfonamides and therefore bioremediation of sulfonamide-polluted environments.

Removal of sulfamethoxazole (SMX) and sulfapyridine (SPY) from aqueous solutions by biochars derived from anaerobically digested bagasse.

This study explored the sorption of sulfamethoxazole (SMX) and sulfapyridine (SPY) onto biochars produced from raw and anaerobically digested bagasse. Initial evaluation of six bagasse biochars showed that digested bagasse biochar prepared at 600 °C (DBG600) was the best adsorbent to remove SMX and SPY. Further laboratory batch sorption experiments showed that DBG600 adsorbed SMX and SPY from aqueous solution with maximum adsorption capacity of 54.38 and 8.60 mg g-1, respectively. Solution pH showed strong effect on the sorption ability of DBG600 to the two antibiotics, and the sorption decreased with increasing of solution pH. Experimental and model results suggested that adsorption of SMX and SPY onto DBG600 might be controlled by the π-π interaction.

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, Kd 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 Kd 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 pKa2. 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.

Novel strategy for sulfapyridine detection using a fully integrated electrochemical Bio-MEMS: Application to honey analysis.

Sulfapyridine (SPy) is a sulfonamide antibiotic largely employed as veterinary drugs for prophylactic and therapeutic purposes. Therefore, its spread in the food products has to be restricted. Herein, we report the synthesis and characterization of a novel electrochemical biosensor based on gold microelectrodes modified with a new structure of magnetic nanoparticles (MNPs) coated with poly(pyrrole-co-pyrrole-2-carboxylic acid) (Py/Py-COOH) for high efficient detection of SPy. This analyte was quantified through a competitive detection procedure with 5-[4-(amino)phenylsulfonamide]-5-oxopentanoic acid-BSA (SA2-BSA) antigens toward polyclonal antibody (Ab-155). Initially, gold working electrodes (WEs) of integrated biomicro electro-mechanical system (BioMEMS) were functionalized by Ppy-COOH/MNPs, using a chronoamperometric (CA) electrodeposition. Afterward, SA2-BSA was covalently bonded to Py/Py-COOH/MNP modified gold WEs through amide bonding. The competitive detection of the analyte was made by a mixture of a fixed concentration of Ab-155 and decreasing concentrations of SPy from 50µgL-1 to 2ngL-1. Atomic Force Microscopy characterization was performed in order to ensure Ppy-COOH/MNPs electrodeposition on the microelectrode surfaces. Electrochemical measurements of SPy detection were carried out using electrochemical impedance spectroscopy (EIS). This biosensor was found to be highly sensitive and specific for SPy, with a limit of detection of 0.4ngL-1. This technique was exploited to detect SPy in honey samples by using the standard addition method. The measurements were highly reproducible for detection and interferences namely, sulfadiazine (SDz), sulfathiazole (STz) and sulfamerazine (SMz). Taking these advantages of sensitivity, specificity, and low cost, our system provides a new horizon for development of advanced immunoassays in industrial food control.

Advanced oxidation of the antibiotic sulfapyridine by UV/H2O2: Characterization of its transformation products and ecotoxicological implications.

The aim of the present work is to investigate, under lab-scale conditions, the removal and transformation of the antibiotic sulfapyridine (SPY) upon advanced oxidation with UV/H2O2. High resolution mass spectrometry (HRMS) analyses by means of an ultra-high pressure liquid chromatography (UHPLC)-linear ion trap high resolution Orbitrap instrument (LTQ-Orbitrap-MS) were carried out in order to elucidate the different transformation products (TPs) generated. The abatement (>99%) of the antibiotic was only achieved after 180 min, highlighting its resilience to elimination and its potential persistence in the environment A total of 10 TPs for SPY were detected and their molecular structures elucidated by means of MS(2) and MS(3) scans. Finally, the combined ecotoxicity at different treatment times was evaluated by means of bioluminescence inhibition assays with the marine bacteria Vibrio fischeri.

Sorption and cosorption of lead and sulfapyridine on carbon nanotube-modified biochars.

New, sustainable, and low-cost materials that can simultaneously remove a range of wastewater contaminants, such as heavy metals and pharmaceutical residues, are needed. In this work, modified biochars were produced by dip-coating hickory or bagasse biomass in carbon nanotube (CNT) suspensions with or without sodium dodecylbenzenesulfonate (SDBS)-aided dispersion prior to slow pyrolysis in a N2 environment at 600 °C. The sulfapyridine (SPY) and lead (Pb) sorption ability of pristine hickory (HC) and bagasse (BC) biochars and the modified biochars with (HC-SDBS-CNT and BC-SDBS-CNT, respectively) and without (HC-CNT and BC-CNT) SDBS was assessed in laboratory aqueous batch single- and binary-solute system. The greatest removal of SPY and Pb was observed for HC-SDBS-CNT (86 % SPY and 71 % Pb) and BC-SDBS-CNT (56 % SPY and 53 % Pb), whereas HC-CNT, BC-CNT, and the pristine biochars removed far less. This can be attributed to the fact that surfactant could prevent the aggregation of CNTs and thus promote the distribution and stabilization of individual CNT nanoparticle on the biochar surface to adsorb the contaminants. The observation of no significant change in Pb sorption capacities of the surfactant-dispersed CNT-modified biochars in the presence of SPY, or vice versa, was indicative of site-specific sorption interactions and a lack of significant competition for functional groups by the two sorbates. These results suggest that products of hybrid technologies, such as biochars modified with CNTs, can yield multi-sorbents and may hold excellent promise as a sustainable wastewater treatment alternative.

Targeted adsorption of molecules in the colon with the novel adsorbent-based medicinal product, DAV132: A proof of concept study in healthy subjects.

During antibiotic treatments, active residuals reaching the colon profoundly affect the bacterial flora resulting in the emergence of resistance. To prevent these effects, we developed an enteric-coated formulated activated-charcoal based product, DAV132, meant to deliver its adsorbent to the ileum and neutralize antibiotic residues in the proximal colon. In a randomized, control, crossover study, the plasma pharmacokinetics of the probe drugs amoxicillin (500 mg) absorbed in the proximal intestine, and sulfapyridine (25 mg) metabolized from sulfasalazine in the cecum and rapidly absorbed, were compared after a single administration in 18 healthy subjects who had received DAV132, uncoated formulated activated charcoal (FAC) or water 16 and 8 hours before, concomitantly with the probe drugs, and 8 hours thereafter. The AUC0-96 h of amoxicillin was reduced by more than 70% when it was taken with FAC, but bioequivalent when it was taken with water or DAV132. By contrast, the AUC0-96 h of sulfapyridine was reduced by more than 90% when administered with either FAC or DAV132 in comparison with water. The results show that DAV132 can selectively adsorb drug compounds in the proximal colon, without interfering with drug absorption in the proximal small intestine, thereby constituting a proof of concept that DAV132 actually functions in humans.

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.

A new polymorph of N-(6-methylpyridin-2-yl)mesitylenesulfonamide.

A new polymorph is reported of the pharmaceutically active sulfapyridine derivative, N-(6-methylpyridin-2-yl)mesitylenesulfonamide, in the zwitterionic form 2-methyl-6-{[(2,4,6-trimethylbenzene)sulfonyl]azanidyl}pyridin-1-ium, C15H18N2O2S. The observed dimorphism is solvent dependent. The phase described previously [Beloso, Castro, García-Vázquez, Pérez-Lourido, Romero & Sousa (2003). Z. Anorg. Allg. Chem. 629, 275-284] crystallizes from ethanol and several other organic solvents, whereas the new form described here is obtained as a phase-pure product from methanol. The molecules in both dimorphic phases are very similar and adopt the conformation which is also predicted for an individual molecule by force field calculations. However, the two forms differ in their packing and hydrogen bonding. Results from solvent-assisted grinding indicate that the new form is less stable than the previously published phase.

Factors influencing antibiotics adsorption onto engineered adsorbents.

The study evaluated the adsorption of two antibiotics by four engineered adsorbents (hypercrosslinked resin MN-202, macroporous resin XAD-4, activated carbon F-400, and multi-walled carbon nanotubes (MWCNT)) from aqueous solutions. The dynamic results demonstrated the dominant influence of pore size in adsorption. The adsorption amounts of antibiotics on XAD-4 were attributed to the hydrophobic effect, whereas steric hindrance or micropore-filling played a main role in the adsorption of antibiotics by F-400 because of its high microporosity. Aside from F-400, similar patterns of pH-dependent adsorption were observed, implying the importance of antibiotic molecular forms to the adsorption process for adsorbents. Increasing the ionic concentration with CaC12 produced particular adsorption characteristics on MWCNT at pH 2.0 and F-400 at pH 8.0, which were attributed to the highly available contact surfaces and molecular sieving, respectively. Its hybrid characteristics incorporating a considerable portion of mesopores and micropores made hypercross linked MN-202 a superior antibiotic adsorbent with high adsorption capacity. Furthermore, the adsorption capacity of MWCNT on the basis of surface area was more advantageous than that of the other adsorbents because MWCNT has a much more compact molecular arrangement.

Interactions between carbon nanotubes and sulfonamide antibiotics in aqueous solutions under various physicochemical conditions.

Sulfamethoxazole (SMX) and sulfapyridine (SPY), two representative sulfonamide antibiotics, have attracted much attention recently because of their potential ecological risks. This work systematically investigated the adsorption characteristics of SMX and SPY on carbon nanotubes (CNTs), a newly introduced nano-adsorbent, under various physicochemical conditions. Laboratory batch adsorption experiments and mathematical models were used to determine the adsorption kinetics and isotherms of the two antibiotics to the CNTs. We found that SMX and SPY had very fast adsorption kinetics to the CNTs, which could be simulated with both the pseudo-second-order and the intraparticle diffusion models. These results suggest that the adsorption of the antibiotics to the CNTs were controlled by surface adsorption and intraparticle diffusion processes. Isotherm studies showed that sonication-aided dispersion slightly increased the adsorption of the antibiotics to the CNTs probably because the dispersion process might increase CNT surface area. When solution pH increased from 3.0 to 9.0, the Langmuir maximum sorption capacities of the antibiotics to the CNTs decreased from 98.0 to 18.6 mg/g (SMX) and from 108.6 to 83.2 mg/g (SPY), indicating pH is a controlling factor of the removal of the two antibiotics in aqueous solutions. We also found that the Langmuir adsorption capacity of the CNTs decreased slightly for both SMX and SPY when more adsorbents were in the solution. The findings from this study suggest that CNTs can be used as a high efficiency adsorbent to removal antibiotics from aqueous solution under various conditions.

Inhibitions on the behavior and growth of the nematode progeny after prenatal exposure to sulfonamides at micromolar concentrations.

Sulfonamides are one typical antibiotic which is an emerging hazardous material to the ecological stability due to their continuously application and biological effects to non-target organisms. The parent-progeny transgenerational effects need investigations to indicate their long-term consequences. Currently, we tested the transgenerational effects of sulfadiazine (SD), sulfapyridine (SP) and sulfamethazine (SMZ) on L3 larva of Caenorhabditis elegans. The nematodes were exposed to aqueous sulfonamides at micromolar concentrations for 96 h, and then the effects on the behavior and growth in the exposed parent and unexposed progeny were measured. Results showed that SD, SP and SMZ inhibited three behavior indicators including body bending frequency (BBF), reversal movement (RM) and Omega turn (OT), and the growth indicator (body length, BL). Behavior indicators showed higher sensitivities than the growth indicator, and BBF had the highest sensitivity among the behavior indicators. Moreover, the effects of sulfonamides were also observed in the unexposed progeny with partially rescued or more severe inhibitions on the indicators. The behavior also showed higher sensitivity than the growth in the progeny. The transgenerational effects of sulfonamides indicated that parental exposure can multiply the harmful effects of antibiotic pollution in following generations and their potential ecological risks at environmental concentrations were further raised.

Crystal structure, antibacterial and cytotoxic activities of a new complex of bismuth(III) with sulfapyridine.

A new complex of Bi(III) and sulfapyridine was synthesized and characterized by elemental analysis, atomic absorption spectrometry, conductivity analysis, electrospray ionization mass spectrometry (ESI-MS), infrared spectroscopy, and single crystal X-ray diffraction methods. The antimicrobial and the cytotoxic activities of the compound were investigated. Elemental and conductivity analyses are in accordance to the formulation [BiCl3(C11H11N3O2S)3]. The structure of the complex reveals a distorted octahedral geometry around the bismuth atom, which is bound to three sulfonamidic nitrogens from sulfapyridine, acting as a monodentate ligand, and to three chloride ions. The presence of the compound in solution was confirmed by ESI-MS studies. The complex is 3 times more potent than the ligand against Salmonella typhimurium, 4 times against Staphylococcus aureus, Shigella dysenteriae, and Shigella sonnei and 8 times more potent against Pseudomonas aeruginosa and Escherichia coli. The compound inhibits the growth of chronic myelogenous leukemia cells with an IC50 value of 44 µM whereas the free ligand has no effect up to 100 µM.

Removal of sulfamethoxazole and sulfapyridine by carbon nanotubes in fixed-bed columns.

Sulfamethoxazole (SMX) and sulfapyridine (SPY), two representative sulfonamide antibiotics, have gained increasing attention because of the ecological risks these substances pose to plants, animals, and humans. This work systematically investigated the removal of SMX and SPY by carbon nanotubes (CNTs) in fixed-bed columns under a broad range of conditions including: CNT incorporation method, solution pH, bed depth, adsorbent dosage, adsorbate initial concentration, and flow rate. Fixed-bed experiments showed that pH is a key factor that affects the adsorption capacity of antibiotics to CNTs. The Bed Depth Service Time model describes well the relationship between service time and bed depth and can be used to design appropriate column parameters. During fixed-bed regeneration, small amounts of SMX (3%) and SPY (9%) were irreversibly bonded to the CNT/sand porous media, thus reducing the column capacity for subsequent reuse from 67.9 to 50.4 mg g(-1) for SMX and from 91.9 to 72.9 mg g(-1) for SPY. The reduced column capacity resulted from the decrease in available adsorption sites and resulting repulsion (i.e., blocking) of incoming antibiotics from those previously adsorbed. Findings from this study demonstrate that fixed-bed columns packed with CNTs can be efficiently used and regenerated to remove antibiotics from water.

Enzyme-responsive controlled release of covalently bound prodrug from functional mesoporous silica nanospheres.

I want to break free: Mesoporous silica nanoparticles are functionalized with sulfasalazine (SZ; see scheme), a prodrug of 5-aminosalicylic acid (5-ASA) and sulfapyridine, to generate enzyme-responsive nanocarriers. In the presence of the colon-specific enzyme azo-reductase (orange), 5-ASA and sulfapyridine are efficiently released.

Insight into the role of dissolved organic matter in sorption of sulfapyridine by semiarid soils.

Sorption-desorption behavior of sulfapyridine was studied with three distinct soil types low in organic carbon with or without the introduction of exogenous dissolved organic matter (DOM). Experiments with bulk soils yielded sorption coefficients equivalent to those obtained with soils richer in organic matter, indicating an important sorptive role for soil mineral matrices. Cointroduction of sulfapyridine with DOM significantly reduced sulfapyridine sorption. However, decreasing solution pH from ~9 to ~6 limited the effect of DOM and revealed the effect of ionic speciation of sulfapyridine on the sorption potential. Sulfapyridine sorption to soils precoated with DOM exhibited contrasting trends. Two of the coated soils exhibited decreased sorption of sulfapyridine probably due to blockage of sorption sites by DOM. Conversely, the third soil demonstrated cumulative adsorption of sulfapyridine. Precoating also enhanced sulfapyridine desorption, suggesting that sorption of sulfapyridine to mineral surfaces involves stronger chemisorptive binding as compared with interactions with sorbed DOM. The capacity of soil to sorb DOM as well as the chemical fractionation of DOM during sorption were found to significantly affect binding of sulfapyridine. Competition between preferentially sorbed DOM moieties (e.g., carboxyl, phenol) and sulfapyridine for sorption sites is proposed. This study suggests that the chemical nature of DOM can significantly affect the fate of sulfonamide compounds in soils.

Biodegradation studies of N4-acetylsulfapyridine and N4-acetylsulfamethazine in environmental water by applying mass spectrometry techniques.

This work evaluates the biodegradation of N(4)-acetylsulfapyridine (AcSPY) and N(4)-acetylsulfamethazine (AcSMZ), metabolites of two of the most commonly used sulfonamides (SAs) in human and veterinary medicine, respectively. Aerobic transformation in effluent wastewater was simulated using aerated fixed-bed bioreactors. No visible changes in concentration were observed in the AcSMZ reactor after 90 days, whereas AcSPY was fully degraded after 32 days of experiment. It was also demonstrated that AcSPY transformed back to its parent compound sulfapyridine (SPY). The environmental presence of these two metabolites in wastewater effluent had been previously investigated and confirmed, together with three more SA acetylated metabolites and their corresponding parent compounds, in 18 different wastewater treatment plants in Hesse (Germany). Sulfamethoxazole (SMX) and SPY were the two SAs detected most frequently (90% and 89% of the samples, respectively) and in the highest concentrations (682 ng L(-1) for SMX and 532 ng L(-1) for SPY). To conclude, hazard quotients were calculated whenever toxicity data were available. None of the SAs studied posed an environmental risk.

Sulfapyridine-like benzenesulfonamide derivatives as inhibitors of carbonic anhydrase isoenzymes I, II and VI.

The inhibition of two human cytosolic carbonic anhydrase (hCA, EC 4.2.1.1) isozymes I, II and human serum isozyme VI, with a series of tosylited aromatic amine derivatives was investigated. The K(I) ranges of compounds 1-14 and acetazolamide against hCA I ranged between 1.130 and- 448.2 µM, against hCA II between 0.103 and- 14.3 µM, and against hCA VI ranged between 0.340 and- 42.39 µM. Tosylited aromatic amine derivatives are thus interesting hCA I, II and VI inhibitors, and might be used as leads for generating enzyme inhibitors eventually targeting other isoforms which have not been assayed yet for their interactions with such agents.

Kinetic studies and characterization of photolytic products of sulfamethazine, sulfapyridine and their acetylated metabolites in water under simulated solar irradiation.

Sulfapyridine (SPY), sulfonamide (SA) typically used in human therapies, and veterinary SA sulfamethazine (SMZ), are amongst the two SAS most frequently detected in effluent wastewater and surface water respectively. Within this context, this study reports the behaviour of both SAs and their acetylated metabolites, AcSPY and AcSMZ, under artificial irradiance conditions in both high performance liquid chromatography (HPLC) water and in reclaimed wastewater, in order to compare the influence of dissolved organic matter (DOM) and also inorganic matter in the photolysis kinetics. Estimated degradation rate constants (k) ranged from 0.063 h(-1) (SPY) to 2.808 h(-1) (AcSPY), both in HPLC water, with corresponding half-lives (t(1/2)) of 10.93 h and 0.25 h, respectively. A total of 10 different photodegradation products were identified during the photolytic transformation of SPY and 7 for SMZ, through ultra-performance liquid chromatography-quadrupole time of flight mass spectrometry analyses (UPLC-QqTOF-MS), which allowed for exact mass measurements. Regarding the acetylated metabolites, 3 photoproducts were generated for AcSMZ and one for AcSPY. The desulfonated products of each of the four analytes under study were the most relevant photodegradation products identified.