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The structure of 2,4-(4'-aminobenzenamine)pyrimidine (1), a pyrimidine alkaloid previously isolated from the bulbs of Scilla madeirensis (Asparagaceae, synonym Autonoë madeirensis), has been revised. These conclusions were met via comparison of reported NMR and EIMS data with those obtained from synthetic standards. The corrected structure is the antibiotic sulfadiazine (2), which has likely been isolated as a contaminant from the site of collection. The reported bioactivity of 1 as an α1-adrenoceptor antagonist should instead be ascribed to sulfadiazine. Our findings appear to show another example of an anthropogenic contaminant being identified as a natural product and emphasize the importance of considering the biosynthetic origins of isolated compounds within a phylogenetic context.

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The potential of horseradish peroxidase (HRP) to catalyze the removal of sulfonamides from water and the effects of different H2O2 and HRP concentrations were investigated. Six sulfonamides, each with a five- or six-membered heterocyclic group, including sulfamethoxazole (SMX), sulfathiazole (STZ), sulfapyridine (SPD), sulfadiazine (SDZ), sulfamerazine (SMR) and sulfamethoxypyridazine (SMP) were selected as target compounds. All sulfonamides exhibit a pseudo-first-order dependence of the concentration versus the reaction time. The decay rate (k, h-1) of the six sulfonamides spiked individually exhibit a trend following the order of STZ > SMP, SPD > SMR > SDZ ¼â€¯SMX. When spiked together, the coexistent sulfonamides might act as mediators for the enhancement of SMX removal and as competitors for the decreased removal of most sulfonamides. Moreover, six transformation products of SDZ are identified by the Thermo Scientific LTQ Orbitrap Elite technique. SDZ transformation involves two steps: one is the Smiles re-arrangement of the structure, and the other is oxidation and sulfur dioxide extrusion. This study is the first to report the removal dynamics of sulfonamides in HRP-catalyzed reactions and the identified products of SDZ.

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This study presents a novel, simple and efficient pseudo-stir bar solid phase microextraction method for separation and preconcentration of sulfadiazine. To develop the method, a graphene oxide-silica composite reinforced hollow fiber was prepared via sol-gel technology and used as a novel device to extract sulfadiazine. The retained sulfadiazine was eluted using 180µL of methanol/acetic acid (6:4) and quantified by fiber optic linear array spectrophotometry based on the formation of its azo dye with thenoyltrifluoroacetone. Under optimized conditions, the method exhibited a linear dynamic range of 5-150µgL-1 with a detection limit of 1.5µgL-1 and an enrichment factor of 100. The relative standard deviations of 2.9% and 5.8% (n=6) were obtained at 60µgL-1 level of sulfadiazine for intra- and inter-day analysis respectively. The method was successfully applied to determine sulfadiazine in honey, milk, human urine and environmental water samples.

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Polyoxyethylene lauryl ether (POELE10)-Na2C4H4O6 aqueous two-phase extraction system (ATPES) is a novel and green pretreatment technique to trace samples. ATPES coupled with high-performance liquid chromatography (HPLC) is used to analyze synchronously sulfadiazine (SDZ) and sulfamethazine (SMT) in animal by-products (i.e., egg and milk) and environmental water sample. It was found that the extraction efficiency (E%) and the enrichment factor (F) of SDZ and SMT were influenced by the types of salts, the concentration of salt, the concentration of POELE10 and the temperature. The orthogonal experimental design (OED) was adopted in the multi-factor experiment to determine the optimized conditions. The final optimal condition was as following: the concentration of POELE10 is 0.027gmL(-1), the concentration of Na2C4H4O6 is 0.180gmL(-1) and the temperature is 35°C. This POELE10-Na2C4H4O6 ATPS was applied to separate and enrich SDZ and SMT in real samples (i.e., water, egg and milk) under the optimal conditions, and it was found that the recovery of SDZ and SMT was 96.20-99.52% with RSD of 0.35-3.41%. The limit of detection (LOD) of this method for the SDZ and SMT in spiked samples was 2.52-3.64pgmL(-1), and the limit of quantitation (LOQ) of this method for the SDZ and SMT in spiked samples was 8.41-12.15pgmL(-1).

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Antibiotics such as sulfonamides and tetracyclines are frequently used in veterinary medicine. Due to incomplete absorption in the animal gut and/or unmetabolized excretion, the substances can enter the environment by using manure as soil fertilizer. The anaerobic fermentation process of biogas plants is discussed as potential sink for antibiotic compounds. However, negative impacts of antibiotics on the fermentation process are suspected. The elimination of sulfadiazine, sulfamethazine, tetracycline and chlortetracycline in semi-continuous lab-scale fermenters was investigated. Both biogas production and methane yield were not negatively affected by concentrations up to 38 mg per kg for sulfonamides and 7 mg per kg for tetracyclines. All substances were partly eliminated with elimination rates between 14% and 89%. Both matrix and structure of the target molecule influenced the elimination rate. Chlortetracycline was mainly transformed into iso-chlortetracycline. In all other cases, the elimination pathways remained undiscovered; however, sorption processes seem to have a negligible impact.

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Iminodiacetic acid (IDA) is dicarboxylic acid amine, which may produce stronger interaction with polar or charged compounds than bidentate α,ß-amino acid. In this article, a novel type of tridentate zwitterionic HILIC stationary phase was prepared by covalently bonding N-benzyl IDA on silica gel via copper(I) catalyzed Huisgen azide-alkyne 1,3-dipolar cycloaddition (CuAAC). The structure of this stationary phase and all related intermediates was confirmed by NMR, FT-IR, MS spectrum and elemental analysis. The new stationary phase showed good HILIC characteristics and high column efficiency (the theoretical plate number is up to 44000 plates m(-1) in the case of guanosine) in the application of separation of polar compounds, including organic acids, organic bases, as well as highly polar and hydrophilic compounds, such as cephalosporins and carbapenems. Most of them displayed good peak shape and selectivity.

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A highly selective sample cleanup procedure featuring molecularly imprinted solid-phase extraction (MISPE) was developed for the isolation and determination of sulfadiazine (SDZ) in seawater samples from Jiaozhou Bay, China. The molecularly imprinted polymer (MIP) was prepared using SDZ as the template molecule and methacrylic acid as the functional monomer. The MIP was used as a selective sorbent for the solid-phase extraction of SDZ. An off-line MISPE method followed by high-performance liquid chromatography (HPLC) with diode-array detection was established for the analysis of SDZ. Good linearity of the MISPE column for SDZ standard solutions was obtained within 0-200µgL(-1) (R(2)>0.99). The recoveries of spiked seawater samples were satisfactory as high as 88%. Finally, seven samples in Jiaozhou Bay were determined and there was no sulfadiazine found except #2 and #5 sample. The concentrations were respectively 0.33µgL(-1) and 0.28µgL(-1), and the relative standard deviations were 1.35% and 4.13% (n=3).

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A simple, convenient, and economic self-assembly miniaturized syringe assisted extraction (mini-SAE) using poly (hydroxyethyl methacrylate) polymer (PHEMA) as sorbent coupled with liquid chromatography was proposed for rapid screening of sulfadiazine (SD) and sulfamonomethoxine (SMM) in milk. The water-compatible PHEMA was synthesized by reversible addition-fragmentation chain transfer precipitation polymerization using trithiocarbonate as chain transfer agent and methanol-water system as reaction medium. The obtained PHEMA sorbent showed good affinity to sulfonamides and was successfully applied as a special sorbent for a mini-SAE device for simultaneous extraction and isolation of SD and SMM in milk samples. Under the optimum condition, good linearity was obtained in a range of 7.0-700 ng g(-1) (r≥0.9995) and the average recoveries of SD and SMM at three spiked levels were ranged from 85.6 to 100.3% with the relative standard deviations (RSD) ≤6.5%. The presented PHEMA-mini-SAE protocol could be potentially applied as an alternative tool for analyzing the residues of SAs in complicated biological samples.

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Paciente en tratamiento con sulfadiacina mas pirimetamina por toxoplasmosis oftálmica que desarrolla un cuadro de insuficiencia renal por depósito de cristales. Se observan al microscopio las imágenes características en gavilla de trigo de los cristales de sulfadiacina (AU)

A patient on treatment with sulfadiazine plus pyrimethamine for ophthalmic toxoplasmosis developed renal failure. Using a microscope it is possible to see the characteristic wheat sheaf images of the sulfadiazine crystals (AU)

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Veterinary antibiotics introduced into the environment may change the composition and functioning of soil microbial communities and promote the spreading of antibiotic resistance. Actual risks depend on the antibiotic's persistence and (bio)accessibility, which may differ between laboratory and field conditions. We examined the dissipation and sequestration of sulfadiazine (SDZ) and its main metabolites in soil under field conditions and how it was influenced by temperature, soil moisture, plant roots, and soil aggregation compared to controlled laboratory experiments. A sequential extraction accounted for easily extractable (CaCl2-extractable) and sequestered (microwave-extractable, residual) SDZ fractions. Dissipation from both fractions was largely temperature-dependent and could be well predicted from laboratory data recorded at different temperatures. Soil moisture additionally seemed to control sequestration, being accelerated in dry soil. Sequestration, as indicated by increasing apparent distribution coefficients and decreasing rates of kinetic release into CaCl2, governed the antibiotic's long-term fate in soil. Besides, we observed spatial gradients of antibiotic concentrations across soil aggregates and in the vicinity of roots. The former were short-lived and equilibrated due to aggregate reorganization, while dissipation of the easily extractable fraction was accelerated near roots throughout the growth period. There was little if any impact of the plants on residual SDZ concentrations.

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Recently, we reported on soil fate of SDZ residues amended with pig manure treated with ¹4C-labeled sulfadiazine ¹4C-SDZ). The first objective of the present study was to determine whether this strategy can be substituted by application of ¹4C-SDZ to soil. The second objective was to characterize non-extractable SDZ residues by fractionation, size exclusion chromatography (SEC) and solid state ¹³C-NMR. The fate of ¹4C-SDZ was examined for 28 d, using two soils with and without amendment of pig manure. Mineralization of ¹4C-SDZ was low; extractable residues decreased to 7-30%. Compared to the previous study, results were similar. ¹4C-SDZ derived bound radioactivity was found in HCl-washings, fulvic, humic acids and humin. According to SEC, one bound ¹4C portion (70%) co-eluted with fulvic acids (above 910 g mol⁻¹); the other consisted of adsorbed/entrapped ¹4C-SDZ. The ¹³C-SDZ study was performed for 30 d; humic acids were examined by ¹³C-NMR. A signal (100-150 ppm) was referred to ¹³C-SDZ. SEC and ¹³C-NMR demonstrated rapid integration of SDZ into humics.

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The worldwide use of veterinary antibiotics poses a continuous threat to the environment. There is, however, a lack of mechanistic studies on sorption and transformation processes for environmental assessment in soils. Two-week batch sorption experiments were performed with the antibiotic sulfadiazine (SDZ) in the plow layer and the subsoil of a loamy sand and a silty loam. The sorption and transformation parameters of SDZ and its main transformation products N1-2-(4-hydroxypyrimidinyl) benzenesulfanilamide (4-OH-SDZ) and 4-(2-iminopyrimidin-1(2H)-yl)aniline (An-SDZ) were estimated using a global optimization algorithm. A two-stage, one-rate sorption model combined with a first-order transformation model adequately described the batch data. Sorption of SDZ was nonlinear, time-dependent, and affected by pH, with a higher sorption capacity for the loamy sand. Transformation of SDZ into 4-OH-SDZ occurred only in the liquid phase, with half-life values of 1 month in the plow layers and 6 months in the subsoils. Under the exclusion of light, An-SDZ was formed in substantial amounts in the silty loam only, with liquid phase half-life values of 2 to 3 weeks. Despite the rather large parameter uncertainties, which may be reduced using additional information obtained from sequential solid phase extraction, the proposed method provides a framework to assess the fate of antibiotics in soils.

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In recent years, pharmaceutical and personal care products (PPCPs) have been detected in diverse environments (including groundwater, river water, and municipal wastewater). In order to evaluate their environmental impact, PPCPs must first be accurately determined. In this study, we focused on developing methods to accurately determine 10 sulfonamide antibiotics: sulfaguanidine, sulfacetamide, sulfadiazine, sulfathiazine, sulfapyridine, sulfamerazine, sulfamethazine, sulfamethoxazole, sulfadimethoxine, and sulfasalazine. While sulfonamides can easily be determined in pure water, wastewater influent and effluent collected from sewage treatment plants in Burlington and Toronto (Ontario) were found to generate confounding matrix effects. In an effort to overcome these matrix effects, we developed a solid phase microextraction (SPME) method to determine sulfonamides. Of the five different fiber assemblies investigated, the carbowax/divinylbenzene (CW/DVB) fiber produced the optimal response to sulfonamides. The SPME method was further optimized for sorption time (20min), solution salinity (10%, w/v, KCl), pH (4.5), and static desorption time (30min). When compared to solid phase extraction (SPE) using MCX cartridges, we observed that despite having higher MDLs and poorer sensitivity, SPME possessed the advantage of speed and reduced solvent usage. Most importantly, in contrast to SPE, when we applied the SPME method to fortified wastewater samples, we were generally able to accurately determine (i.e., recover) those sulfonamides that were present. Therefore, we conclude that SPME is a viable method for overcoming matrix effects in environmental samples.

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Four different techniques for the extraction of veterinary drugs were compared. The use of a high speed mixer/emulsifier, an ultrasonic bath, a Stomacher and an end-over-end mixer were used to extract both incurred and fortified residues of chlortetracycline, sulphadiazine and flumequine from chicken muscle. For each drug, similar analytical recoveries from fortified muscle samples were obtained using each of the extraction techniques. However, for each analyte the highest drug concentration detected in incurred samples was obtained following preparation using a mixer/emulsifier extraction. Residue concentrations obtained using sonication, Stomacher or end-over-end mixer procedures were as low as 20% of those obtained using the mixer/emulsifier. This highlights the need to measure both incurred and spiked samples during method validation. A survey of published methods indicated that 75% of laboratories use some form of high-speed homogenization for the extraction of drug residues from tissue. However only 52% reported detection of incurred residues. More than two-thirds of methods that used other forms of extraction did not measure incurred residues. The use of such methods has implications for the statutory detection of veterinary drug residues.

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The separation and determination of seven sulphonamides and trimethoprim by micellar electrokinetic capillary chromatography were successfully achieved, employing sodium dodecyl sulphate (SDS) as a micellar phase and tetrabutylammonium bromide as additive. The effects of surfactant and modifier concentrations, pH and applied voltage on the retention behaviour of the solutes and the column efficiency were studied. The migration time of sulponamides increase with increasing SDS concentration and decreasing the applied voltage, but varies only slightly with pH. There is an optimum applied voltage at which a higher theoretical plate number is achieved, in contrast to the sulphonamides, the retention behaviour of trimethoprim gave a more obvious response to changes in the experimental conditions. The determination of three active ingredients in tablets was performed using sulphathiazole as an internal standard with good results. The theoretical plate number ranged between 2.0 x 10(5) and 2.8 x 10(5) with a 50-cm capillary.

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A method for the isolation and liquid chromatographic determination of eight sulfonamides in milk is presented. Fortified or blank milk samples (0.5 ml) were blended with octadecylsilyl (C18T) derivatized silica (2 g). A column made from the sample C18T matrix was first washed with hexane (8 ml) following which the sulfonamides were eluted with methylene chloride (8 ml). The eluate contained sulfonamide analytes which were free from interferences when analyzed by high-performance liquid chromatography (HPLC) utilizing UV detection (270 nm, photodiode array). Standard curve correlation coefficients (range, 0.998 +/- 0.002 to 0.999 +/- 0.001), average percentage recoveries (73.1 +/- 7.4 to 93.7 +/- 2.7%), and the inter-(3.9-9.6%) and intra-assay (2.2-6.7%) variabilities, were determined for the concentration range examined (62.5-2000 ng/ml) and resulted in a minimal detectable limit of 1.25 ng on column (62.5 ng/ml, 20 microliters injection from a final sample volume of 0.5 ml). Savings in terms of time and solvent make this procedure attractive when compared to classical isolation techniques for sulfonamides.

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