Sulfathiazole Research Articles

Phototoxicity and oxidative stress responses in Daphnia magna under exposure to sulfathiazole and environmental level ultraviolet B irradiation

Sulfonamide antibiotics frequently occur in aquatic environments. In this study, phototoxicity of sulfathiazole (STZ) and its mechanism of action were investigated using Daphnia magna. We evaluated the changes of molecular level stress responses by assessing gene expression, enzyme induction and lipid peroxidation, and the related organism-level effects in D. magna. In the presence of ultraviolet B (UV-B) light (continuous irradiation with 13.8 ± 1.0 μW cm −2 d −1), STZ (at the nominal concentration of 94.9 mg/L) caused a significant increase in reactive oxygen species (ROS) generation and lipid peroxidation. Catalase (CAT) and glutathione S-transferase (GST) showed concentration-dependent increases caused by the exposure. Exposure to STZ and UV-B light caused apparent up-regulation of α- esterase, hemoglobin, and vitellogenin mRNA. The survival of daphnids was significantly affected by the co-exposure to STZ and UV-B. The biochemical and molecular level observations in combination with organism-level effects suggest that the phototoxicity of STZ was mediated in part by ROS generated by oxidative stress in D. magna.

Residues of antibiotics and sulfonamides in honeys from Basque Country (NE Spain)

AbstractBACKGROUND: The aim of this work was to ensure that Label Basque market honey is free of veterinary residues.RESULTS: A total of 567 Basque honey samples were previously analyzed with the respective Charm II system—68 samples were presumptive positive for sulfonamides (SA‐s), 24 samples for tetracyclines (TC‐s), and no positive samples for chloramphenicol (CAP) (<0.3 µg kg−1) residues. The residues were mostly confirmed by liquid chromatography fluorescence detection (LC‐FD) and tandem mass spectrometry (LC‐MS/MS), according to the latest European Union criteria for the analyses of veterinary drug residues (2002/657/EC). These techniques confirmed that 19 of the 68 samples, presumptive contaminated with SA‐s, contained sulfathiazole (STZ) residues at levels from 20 to 210 µg kg−1, and the 24 samples presumptive contaminated with TC‐s, were also confirmed, showing tetracycline (TC) levels from 15 to 920 µg kg−1. Linearity range, decision limit (CCα), detection capability (CCβ), precision and reproducibility were also determined.CONCLUSION: Residues of veterinary drugs were confirmed in a very limited number of honey samples: sulfathiazole (3.40%) and tetracycline (4.22%). This work reports the advantages of the Charm II assay, but also its limitations, detecting SA‐s in most (87.7%) of the heather (Erica vagans) honey samples. The false positives detected in this honey were assumed to be of an unknown compound that has not been confirmed as a drug residue. Until now, no studies have been performed to find out if other heather honeys of different geographical origins give similar false positives for SA‐s. Copyright © 2008 Society of Chemical Industry

Effects of Ionic Strength, Temperature, and pH on Degradation of Selected Antibiotics

Aqueous degradation rates, which include hydrolysis and epimerization, for chlortetracycline (CTC), oxytetracycline (OTC), tetracycline (TET), lincomycin (LNC), sulfachlorpyridazine (SCP), sulfadimethoxine (SDM), sulfathiazole (STZ), trimethoprim (TRM), and tylosin A (TYL) were studied as a function of ionic strength (0.0015, 0.050, or 0.084 mg/L as Na(2)HPO(4)), temperature (7, 22, and 35 degrees C), and pH (2, 5, 7, 9, and 11). Multiple linear regression revealed that ionic strength did not significantly affect (alpha = 0.05) degradation rates for all compounds, but temperature and pH affected rates for CTC, OTC, and TET significantly (alpha = 0.05). Degradation also was observed for TYL at pH 2 and 11. No significant degradation was observed for LNC, SCP, SDM, STZ, TRM, and TYL (pH 5, 7, and 9) under study conditions. Pseudo first-order rate constants, half-lives, and Arrhenius coefficients were calculated where appropriate. In general, hydrolysis rates for CTC, OTC, and TET increased as pH and temperature increased following Arrhenius relationships. Known degradation products were used to confirm that degradation had occurred, but these products were not quantified. Half-lives ranged from less than 6 h up to 9.7 wk for the tetracyclines and for TYL (pH 2 and 11), but no degradation of LIN, the sulfonamides, or TRM was observed during the study period. These results indicate that tetracyclines and TYL at pH 2 and 11 are prone to pH-mediated transformation and hydrolysis in some cases, but not the sulfonamides, LIN nor TRM are inclined to degrade under study conditions. This indicates that with the exception of CTC, OTC, and TET, pH-mediated reactions such as hydrolysis and epimerization are not likely removal mechanisms in surface water, anaerobic swine lagoons, wastewater, and ground water.

Use of Urea as Habit Modifier in the Supercritical Antisolvent Micronization of Sulfathiazole

The purpose of this work is to study the effect of urea as an additive for the habit modification of sulfathiazole (STZ) crystals formed using supercritical antisolvent (SAS) precipitation. The process was performed using acetone and carbon dioxide as solvent and antisolvent, respectively. The effect of STZ concentration, urea concentration, temperature, and pressure on the crystals habit was investigated, and the obtained products were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and differential scanning calorimetry (DSC). Urea was found to be very effective in the modification of the crystal habit and size of STZ crystals. The habit changed from a plate shape to spherical particles with a very narrow particle size distribution at a urea/STZ mass ratio of 1%. Mean particle size ranged between 0.5 and 1 μm depending on the STZ concentration in acetone. XRD and DSC analysis indicated the formation of a form I polymorph among the five known polymorphisms of STZ. Because of rapid precipitation, only partly crystalline particles were observed with respect to the raw material. Despite the use of urea as an additive, no detectable urea residue was found in the crystals, because urea is soluble in carbon dioxide and is effectively removed during the washing step with CO 2 . It is, thus, concluded that urea is mainly adsorbed on the crystal surface rather than being incorporated into the lattice of the STZ crystals.

Effects of Sorbate Speciation on Sorption of Selected Sulfonamides in Three Loamy Soils

Sorption of sulfamethazine (SMN) and sulfathiazole (STZ) was investigated in three soils, a North Carolina loamy sand, an Iowa sandy loam, and a Missouri loam, under various pH conditions. A significant increase in the sorption coefficient (KD) was observed in all three soils, as the sulfonamides converted from an anionic form at higher pH to a neutral/cationic form at lower pH. Above pH 7.5, sulfonamides exist primarily in anionic form and have higher aqueous solubility and no cationic character, thereby consequently leading to lower sorption to soils. The effect of speciation on sorption is not the same for all sulfonamides; it is a function of the pH of the soil and the pKa of the sulfonamides. The results indicate that, for the soils under investigation, SMN has comparatively lower KD values than STZ. The pH-dependent sorption of sulfonamides was observed to be consistent in all three soils investigated. The KD values for each speciated form-cationic, neutral, and anionic-were calculated using an empirical model in which the species-specific sorption coefficients (KD0, KD1, and KD2) were weighted with their respective fractions present at any given pH.

Trace determination of sulfonamides residues in meat with a combination of solid-phase microextraction and liquid chromatography–mass spectrometry

An integrated method of combining solid-phase microextraction (SPME) with liquid chromatography–mass spectrometry (LC–MS) was evaluated for determination trace amount of sulfonamides in meat products. Eight commonly used sulfonamides, sulfadiazine (SDZ), sulfathiazole (STZ), sulfamerazine (SMR), sulfamethazine (SMT), sulfamonomethoxine (SMMX), sulfamethoxazole (SMXZ), sulfaquinoxaline (SQX) and sulfadimethoxine (SDMX), were investigated in this study. Chromatography was performed on a C 18 reversed-phase column using an isocratic acetonitrile in water as the mobile phase. Fiber coated with a 65 μm thickness of polydimethylsiloxane/divinylbenzene (PDMS/DVB) was used to extract sulfonamides at optimum conditions. Analytes were desorbed with static desorption in an SPME-HPLC desorbed chamber for 15 min and then determined by LC–MS. The detection limits of these sulfonamides in pork were from 16 μg kg −1 (SMT) to 39 μg kg −1 (SMMX). According to the analysis, the linear range was from 50 to 2000 μg kg −1 with relative standard deviation (R.S.D.s) value below 15% (intra-day) and 19% (inter-day). The proposed method was tested by analyzing meats from a local market for sulfonamides residues. Some sulfonamides in our study were detected in the meat samples. The concentration of these residual sulfonamides ranged from 66 μg kg −1 (SDZ) to 157 μg kg −1 (SQX) in a chicken sample. The results demonstrate that the SPME–LC–MS system is highly effective in analyzing trace sulfonamides in meat products.

Simultaneous Determination of 17 Sulfonamides and the Potentiators Ormetoprim and Trimethoprim in Salmon Muscle by Liquid Chromatography with Tandem Mass Spectrometry Detection

A simple, robust method using liquid chromatography/tandem mass spectrometry (LC/MS/MS) for the simultaneous determination of 17 sulfonamides [sulfanilamide (SNL), sulfacetamide (SAA), sulfaguanidine (SGD), sulfapyridine (SPY), sulfadiazine (SDZ), sulfathiazole (STZ), sulfamerazine (SMR), sulfamethoxazole (SOZ), sulfamoxole (SXL), sulfisoxazole (SXZ), sulfamethizole (SML), sulfamethazine (SMZ), sulfamethoxypyridazine (SMP), sulfamonomethoxine (SMM), sulfachloropyridazine (SCP), sulfaquinoxaline (SQX), and sulfadimethoxine (SDM)] and 2 potentiators [ormetoprim (OMP) and trimethoprim (TMP)] in fish tissue has been developed. The analytes were extracted from homogenized fish tissue with water-acetonitrile (50 + 50). The extract was clarified by centrifugation and a portion defatted with hexane. The analytes were partitioned into chloroform and evaporated to dryness. The redissolved residue was applied to a C18 reversed-phase column with a water-acetonitrile (0.1% acetic acid) gradient. All of the compounds were completely separated and detected in <10 min at 30 degrees C using LC/MS/MS. Standard curves were linear over the range of 0.02 to 5 ng injected. The limit of detection varied from 0.1 ng/g for SMZ and OMP to 0.9 ng/g for SXL and SOZ. Recoveries varied from 100% for SDM, SOZ, and SQX and 85% for SMR, OMP, and TMP to approximately 30% for SAA. Relative standard deviations for repeat analysis varied from 4% for SMZ and SCP to 23% for SAA.

Sorption of the Veterinary Antimicrobial Sulfathiazole to Organic Materials of Different Origin

Sulfonamides (SA), ionizable, polar antimicrobial compounds, may reach the environment in substantial amounts by the spreading of manure. The environmental behavior of SA is still difficult to predict. We investigated the influence of the main factors supposed to control SA sorption to organic materials: composition of sorbent, solute chemistry, and contact time. For that purpose, sulfathiazole (STA) sorption to compost, manure, and humic acid after 1 and 14 d was studied under sterile conditions. The experiments demonstrated that sorption was most strongly affected by contact time and pH. Irrespective of sorbent and pH, sorption continued substantially after the fast initial sorption within 1 d. For all sorbents and both contact times, STA sorption exhibited a pronounced pH dependence. Species-specific Koc values decreased in the order KoccatiOn>> Kocneutral > Kocanion. Differences in sorbent composition influenced STA sorption weaker. Forthe neutral STA species, NMR chemical shift regions assignable to ketonic, carboxylic, and phenolic C as well as aromatic C-H and methoxyl/N-alkyl C seemed to control sorption. Forthe cations, sorption followed the cation exchange capacities of the sorbents. STA sorption to manure and humic acid increased with higher ionic strength (0.31 M compared to 0.06 M) at pH 7.5.

Determination of sulfonamide compounds in sewage and river by mixed hemimicelles solid-phase extraction prior to liquid chromatography–spectrophotometry

Mixed hemimicelles-based solid-phase extraction was investigated for the preconcentration of five sulfonamides from environmental water samples prior to HPLC–spectrophotometry determination in this paper. A comparative study on the use of sodium dodecyl sulfate (SDS) coating γ-alumina or octadecyltrimethylammonium bromide (OTMABr) and OTMABr coating silica as sorbent materials were presented. The five analytes (sulfadiazine (SDA), sulfathiazole (STA), sulfapyridine (SPD), sulfamethazine (SMZ) and sulfamethoxazole (SMX)) were quantitatively adsorbed on OTMABr-γ-alumina and OTMABr-silica mixed hemimicelles, but OTMABr-γ-alumina was not adopted because it worked at a high pH (around 10), instead, OTMABr-silica was selected to overcoming the pH restriction. The analytes retained on the cartridge were quantitatively desorbed with suitable amounts of methanol. Factors influencing the extraction efficiency, such as the amount of surfactant, pH of sample and breakthrough volume were discussed. The proposed method had been applied to determining the five sulfonamides in several environmental water samples and concentration factors of 300 and 600 for SDA and other four analytes were achieved, respectively. Detection limits obtained ranged between 0.15 and 0.35 μg/L for this five sulfonamides under the optimized conditions. The accuracy of the method was evaluated by recovery measurements on spiked samples, and good recovery results (89–113%) with precision of 3–6% were achieved.

Antibiotic Transport via Runoff and Soil Loss

Research has verified the occurrence of veterinary antibiotics in manure, agricultural fields, and surface water bodies, yet little research has evaluated antibiotic runoff from agricultural fields. The objective of this study was to evaluate the potential for agricultural runoff to contribute antibiotics to surface water bodies in a worst-case scenario. Our hypothesis was that there would be significant differences in antibiotic concentrations, partitioning of losses between runoff and sediment, and pseudo-partitioning coefficients (ratio of sediment concentration to runoff concentration) among antibiotics. An antibiotic solution including tetracycline (TC), chlortetracycline (CTC), sulfathiazole (STZ), sulfamethazine (SMZ), erythromycin (ERY), tylosin (TYL), and monensin (MNS) was sprayed on the soil surface 1 h before rainfall simulation (average intensity = 60 mm h(-1) for 1 h). Runoff samples were collected continuously and analyzed for aqueous and sediment antibiotic concentrations. MNS had the highest concentration in runoff, resulting in the highest absolute loss, although the amount of loss associated with sediment transport was <10%. ERY had the highest concentrations in sediment and had a relative loss associated with sediment >50%. TYL also had >50% relative loss associated with sediment, and its pseudo-partitioning coefficient (P-PC) was very high. The tetracyclines (TC and CTC) had very low aqueous concentrations and had the lowest absolute losses. If agricultural runoff is proven to result in development of resistance genes or toxicity to aquatic organisms, then erosion control practices could be used to reduce TC, ERY, and TYL losses leaving agricultural fields. Other methods will be needed to reduce transport of other antibiotics.

Multiwalled carbon nanotubes as sorbent for on-line coupling of solid-phase extraction to high-performance liquid chromatography for simultaneous determination of 10 sulfonamides in eggs and pork

The sulfonamides (SAs) have been widely used as effective chemotherapeutics and growth promoters in animals’ feeding, but their residues could be a potential danger to human health due to their carcinogenic potency and possible antibiotic resistance. Development of a simple and sensitive method for the determination of SAs residues in food of animal origin, therefore, is of great significance. An on-line solid-phase extraction (SPE) method using multiwalled carbon nanotubes as sorbent coupled with high-performance liquid chromatography (HPLC) for simultaneous determination of 10 sulfonamides (SAs) in eggs and pork was developed. The adsorptive potential of carbon nanotubes for solid-phase extraction of sulfonamides was investigated for the first time in the present paper. To on-line interface solid-phase extraction with HPLC, a conventional sample loop on the six-port injector valve of the HPLC was replaced by a preconcentration column packed with carbon nanotubes. The analytes in water solution were preconcentrated onto the preconcentration column and subsequently eluted with mobile phase of methanol–water (22:78). The developed on-line solid-phase extraction method for HPLC permitted the current HPLC separation and the next preconcentration proceeded in parallel, and thus allows one determination finished within 35 min. The RSD of 10 SAs for nine replicate measurements of a standard mixture of 1 μg l −1 were in the range of 2.5–7.8%. The method was applied to the determination of trace sulfadiazin (SDZ), sulfamerazine (SMR), sulfadimidine (SDMD), sulfathiazole (STZ), sulfamoxol (SMO), sulfamethizole (SMT), sulfamethoxypyridazine (SMP), sulfachlorpyridazine (SCP), sulfadoxin (SDX) and sulfisoxazole (SIA) in eggs and pork. The results indicated that the proposed method was simple, cost-effective and sensitive.

Simultaneous extraction and analysis of 11 tetracycline and sulfonamide antibiotics in influent and effluent domestic wastewater by solid-phase extraction and liquid chromatography-electrospray ionization tandem mass spectrometry

Wastewater treatment plants (WWTPs) in which antibiotic compounds are not totally eliminated are considered to be point sources of antibiotic contamination in surface and ground waters. Therefore, there is a need for sensitive and reliable analytical methods for measuring these compounds in WWTP water matrices. This paper describes a simultaneous method for the determination of six tetracyclines (TCs) (oxytetracycline (OTC), tetracycline (TC), demeclocycline (DMC), chlortetracycline (CTC), doxycycline (DXC), meclocycline (MCC)) and five sulfonamides (SAs) (sulfathiazole (STZ), sulfamethazine (SMT), sulfachloropyridazine (SCP), sulfamethoxazole (SMX) and sulfadimethoxine (SDM)) using solid-phase extraction followed by liquid chromatography-ion trap tandem mass spectrometry. The average recovery of 11 antibiotics for simultaneous extraction was 83.3 ± 12.6 and 89.8 ± 11.5% for six TCs, and 95.2 ± 11.4 and 97.7 ± 10.6% for five SAs in the influent and effluent water, respectively. Matrix effects were found to be significant when measuring TCs but not SAs. The accuracy and day-to-day variation of the method fell within an acceptable range of 15% absolute. Method detection limits in wastewater matrices were between 0.03 and 0.07 μg/L. For the investigated 11 antibiotic compounds TC, DMC, CTC, DXC, SMT, SMX and SDM were found in the influents with a concentration range of 0.05–1.09 μg/L. CTC, DXC and SMX were also detected in the effluents with a concentration range of 0.06–0.21 μg/L. These results were compared with those in WWTP effluents of Canada, Germany and Switzerland.

Confirmation of Sulfamethazine, Sulfathiazole, and Sulfadimethoxine Residues in Condensed Milk and Soft-Cheese Products by Liquid Chromatography/Tandem Mass Spectrometry

A liquid chromatography/tandem mass spectrometry method (LC/MS/MS) is described for the simultaneous detection of 3 sulfonamide drug residues at 1.25 ppb in condensed milk and soft-cheese products. The 3 sulfonamide drugs of interest are sulfathiazole (STZ), sulfamethazine (SMZ), and sulfadimethoxine (SDM). The method includes extraction of the product with phosphate buffer, centrifugation of the diluted product, and application of a portion of the extract onto a polymeric solid-phase extraction cartridge. The cartridge is washed with water, and the sulfonamides are eluted with methanol. After evaporation, the residue is dissolved in 0.1% formic acid solution, and the solution is filtered before analysis by LC/MS/MS. The LC/MS/MS program involved a series of time-scheduled selected-reaction monitoring transitions. The transitions of MH+ to the common product ions at m/z 156, 108, and 92 were monitored for each residue. In addition, SMZ and SDM had a fourth significant and unique product ion transition that could be measured. Validation was performed with control and fortified-control condensed bovine milk with 2.5, 5, and 10 ppb sulfonamides. This method was applied to imported flavored and unflavored condensed milk and cream cheese bars. The presence of STZ and SMZ residues was confirmed in 3 out of 6 products.

Determination of sulphathiazole and sulphanilamide by photochemically induced fluorescence and first-derivative fluorescence

This manuscript reports the usefulness of the determination of sulphathiazole (ST) using photochemically induced fluorescence (RTPF) and RTPF coupling with first derivative (D 1-RTPF), and the determination of sulphanilamide (SAN) by meaning first derivative of the emission spectrum. By irradiating 5 min, with intense UV radiation, sulphathiazole, in ethanol:water 20:80 (v/v) solutions at pH 4.5–5.0, show fluorescence emission at 342 nm ( λ ex = 251 nm). Under these conditions, a linear relation, fluorescence intensity–ST concentration, was found between 0.23 and 3.00 μg mL −1 of ST. The method was applied for determining ST in a pharmaceutical drug. ST was also determined in honey by using the D 1-RTPF signal, applying the standard addition method, and measuring at 324.8 nm. Under the same experimental conditions of pH and solvent, a fluorimetric method for determining SAN in presence of ST is proposed. Calibration graphs for SAN determination were established using the amplitude of the first derivative of the emission spectrum measured at 324.4 nm, as the analytical signal. This method has been applied to determining SAN in a pharmaceutical formulation.

Strategies for solving matrix effects in the analysis of sulfathiazole in honey samples using three-way photochemically induced fluorescence data

A widely employed compound for honey treatment, sulfathiazole (ST), was determined in commercial honey samples, employing a combination of photochemically induced fluorescence excitation–emission matrices (EEMs) and chemometric processing of the recorded second-order data. Parallel Factor Analysis (PARAFAC) and Self-Weighted Alternating Trilinear Decomposition (SWATLD) methods were used for calibration. An appropriately designed calibration with a set of standards composed of 18 samples, coupled to the use of the second-order advantage offered by the applied chemometric techniques, allowed quantitation of sulfathiazole in spiked commercial honey samples. No previous separation or sample pretreatment steps were required. The results were compared with other calibration methods such as N-PLS and PLS-1 that produced good results on synthetic samples but not on the investigated commercial honey samples.

Routine monitoring of antibiotics in water and wastewater with a radioimmunoassay technique

Antibiotics are one of a group of pharmaceutical compounds that have been found in lakes and streams throughout the world and the occurrence of these compounds in the environment has raised concerns regarding the toxicity to aquatic organisms and the emergence of strains of antibiotic-resistant bacteria. The objective of this study was to assess the use of a relatively simple coupled solid-phase extraction (SPE)/radioimmunoassay (RIA) method for screening and/or monitoring tetracycline (TC) and sulfonamide (SA) compounds in water. Cross-reactivity of TCs and SAs was used to determine the specificity of the assays. The results indicate that TC, oxytetracycline (OTC), chlortetracycline (CTC) of the investigated 5 TCs, and sulfamethazine (SMT), sulfamethoxazole (SMX), sulfadimethoxane (SDM) and sulfathiazole (STZ) of the investigated 6 SAs in water matrix cross-react to a similar degree within each family in RIA and SPE/RIA. Water samples were collected across a watershed in northern Colorado in addition to the influent and effluent of a wastewater treatment plant. SPE/RIA analysis of these samples was compared with SPE/liquid chromatography (LC)-mass spectrometry (MS) quantification of 5 TC and 6 SA compounds. Results of the study indicate that SPE/RIA can be an effective technique for monitoring antibiotic compounds in waters suspected to be contaminated with these compounds. The coupled method provides a sufficiently low detection limit (0.05 μg/L) to screen large sample sets at environmentally relevant concentrations. The method provides a semi-quantitative composite measurement of similar compounds in an antibiotic family without complex and expensive analytical equipment.

Synthesis of fluoroalkyl end‐capped preoligomers containing succinimidyl segments—Application to novel fluorinated oligomers possessing surface antibacterial activity

AbstractFluoroalkyl end‐capped N‐acryloxysuccinimide (ASuI) cooligomers were prepared under very mild conditions by the cooligomerizations of fluoroalkanoyl peroxides with ASuI and comonomers such as N,N‐dimethylacrylamide (DMAA) and acryloylmorpholine (ACMO). These fluorinated ASuI cooligomers thus obtained were in general easily soluble in water and common organic solvents. These fluorinated ASuI cooligomers were also able to reduce the surface tension of water quite effectively to around 20 mN/m with a clear break point resembling a critical micelle concentration (CMC), although the corresponding nonfluorinated ASuI cooligomers were not effective for reducing the surface tension of water. Fluorinated ASuI cooligomers were applicable to new fluorinated precooligomers, and these precooligomers could react with several amino compounds such as aniline, cytosine, and cyclohexylamine to afford fluorinated cooligomer‐bound aromatic and cyclohexyl segments under mild conditions. Of particular interest, these fluorinated precooligomers were able to react with low molecular weight biocides such as sulfathiazole (STZ) and 3‐amino‐5‐hydroxypyrazole (AHP) to give the corresponding fluorinated cooligomers containing antibacterial segments under similar conditions. These cooligomers were shown to have not only a good oleophobicity imparted by fluorine but also surface antibacterial activity against Staphylococcus aureus. Therefore, our present fluorinated cooligomers containing antibacterial segments are suggested to have high potential for new fluorinated functional materials through their surface active property and surface antibacterial activity. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3874–3880, 2004

Determination of Sulfathiazole in Type C Medicated Swine Feed by Reversed-Phase Liquid Chromatography with Post-Column Derivatization

A convenient method was developed for determination of sulfathiazole (STZ) in Type C medicated swine feed by reversed-phase liquid chromatography (LC) with post-column derivatization. Addition of extractant solution (0.2N HCl and 1.5% diethylamine in 25% methanol) and an internal standard (IS), sulfamethylthiazole (SMZ), to 5 g sample was followed by mechanical shaking for 1 h. The extract was clarified by chilling, centrifugation, and filtering before injection onto a C18 reversed-phase column. The mobile phase components were 2% acetic acid and 1:1 acetonitrile-methanol (83 + 17%, v/v). Run time was about 20 min. Determination and, largely, the method's selectivity were based on detection at 450 nm of the derivative formed by the post-column reaction of dimethylaminobenzaldehyde with the primary amine of the analyte and IS. The IS, SMZ, differs from STZ by a single substituent methyl group, is stable, and is readily resolved from STZ. Although SMZ is not commercially available, it can be synthesized with relative ease from purchased reagents and will be supplied by the authors to interested laboratories. In single-laboratory validation, linearity was demonstrated over the range of 0.055-550 microg/mL, well beyond the target concentration of 5.5 microg/mL. The estimated limit of detection was 0.04 microg/mL; the calculated limit of quantitation was 0.13 microg/mL (feed concentration of 2.4 g/T or 2.7 mg/kg). Wet-spiking trials with a variety of swine feed matrixes showed recovery to be 100-102% for the intended concentration range, 50-200 g/T, with coefficient of variation (CV) < 2%. The method ruggedness was verified with an overall CV of 2.9%.

3-Aminophenol as a novel coupling agent for the spectrophotometric determination of sulfonamide derivatives

A rapid, simple and sensitive spectrophotometric method for the determination of some sulfa drugs is described. The method is based on the formation of orange yellow colored azo product by the diazotization of sulfonamides, viz., dapsone (DAP), sulfathiazole (SFT), sulfadiazine (SFD), sulfacetamide (SFA), sulfamethoxazole (SFMx), sulfamerazine (SFMr), sulfaguanidine (SFG) and sulfadimidine (SFDd) followed by a coupling reaction with 3-aminophenol in aqueous medium. Absorbance of the resulting orange yellow product is measured at 460 nm and is stable for 6 days at 27 °C. Beer's law is obeyed in the concentration range of 0.05–8.0 μg/ml at the wavelength of maximum absorption. The method is successfully employed for the determination of sulfonamides in various pharmaceutical preparations and common excipients used as additives in pharmaceuticals do not interfere in the proposed method. Plausible reaction mechanism is proposed for the formation of the azo product.

HPLC Determination of Sulfathiazole in French Honeys

A rapid reversed‐phase high‐performance liquid chromatographic method, with fluorimetric detection, is described for routine analysis of sulfathiazole (STZ) residues in honey. Samples were dissolved in 1 M hydrochloric acid and submitted to pre‐column derivatization with fluorescamine. Liquid chromatographic analysis of the fluorescent derivative is performed on a C18 column using a mobile phase of 2% acetic acid/ acetonitrile (60:40, v/v). The quantification limit obtained for STZ in honey was 10 µg/kg.