Dragana Mutavdžić

Solid Phase Extraction and HPLC Determination of Veterinary Pharmaceuticals in Wastewater

This work focuses on the application of SPE-HPLC analysis of important veterinary pharmaceuticals from different classes in highly complex wastewater matrix. The pharmaceutical investigated included three sulfonamides (sulfamethazine, sulfadiazine and sulfaguanidine), a sulfonamide synergist (trimethoprim), a tetracycline (oxytetracycline), a fluoroquinolone (enrofloxacine) and a beta-lactame (penicillin G/procaine). The method involves pre-concentration and clean-up by solid phase extraction (SPE) using Oasis HLB extraction catridges. Final analysis of the selected pharmaceutical compounds was carried out by high-performance liquid chromatography (HPLC) coupled with diode array detector (DAD). Recoveries were ranged from 68.3 to 97.9% with relative standard deviation below 8.4%. Only for sulfaguanidine low recovery was obtained. Limits of quantification were in the range 1.5-100mug/L depending on pharmaceutical. The described method was applied to the determination of pharmaceuticals in wastewater samples from pharmaceutical industry.

Comparison of Different Solid-Phase Extraction Materials for Sample Preparation in the Analysis of Veterinary Drugs in Water Samples

This paper focuses on the study of different types of SPE material that can be used for preconcentration of eight pharmaceuticals from water samples. The compounds studied were enrofloxacine, norfloxacine, Oxytetracycline, trimethoprim, sulfamethazine, sulfadiazine, sulfaguanidine, and penicillin G/procaine. Cartridges were tested on spiked water samples and extraction efficiency was determined by thin-layer chromatography (TLC) CN-modified chromatographic plates with 0.05 m H2C2O4-methanol, 81 + 19, as mobile phase. Strata-X cartridges were proved to be the best type of SPE material for this group of pharmaceutical compounds. For this reason an SPE—TLC method with Strata-X cartridges and HPTLC plates was validated. The method has been applied to the determination of pharmaceutical products in production wastewater samples from the pharmaceutical industry.

Solid-phase extraction and TLC quantification of enrofloxacin, oxytetracycline, and trimethoprim in wastewater

Quantitative determination of the antibiotics enrofloxacin, oxytetracycline, and trimethoprim in aquatic samples is reported. The method involves solid-phase extraction (SPE) and preconcentration of the antibiotics, separation by thin-layer chromatography (TLC) and quantification by video densitometry. TLC separation was performed on HPTLC CN F254s plates with H2C2O4-methanol as mobile phase. Spots were detected and quantified at X - 254 nm by videodensitometry. Limits of detection (LOD) and limits of quantification (LOQ) for TLC determination were calculated. The method was evaluated for spiked water samples. Antibiotics were extracted by solid-phase extraction (SPE) on a polystyrene-divinyl-benzene (SDB) Empore extraction disk. The extraction efficiency was checked by recovery experiments.

Determination of sulfonamides and trimethoprim in spiked water samples by solid-phase extraction and thin-layer chromatography

This paper describes a method for separation and quantification of a mixture of antibiotics extracted from spiked water samples. The method involves SPE of the analytes from water then analysis of the extract by TLC. Excellent separation of sulfadimidine, sulfadiazine, sulfaguanidine, and trimethoprim (TMP) was achieved by HPTLC on silica gel F254 plates with chloroform-methanol, 89 + 11, as mobile phase. Videodensitometric quantification was validated for linearity, precision, limit of detection, and limit of quantification. Limit of detection (LOD) was 0.05 µg per spot for sulfadimidine, sulfadiazine, and sulfaguanidine, and 0.1 µg per spot for TMP. Limit of quantification (LOQ) was 0.1 µg per spot for sulfadimidine, sulfadiazine, and sulfaguanidine, and 0.2 µg per spot for TMP. The TLC method was tested on extracts obtained, by use of solid-phase extraction, from spiked water samples. The best recovery of these antibiotics was achieved by use of HLB cartridges and elution with acetonitrile. Apparent recoveries were 87.1 ± 8.4 for sulfadiazine, 93.1 ± 6.4 for sulfadimidine, 16.1 ± 7.2 for sulfaguanidine, and 108.7 ± 23.7 for trimethoprim.

SPE preconcentration and TLC determination of alachlor, atrazine and α-cypermethrin in water samples

Quantitative determination of the pesticides alachlor, atrazine and α-cypermethrin in aquatic samples is reported. The method involves solid-phase extraction (SPE) for preconcentration of pesticides, separation of samples by means of thin-layer chromatography (TLC), and quantification by video densitometry. Computerassisted optimization was used to select the optimum mobile phase composition. The extraction procedure was optimized with regard to the type of elution solvent and the volume of sample.

Influence of Suspended Clay Minerals and Humic Matter on the Solid Phase Extraction Efficiency of Selected Pesticides from Water

The purpose of this investigation was to determine the influence of humic acids (HA) and Ca-montmorillonite (CaM) on the solid-phase extraction (SPE) efficiency of atrazine, alachlor and α-cypermethrin from water samples at various pH-values. The nature and intensity of binding of the studied pesticides to CaM were determined by X-ray diffraction analysis and termogravimetric analysis (TGA) test. The studied pesticides eluted from discs were analysed by thin-layer chromatography (TLC). The effects of CaM and humic acid were generally pH-dependent and acted independently in extraction efficiency influence. Lower recovery of pesticides was observed at higher pH values when CaM was ≥0.1 g and was attributed to greater dispersion of clay, increased surface area and subsequent adsorption. Concentrations of dissolved organic carbon (DOC) in humic acid had less effect on the extraction efficiency when water was at pH 8 compared to water at pH 2, which was probably due to greater nonpolar interactions of the pesticides to the charge-neutralized humic acid molecule.

Sample Preparation for TLC - Genetic Algorithm-Based Optimization of Microwave-Assisted Extraction

Optimization of microwave-assisted extraction (MAE) as a method of sample preparation in thin-layer chromatographic (TLC) analysis of a herbicide mixture is described. The extraction was optimized with regard to amount of solvent, duration of microwave extraction, and temperature. In the proposed method the experimental-design technique was used to design initial experiments and a genetic algorithm (GA) was used in the optimization procedure. The general objective was to test a mathematical tool which could facilitate optimization. The optimization procedure was tested in the TLC determination of a mixture of the herbicides atrazine and simazine; determination of recovery revealed results were satisfactory. The GA proved to be an optimization procedure which can be successfully applied to optimization of MAE experiments.