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  • Author or Editor: Marija Kaštelan-Macan x
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Authors: Sandra Babić, Alka Horvat and Marija Kaštelan-Macan

A method for optimization of a TLC separation based on use of a genetic algorithm is described. The procedure was tested by optimization of the reversed-phase HPTLC separation of a mixture of six pesticides and satisfactory optimum results were obtained. The performance of the genetic algorithm was tested by measurement of the number of generations, the population size, the mutation probability, and the crossover probability. Three separation criteria ( MRF , R * and R **) were examined as fitness functions. The genetic algorithm was compared with the simplex method.

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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. Computer-assisted 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.

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Authors: Danijela Ašperger, Lidija Ćurković, Alka Horvat and Marija Kaštelan-Macan

Qualitative identification of Cu, Sn, Pb, Ni, and Fe in Cu-alloys is presented. The method involves anodic sampling of alloys, separation and identification by thin-layer chromatography (TLC). The powerful desktop-computer tool makes it easy to optimize ternary solvent mixtures. Optimization was performed graphically by means of R si≥1 as a selected separation criterion. Mobile phase composition for optimal separation was determined as MeOH−HCl−H2O (60:35:5, v/v). The method was applied to Persian helmet as real sample.

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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 H 2 C 2 O 4 -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.

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Authors: Sandra Babić, Alka Horvat, Dragana Mutavdžić, Dalibor Čavić and Marija Kaštelan-Macan

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.

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Authors: Sandra Babić, Danijela Ašperger, Dragana Mutavdžić, Alka Horvat and Marija Kaštelan-Macan

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 F 254 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.

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Authors: Danijela Ašperger, Dragana Mutavdžić, Sandra Babić, Alka Horvat and Marija Kaštelan-Macan

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 F 254 s plates with H 2 C 2 O 4 -methanol as mobile phase. Spots were detected and quantified at λ = 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.

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