Study of the bioremediatory capacity of wild yeasts.

Microbial detoxification has been proposed as a new alternative for removing toxins and pollutants. In this study, the biodetoxification activities of yeasts against aflatoxin B1 and zinc were evaluated by HPLC and voltammetric techniques. The strains with the best activity were also subjected to complementary assays, namely biocontrol capability and heavy-metal resistance. The results indicate that the detoxification capability is toxin- and strain-dependent and is not directly related to cell growth. Therefore, we can assume that there are some other mechanisms involved in the process, which must be studied in the future. Only 33 of the 213 strains studied were capable of removing over 50% of aflatoxin B1, Rhodotrorula mucilaginosa being the best-performing species detected. As for zinc, there were 39 strains that eliminated over 50% of the heavy metal, with Diutina rugosa showing the best results. Complementary experiments were carried out on the strains with the best detoxification activity. Biocontrol tests against mycotoxigenic moulds showed that almost 50% of strains had an inhibitory effect on growth. Additionally, 53% of the strains grew in the presence of 100 mg/L of zinc. It has been proven that yeasts can be useful tools for biodetoxification, although further experiments must be carried out in order to ascertain the mechanisms involved.

Sublethal effects induced by captopril on Cyprinus carpio as determined by oxidative stress biomarkers.

To our knowledge, this is the first study to evaluate captopril-induced oxidative stress in fish, and specifically in the common carp Cyprinus carpio. At present, very few studies in the international literature evaluate the sublethal effects of captopril on aquatic organisms such as fish, and available ones focus on determination of median lethal concentration in crustaceans and algae. Also, studies evaluating these effects do not make reference to the mechanism of action of this pharmaceutical or its toxicokinetics. This limits our knowledge of the characterization of the sublethal effects of this medication and of its potential ecological impact. The present study aimed to evaluate the sublethal effects induced by three different concentrations of captopril, on C. carpio), by determination of activity of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx), as well as indicators of cellular oxidation: hydroperoxide content (HPC), lipid peroxidation (LPX) and protein carbonyl content (PCC). Specimens were exposed for 12, 24, 48, 72 and 96h to three different captopril concentrations: 1µgL-1, 1mgL-1 and 100mgL-1 (the first one has been detected environmentally, the other two have been associated with diverse toxic effects in aquatic species), and brain, gill, liver, kidney and blood samples were evaluated. Significant increases in HPC and LPX were observed mainly in kidney and gill, while PCC also increased in brain. Modifications were found in the activity of SOD (mostly in kidney, brain and blood), CAT (all organs) and GPx (kidney and gill). In conclusion, captopril induces oxidative stress in C. carpio.

Effect of amoxicillin exposure on brain, gill, liver, and kidney of common carp (Cyprinus carpio): The role of amoxicilloic acid.

Amoxicillin (AMX) is one of the most commonly prescribed antibiotics around the world due to its broad-spectrum activity against different bacterial strains as well as its use as a growth promoter in animal husbandry. Although residues of this antibacterial agent have been found in water bodies in diverse countries, there is not enough information on its potential toxicity to aquatic organisms such as the common carp Cyprinus carpio. This study aimed to evaluate AMX-induced oxidative stress in brain, gill, liver and kidney of C. carpio. Carp were exposed to three different concentrations of AMX (10 ng/L, 10 µg/L, 10 mg/L) for 12, 24, 48, 72, and 96 h, and the following biomarkers were evaluated: lipid peroxidation (LPX), hydroperoxide content (HPC), protein carbonyl content (PCC) and activity of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx). Amoxicillin and its main degradation product amoxicilloic acid (AMA) were determined by high performance liquid chromatography coupled with electrochemical detection and UV detection (HPLC-EC-UV). Significant increases in LPX, HPC, and PCC (P < 0.05) were found in all study organs, particularly kidney, as well as significant changes in antioxidant enzymes activity. Amoxicilloic acid in water is concluded to induce oxidative stress in C. carpio, this damage being highest in kidney. The biomarkers used are effective for the assessment of the environmental impact of this agent on aquatic species. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 1102-1120, 2017.

Screening and confirmatory methods for the analysis of macrocyclic lactone mycotoxins by CE with amperometric detection.

A simple analytical scheme for the screening and quantification of zearalenone and its metabolites, alpha-zearalenol and beta-zearalenol, is reported. Extracts from maize flour samples were collected by supercritical fluid extraction and afterwards, they were analyzed by CE with amperometric detection. This scheme allowed a rapid and reliable identification of contaminated flour samples according to the reference value established for zearalenone by directive 2005/38/EC (200 microg/kg). The sample screening method was carried out by CZE using 25 mM borate separation buffer at pH 9.2 and 25.0 kV as separation voltage, monitoring the amperometric signal at +700 mV with a carbon paste electrode. In this way, total amount of mycotoxins was determined and samples were processed in 4 min with a detection limit of 12 microg/L, enough to discriminate between positive (more than 200 microg/L total mycotoxins) and negative samples (less than 200 microg/L total mycotoxins). Positive samples were then subjected to CZE separation and quantification of each analyte was done with 50 mM borate running buffer modified with 30% methanol at pH 9.7 and 17.5 kV as separation voltage. Under these conditions, separation was achieved in 15 min with detection limits from 20 to 35 microg/L for each analyte.

Rapid quantitative analysis of letrozole, fluoxetine and their metabolites in biological and environmental samples by MEKC.

A micellar electrokinetic chromatographic method has been developed to analyze biological (human serum, saliva and urine) and environmental samples (three different water samples) for letrozole (LE), fluoxetine and their main metabolites. For this purpose a 20 mM borate buffer (pH 9.5) containing 20 mM SDS and 12% v:v 2-propanol was used as the background electrolyte. The samples were hydrodynamically injected for 6 s, separated in a fused-silica capillary at 25 kV and 50 degrees C and detected at 230 nm. Under these conditions, the migration times for all the studied compounds ranged from 3.0 up to 8.0 min. Linearity ranges were determined as 125-1500 ng/mL, whereas detection limits were from 37 to 120 ng/mL in biological samples and a value of 6 ng/mL in water samples. According to the validation study, the developed method was proved to be accurate, precise, sensitive, specific, rugged and robust. This method was applied to the analysis of different biological fluids at clinical levels, including two urine samples from patients undergoing treatment with LE or fluoxetine, and also to environmental samples at potentially polluting level. Prior to the determination, the samples were purified and pre-concentrated by means of an extraction-preconcentration step with a C18 cartridge and by eluting the compounds with methanol.

Micellar electrokinetic chromatographic screening of letrozole and its metabolite in human urine: validation and robustness/ruggedness evaluation.

A simple, rapid, and sensitive method has been proposed and validated to directly quantify letrozole (LE) and its metabolite, bis-4-cyanophenylmethanol (ME) in urine samples (without any additional treatment) by micellar electrokinetic capillary chromatography (MEKC). In an effort to improve the selectivity and sensitivity of the method, the chemical and instrumental parameters were optimized. The best conditions were: 70 mM borate buffer (pH 9.2) and 40 mM SDS as BGE, 25 kV and 20 degrees C as working voltage and temperature, respectively, with hydrodynamic injection for 6 s. The reliability of the proposed method was also proved by means of a validation procedure based on precision, accuracy, linearity, LOD (15 microg/L for both of them) and LOQ studies. Moreover, an innovatory experimental and statistical design approach, upon a Plackett-Burman fractional factorial model, which involves the simultaneous evaluation of the global robustness and ruggedness effects, was applied. As it has been already stated, the proposed method has been successfully used to directly quantify both compounds in human urine samples, without any additional treatment, but the previously reached LOD and LOQ values can be improved by applying an SPE preconcentration procedure, also developed and optimized by the authors in this work. Real determinations of these analytes in clinical urines of a patient under LE treatment were performed, too.

Analytical approaches to expanding the use of capillary electrophoresis in routine food analysis.

Capillary Electrophoresis (CE) is becoming an ever more powerful analytical technique for the separation, identification, and quantification of a wide variety of compounds of interest in many application fields. Particularly in food analysis this technique can offer interesting advantages over chromatographic techniques because of its greater simplicity and efficiency. Nevertheless, CE needs to advance with regard to compatibility with sample matrices, sensitivity, and robustness of the methodologies in order to gain even wider acceptance in food analysis laboratories, specially for routine work. This article presents various approaches to expanding the analytical usefulness of CE in food analysis, discussing their advantages over conventional CE. These approaches focus on sample screening, automated sample preparation with on-line CE arrangements, and the automatic integration of calibration in routine analytical work with CE.

Capillary electrophoretic determination of triamterene, methotrexate, and creatinine in human urine.

A capillary zone electrophoresis (CZE) method using a fused-silica capillary (60.2 cm x 75 microm ID) was investigated for the determination of triamterene (TRI), methotrexate (MTX), and creatinine (CREA) in human urine. The separation was performed using a hydrodynamic injection time of 7 s (0.5 psi), a voltage of 25 kV, a capillary temperature of 30 degrees C, and 40 mM phosphoric acid adjusted to pH 2.25 by addition of triethanolamine as separation electrolyte. Under these conditions, analysis takes about 15 min. A linear response over the 0.5-15.0 mg L(-1) concentration range was found for TRI and MTX, and 0.5-80.0 mg L(-1) for CREA. Dilution of the sample (water:urine, 1:1 for TRI and MTX, and 1:25 for CREA determination) was the only step necessary prior to analysis by electrophoresis. The developed method is easy, rapid, and sensitive and has been applied to determine triamterene,methotrexate, and creatinine in urine samples with satisfactory results.

Development of a capillary zone electrophoretic method to determine six antidepressants in their pharmaceutical preparations. Experimental design for evaluating the ruggedness of method.

A capillary zone electrophoresis method is proposed for the separation of six of the antidepressants most used for the treatment of mental illness (clomipramine, paroxetine, fluoxetine, citalopram, fluvoxamine, and trazodone). Optimum conditions for their separation were investigated. A background electrolyte solution consisting of 50 mM phosphate buffer adjusted to pH 2.0, hydrodynamic injection, and 25 kV as separation voltage were used. Relative standard deviations (RSD) were <0.38% and <2.93% for migration time and corrected peak area (n = 24), respectively. Detection limits obtained for the six antidepressants ranged from 0.03 to 0.11 mg L(-1). Stability of the solutions, linear concentration range, accuracy, and precision were examined during validation of the method. A ruggedness test of this method was performed using the fractional factorial model of Plackett-Burman, requiring in our case design of a matrix of 15 experiments, in which the influence of seven factors at three different levels was tested on different electrophoretic results: efficiency; resolution; and corrected peak area. Statistical evaluation of electrophoretic results was achieved by Youden and Steiner's method. The described method is rapid, sensitive, and rugged and it was tested for the pharmaceutical formulation analysis, giving recoveries between 95.6 and 99.1% with respect to the nominal content.

Development and validation method for determination of Paroxetine and its metabolites by nonaqueous capillary electrophoresis in human urine. Experimental design for evaluating the ruggedness of the method.

A simple, rapid, and sensitive procedure using nonaqueous capillary electrophoresis (NACE) to measure Paroxetine (one of the mostly used antidepressants for mental diseases treatment) and three metabolites has been developed and validated. Optimum separation of paroxetine and metabolites was obtained on a 57 cm x 75 microm capillary using a nonaqueous buffer system of 9:1 methanol-acetonitrile containing 25 mM ammonium acetate and 1% acetic acid, with temperature and voltage of 25 degrees C and 15 kV, respectively, and hydrodynamic injection. Fluoxetine was used as an internal standard. Good results were obtained for different aspects including stability of the solutions, linearity, accuracy, and precision. Detection limits between 9.3 and 23.1 microg.L(-1) were obtained for paroxetine and its metabolites. A ruggedness test of the method was carried out using the Plackett-Burman fractional factorial model with a matrix of 15 experiments. This method has been used to determine paroxetine and its main metabolite B at clinically relevant levels in human urine. Prior to NACE determination, the samples were purified and enriched by means of an extraction-preconcentration step with a preconditioned C18 cartridge and eluting the compounds with methanol.