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A method was developed for the identification and quantification of oxytetracycline residues present in salmon muscle and skin using UV-Vis derivative spectrophotometry. With this method, it was possible to reduce the number of steps in the procedure typically required for instrumental analysis of a sample. The spectral variables, order of the derivative, scale factor, smoothing factor, and analytical wavelength were optimized using standard solutions of oxytetracycline dissolved in 900 mg/L oxalic acid in methanol. The matrix effect was significant; therefore, quantification for oxytetracycline residues was carried out using drug-free salmon muscle and skin samples fortified with oxytetracycline. The LOD and LOQ were found to be 271 and 903 μg/kg, respectively. The precision and accuracy of the method were validated using drug-free salmon muscle and skin tissues fortified at three different concentrations (8, 16, and 32 mg/kg) on 3 different days. The recoveries at all fortified concentrations were between 90 and 105%, and RSDs in all cases were less than 6.5%. This method can be used to screen out compliant samples and thereby reduce the number of suspect positive samples that will require further confirmatory analysis. [ABSTRACT FROM AUTHOR]

A new method for the determination and extraction of ethinyl estradiol and etonogestrel was developed for a pharmaceutical product consisting of a solid copolymer intrauterine ring for subsequent simultaneous quantification by ultraviolet-visible derivative spectrophotometry. The spectral variables were optimized for first derivative spectrophotometry with a smoothing factor of 4000 and an amplification factor of 10,000. A wavelength of 291.5 nm was selected for the determination of ethinyl estradiol by a graphical method, while for etonogestrel, zero-crossing was used at 249.5 nm. The limits of detection and quantification for ethinyl estradiol were 9.5 × 10−7and 9.0 × 10−6 mol/L and 1.1 × 10−6and 3.2 × 10−6 mol/L for etonogestrel, respectively. For the extraction method, the variables affecting the analytical signal were the extraction solvent, temperature, and extraction time; optimized conditions were 180 min at 76 ± 2°C in acetonitrile. The method was applied successfully for the first time to analyze intrauterine contraceptive rings. The sample contained 11.7 mg etonogestrel and 2.7 mg ethinyl estradiol; the recoveries were 93.6 ± 1.1% etonogestrel and 97.9 ± 1.5% ethinyl estradiol relative to the nominal concentration. The importance of this method involves its implementation in pharmaceutical laboratories. [ABSTRACT FROM PUBLISHER]

Abstract: In this work, a characterization of reagent chromophere 5-(4-sulphophenylazo)-8-aminoquinoline [SPA] by IR and 1H RMN was carried out and a pK a value of 3.55±0.03 was found as well. An 1:2 stoichiometry for the Cu(II)-SPA complex was determined at pH 9 by Job and molar ratio methods. A value of 1.4×1014 for the stability constant was also found. Based on the formation of this complex a new method for the copper determination in presence of gold and silver was developed by derivative spectrophotometry using a previous preconcentration on solid phase. In this method, the analytical measures were executed directly in the solid phase containing the complex. The Cu(II) reacts with the reagent chromophere SPA previously retained in the anionic exchange DEAE Sephadex A25. In this determination, the first derivative at 605nm was used. The quantification range was between (3.2±0.3×10−1)×10−8 and (94.4±0.9)×10−8 molL−1 (3.2±0.3×10−1)×10−8 , and (94.4±0.9)×10−8 molL−1. The repeatability expressed as RSD was between 1.1 and 2.0%. The method was applied successfully for the copper determination in mineral residuals and natural water samples. The results were consistent with those provided by ICP-mass spectrometry. [Copyright &y& Elsevier]

The article reports on the results of a study of copper and silver on SP Sephadex C25 as complexes with 1-phenyl-1,2-propanedione-2-oximethiosemicarbazone by derivative spectrophotometry. A description of the experimental set-up and measurement method is presented. The results of the study were consistent with those provided by inductively coupled plasma/mass spectrometry.

Abstract: A new method for the simultaneous determination of copper and gold was developed by derivative spectrophotometry using a previous preconcentration on solid phase. The method is based on the formation of Cu(II)-PPDOT and Au(III)-PPDOT complexes that are extracted from aqueous solution in only 20min on cationic exchange SP Sephadex C25. In this simultaneous determination, the second derivative and the zero crossing method were used. The copper and gold determinations were carried out at 278.0nm and 282.0nm, respectively. The determination range for both analytes was 1.6×10−8–141×10−8 molL−1. Good levels of repeatability (RSD) of 1.3% and 1.4% were observed for copper and gold, respectively. The method was applied successfully for the copper and gold determination in mineral residuals, minerals and natural water samples. The results were consistent with those provided by ICP-mass spectrometry. [Copyright &y& Elsevier]

Focuses on the development of a method for the sequential determination of attapulgite and nifuroxazide in pharmaceutical determinations by spectrophotometry. Studies of solvent, light and temperature effects; Requirement to obtain stable compounds for analytical purposes; Evaluation of the second-derivative spectra in the same samples.

This work presents a simple and fast method for the simultaneous determination of amiloride and furosemide by digital derivative spectrophotometry. HCl 1×10−2 mol/l dissolved in ethanol was used as solvent and to extract drugs from formulations. Subsequently the samples were evaluated directly by first digital derivative spectrophotometry, using a smoothing factor of 8 and scale factor of 1×10−4. The simultaneous determination of furosemide and amiloride can be carried out at 241.4 and 343.6 nm, respectively. In both cases, the zero crossing approach was used. When both compounds are present together in a sample, it is possible to quantify one in the presence of the other, without mutual interference. The determination range was found to be of 6.9×10−8 to 16×10−5 and 6.8×10−8 to 8×10−5 mol/l, for amiloride and furosemide, respectively. A good level of repeatability (RSD) of 0.9 and 0.6% was observed for amiloride and furosemide, respectively. The ingredients commonly found in commercial pharmaceutical formulations do not interfere. The proposed method was applied to the determination of these drugs in pharmaceutical formulations. [Copyright &y& Elsevier]

A new method for the simultaneous determination of iron and ruthenium at ultra-trace levels is proposed. The method is based on the formation of the iron and ruthenium complexes with 2,4,6-tri-(2-pyridil)-1,3,5-triazine (TPTZ) in the presence of hydroxylamine hydrochloride and buffer CH2ClCOOH/CH2ClCOONa (pH=3.0). The formation of the complexes and their retention on a cationic resin SP-Sephadex C25 were integrated in one step at 90 °C, with stirring for 90 min. Under these conditions a high preconcentration level was achieved for both analytes. The complexes retained on the solid phase were evaluated by second derivative spectrophotometry. The selected analytical wavelengths were 539.7 and 553.3 nm for the determination of ruthenium and iron, respectively, by using the zero crossing approach. The detection and quantification limits were 0.54 ng ml−1 and 1.79 ng ml−1 for ruthenium and 0.41 ng ml−1 and 1.38 ng ml−1 for iron. The proposed method was applied to the determination of both analytes in synthetic mixtures. [Copyright &y& Elsevier]

Abstract: The present study shows the formation and characterization of the ionic-pair between the antibiotic oxytetracycline and the dye crystal violet in ammonia solution pH 9.0±0.2 extracted into chloroform. The characterization was demonstrated using UV–vis spectrophotometry, 1H NMR, measurement of relaxation times T 1 and IR spectroscopy, using a comparison between the signals of individual pure compounds with the signals with the mixture CV–OTC in different alkaline media. The formation of ionic-pair was also corroborated by new signals and chemical shifts. (2D) NMR spectroscopy experiments show that the interaction is electrostatic. [Copyright &y& Elsevier]

Abstract: Chemical, electrochemical and flow variables were optimized to examine the effectiveness of the electrocoagulation process for the removal of copper, lead and cadmium. The electrochemical process, which uses electrodes of commercial laminate steel, was applied to simulated wastewater containing 12mgdm−3 of copper, 4mgdm−3 of lead and 4mgdm−3 of cadmium. The optimum conditions for the process were identified as pH=7, flow rate=6.3cm3 min−1 and a current density between 31 and 54Am−2. When the electrode geometric area and time of electrolysis reached critical values, the copper removal reached a maximum value of 80%. A linear relationship was identified between the current density and the mass of generated sludge. In addition, a linear relationship was found between specific energy consumption and current density. The results of this investigation provide important data for the development of an industrial-scale electrolytic reactor. [Copyright &y& Elsevier]

Abstract: A new method for the determination of FeTotal and Cu is proposed. The method is based on the formation of the iron and copper complexes with 5-sulfosalicylic acid (SSA), the optimal conditions were found, using SSA 5.1gL−1 in the presence of ammonia 7.5gL−1 (pH=10). Under these conditions the selected analytical wavelengths were 488.5 and 423.5nm for the determination of iron and copper, respectively, by using the zero crossing approach. The detection and quantification limits were 0.02mgL−1 and 0.07mgL−1 for iron and 1.14mgL−1 and 3.80mgL−1 for copper. The proposed method was applied to the determination of both analytes in pregnant liquid solutions and the recovery was between 98% and 100% and in all cases the relative standard deviation was minor to 2%. [Copyright &y& Elsevier]

A simple continuous flow method is proposed to eliminate copper interference in arsenic speciation by hydride generation, based on the selective retention of this interfering ion in an iminodiacetate chelating resin previous to the hydride generation process. The arsines generated were cold trapped and measured by ICP/OES. The proposed method allows about 98% of the copper present in the samples to be removed. Minor co-retention of As(V) was observed as a result of electrostatic interaction between the arsenate anion and the nitrogen of the iminodiacetate group of the chelating resin Muromac A-1, the charge distribution of which is modified when copper is chelated. The species As(III), MMA and DMA were not retained in the microcolumn, probably because these species are mainly in the molecular form at the working pH value (4.5). In synthetic samples containing 50 µg l-1 of each arsenic species together with 100 mg l-1 copper, the recoveries obtained were: As(V) 97.6%, As(III) 100%, MMA 99.8%, and DMA 99.9%. The method was applied to arsenic speciation in river water samples containing high levels of copper. [ABSTRACT FROM AUTHOR]

Introduction: This is the case of a 15-year-old boy who had been socially isolated in his house for over 1 year. He had become increasingly agitated, but refused any help offered. Objectives: To establish the role of community treatment in adolescents with mental health problems. Methods: Summary of the interventions taken place during the treatment Results: Initially this young person refused any medical treatment, so we tried first supportive therapy and CBT. He dicho not obtain any benefits as he appeared experiencias paranoid ideation and thoughts of being persecuted in the streets. With support from the occupational therapist, the young person started to take care of his personal hygiene. Afterwards he started to take oral medication with partial response. We decided to switch to im treatment. In conjunction with CBT, the young person was gradually able to llaves the house. All the sessions during the first fewmonths took place at his family home. These visits were weekly or twice weekly. Once he left the house, he attended the grupos at the day hospital. After 18months, he was dischargedwithout medication and he is currently studying for a degree. Conclusions: Community treatment in adolescent with mental health problems is a better opción to establish good rapport and avoid stressful situations that could take place in an in-patient facilita. [ABSTRACT FROM AUTHOR]

Amorolfine (AOF) is a compound with fungicide activity based on the dual inhibition of growth of the fungal cell membrane, the biosynthesis and accumulation of sterols, and the reduction of ergosterol. In this work a sensitive kinetic and spectrophotometric method for the AOF quantitation based on the AOF oxidation by means of KMnO4 at 30 min (fixed time), pH alkaline, and ionic strength controlled was developed. Measurements of changes in absorbance at 610 nm were used as criterion of the oxidation progress. In order to maximize the sensitivity, different experimental reaction parameters were carefully studied via factorial screening and optimized by multivariate method. The linearity, intraday, and interday assay precision and accuracy were determined. The absorbance-concentration plot corresponding to tap water spiked samples was rectilinear, over the range of 7.56 × 10−6–3.22 × 10−5 mol L−1, with detection and quantitation limits of 2.49 × 10−6 mol L−1 and 7.56 × 10−6 mol L−1, respectively. The proposed method was successfully validated for the application of the determination of the drug in the spiked tap water samples and the percentage recoveries were 94.0–105.0%. The method is simple and does not require expensive instruments or complicated extraction steps of the reaction product. [ABSTRACT FROM AUTHOR]

Background and Purpose: PPARβ enhances insulin sensitivity in adipocytes and skeletal muscle cells, but its effects on insulin signalling in endothelial cells are not known. We analysed the effects of the PPARβ/δ (PPARβ) agonists, GW0742 and L165041, on impaired insulin signalling induced by high glucose in HUVECs and aortic and mesenteric arteries from diabetic rats. Experimental Approach: Insulin‐stimulated NO production, Akt‐Ser473 and eNOS‐Ser1177 phosphorylation, and reactive oxygen species (ROS) production were studied in HUVECs incubated in low‐ or high‐glucose medium. Insulin‐stimulated relaxations and protein phosphorylation in vessels from streptozotocin (STZ)‐induced diabetic rats were also analysed. Key Results: HUVECs incubated in high‐glucose medium showed a significant reduction in insulin‐stimulated production of NO. High glucose also reduced insulin‐induced Akt‐Ser473 and eNOS‐Ser1177 phosphorylation, increased IRS‐1‐Ser636 and ERK1/2‐Thr183‐Tyr185 phosphorylation and increased ROS production. The co‐incubation with the PPARβ agonists GW0742 or L165041 prevented all these effects induced by high glucose. In turn, the effects induced by the agonists were suppressed when HUVEC were also incubated with the PPARβ antagonist GSK0660, the pyruvate dehydrogenase kinase (PDK)4 inhibitor dichloroacetate or after knockdown of both PPARβ and PDK4 with siRNA. The ERK1/2 inhibitor PD98059, ROS scavenger catalase, inhibitor of complex II thenoyltrifluoroacetone or uncoupler of oxidative phosphorylation, carbonyl cyanide m‐chlorophenylhydrazone, also prevented glucose‐induced insulin resistance. In STZ diabetic rats, oral GW0742 also improved insulin signalling and the impaired NO‐mediated vascular relaxation. Conclusion and Implications: PPARβ activation in vitro and in vivo restores the endothelial function, preserving the insulin‐Akt‐eNOS pathway impaired by high glucose, at least in part, through PDK4 activation. [ABSTRACT FROM AUTHOR]

Abstract: The microextraction of crystal violet (CV) from water samples into polydimethylsiloxane (PDMS) using the rotating disk sorptive extraction (RDSE) technique was performed. The extracting device was a small Teflon disk that had an embedded miniature magnetic stirring bar and a PDMS (560μL) film attached to one side of the disk using double-sided tape. The extraction involves a preconcentration of CV into the PDMS, where the analyte is then directly quantified using solid phase spectrophotometry at 600nm. Different chemical and extraction device-related variables were studied to achieve the best sensitivity for the determination. The optimum extraction was performed at pH 14 because under this condition, CV is transformed to the neutral and colorless species carbinol, which can be quantitatively transferred to the PDMS phase. Although the colorless species is the chemical form extracted in the PDMS, an intense violet coloration appeared in the phase because the –OH bond in the carbinol molecule is weakened through the formation of hydrogen bonds with the oxygen atoms of the PDMS, allowing the resonance between the three benzene rings to compensate for the charge deficit on the central carbon atom of the molecule. The accuracy and precision of the method were evaluated in river water samples spiked with 10 and 30μgL−1 of CV, yielding a relative standard deviation of 6.2% and 8.4% and a recovery of 98.4% and 99.4%, respectively. The method detection limit was 1.8μgL−1 and the limit of quantification was 5.4μgL−1, which can be decreased if the sample volume is increased. [Copyright &y& Elsevier]

Abstract: This work forms part of an investigation which seeks to determine metal complexes in a solid phase by photoacoustic spectrometry (PAS). Results of spectral determination of Co(II) complexes are introduced. The method is based on Co(II) colorimetric reaction with 3-(2-pyridyl)-5,6-bis(4-sulfophenyl)-1,2,4-triazine (FST, ferrozine) retained on an anion-exchange resin, DEAE Sephadex A-25. The immobilization of Co(II) on the solid phase is combined with PAS measurement. A numerical approach is applied to reduce noise in the spectral data. At λ =477nm, the calibration for Co(II) is linear over the range 14–300 μgL −1. The Co(II) concentration in water samples was determined by conventional photoacoustic measurement. The relative standard deviation (R.S.D.) of the method for the calibration is <5%. Under optimized conditions, the obtained analytical features were LOD 14 μgL −1 and LOQ 45 μgL −1. [Copyright &y& Elsevier]