Linear sweep voltammetry (LSV) test parameters in alkaline medium were optimized by Doehlert matrix design in order to quantify the deleterious phases in a superduplex stainless steel UNS S32750. The microstructural analysis was performed, in several heat treated specimens, by Light Optical (LOM) and Scanning Electron (SEM) Microscopies and correlated with the electrochemical tests. In these tests, optimized parameters were obtained for tests in aqueous solutions of KOH. The concentration of 3.55 mol l −1 , scan rate of 3.42 mV s −1 and initial potential of −0.818 V, showed a good correlation between the deleterious phases precipitated and charge density values. Differently from LOM characterization, chi and sigma deleterious phases can be distinguished by LSV optimized test. Finally, this test can be a non-destructive powerful tool of quality control to detect embrittlement and corrosion resistance decay that commonly affected this stainless steel as consequence of inadequate fabrication processes.

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There are several chemicals for using as ultraviolet (UV) absorbers. Considering that titanium phosphate (TiP) not yet studied for this purpose, we intended to investigate its effect on poly(ethylene terephthalate) (PET). TiP was synthesized and intercalated with two types of long-chain amine, octadecylamine (OETiP) and ether-amine-O-(2-aminopropyl)-O′-(2-methoxyethyl)polypropylene glycol) (JETiP) being the intercalation assisted by ethylamine. Nanocomposites of PET/TiP (filled with 5 wt%) (PET-TiP, PET-OETiP, and PET-JETiP) were prepared by melting extrusion. Thermogravimetric analysis, differential scanning calorimetry, wide-angle X-ray diffraction (WAXD), Fourier transform infrared spectroscopy, hydrogen low-field nuclear magnetic resonance (1H LFNMR), and UV-visible (Vis) absorption were used for characterizations. OETiP and JETiP induced the decrease of PET glass transition temperature ( T g) and heat crystallization temperature ( T ch) while PET crystallinity degree ( X c), cold crystallization temperature ( T cc), and crystallization rate increased. WAXD suggested the intercalation of PET chains inside of fillers lamellae. According to 1H LFNMR, all fillers increased the PET molecular mobility. Diffuse reflectance revealed increase of the absorption at UV light region. The sample might be thought as a UV absorber.

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The synthesis and characterization of the reagent 2-(5-bromothiazolylazo)-4-chlorophenol and its application in the development of a preconcentration procedure for cobalt determination using flame atomic absorption spectrometry after cloud point extraction is presented. This procedure is based on cobalt complexing and entrapment of the metal chelates into micelles of a surfactant-rich phase of Triton X-114. The preconcentration procedure was optimized by using a response surface methodology through the application of the Box-Behnken matrix. Under optimum conditions, the procedure determined the presence of cobalt with an LOD of 2.8 μg/L and LOQ of 9.3 μg/L. The enrichment factor obtained was 25. The precision was evaluated as the RSD, which was 5.5% for 10 μg/L cobalt and 6.9% for 30 μg/L. The accuracy of the procedure was assessed by comparing the results with those found using inductively coupled plasma-optical emission spectrometry. After validation, the procedure was applied to the determination of cobalt in pharmaceutical preparation samples containing cobalamin (vitamin B12).

Sildenafil citrate and furosemide are two drugs very well-known and used. Sildenafil citrate is a drug widely used and effective in the current treatment of erectile dysfunction, but it is also efficient in the treatment of pulmonary hypertension. Furosemide is a drug class of loop diuretics, so classified by acting on the loop of Henle. It is illegally used by athletes for weight loss and at masking doping substances. The quantification of pharmaceuticals have raised great interest in various aspects, for quality control, surveillance, testing of doping among others. This work aims to evaluate the applicability of handmade carbon based composite electrodes-paraffin voltammetry determination of sildenafil citrate and furosemide quickly and with low cost. Different parameters were evaluated for the determination of the cited pharmaceuticals and analytical curves were obtained with linear behavior in the range studied. For sildenafil citrate, the limit of detection and quantification were of 9 µmol L -1 and 27 µmol L -1 , respectively. To furosemide, the limit of detection was 2.72 µmol L -1 and quantification 9.06 µmol L -1. The pH's electrochemical measurements were performed at pH 8.0 for sildenafil citrate and pH 5.3 for furosemide, with a peak of oxidation at +1.2 V and +1.1 V, respectively (vs Ag|AgCl). The recovery percentage verified for sildenafil citrate was 83 % and 81 % for two commercial samples. Moreover, the average recovery of the analyte, furosemide, in simulated synthetic urine samples was above 88 %. Keywords Viagra; voltammetry; sildenafil citrate; furosemide; composite electrodes. ResumoO citrato de sildenafil e a furosemida são dois fármacos muito conhecidos e utilizados. O citrato de sildenafil é um fármaco amplamente empregado e eficaz no tratamento atual da disfunção erétil, mas que também é eficiente no tratamento à hipertensão pulmonar arterial (HAP). A furosemida é um fármaco da classe dos diuréticos de alça, assim classificado por atuar na alça de Henle. É usado de maneira irregular por atletas para a perda de peso e no mascaramento de substâncias dopantes. A determinação de fármacos tornou-se fundamental para o controle de qualidade, fiscalização, testes de dopping entre outros. Este trabalho tem por objetivo avaliar a aplicabilidade do eletrodo compósito artesanal à base carbono-parafina na determinação voltamétrica do citrato de sildenafil e da furosemida de maneira rápida e com baixo custo. Foram avaliados diferentes parâmetros da técnica para a determinação dos fármacos citados, obtendo-se curvas analíticas com comportamento linear na faixa estudada. Para dois medicamentos comerciais do citrato de sildenafil, o limite de detecção e quantificação são de 9 µmol L -1 e 27 µmol L -1 , respectivamente. Já para a furosemida o limite de detecção foi de 2,72 µmol L -1 e de quantificação 9,06 µmol.L -1. As análises eletroquímicas foram realizadas em pH 8,0 para o citrato de sildenafil e de pH 5,3 para a furosemida, com pico de oxidação em +1,2 V e +1,1 V, respectivamente (vs Ag|A...