RESUMO
We modified and evaluated the performance of a CuO/Cu electrochemical electrode for chemical oxygen demand (COD) determination by covering it with a Nafion (Nf) film. The resulting modified CuONf/Cu electrode sensor was used for the electrochemical determination of COD in river, slaughterhouse and estuarine water samples in order to evaluate its performance for this particular task. It was compared with the CuO/Cu sensor with no Nafion. The main electrochemical characteristics of interest, resistance, sensitivity, accuracy and reproducibility, were assessed by means of Linear Sweep Voltammetry using glucose as a standard. Results of these essays indicate that the procedure used produced smooth and firmly attached Nf films covering the whole copper surface. This sensor was shown to be resistant to interferences and effective in electro-oxidation of a wide range of organic compounds and therefore very useful for COD determination. Using the newly developed CuONf/Cu electrode an analytical linear range of 50 to 1000 mg·L-1 COD, with a detection limit of 2.11 mg·L-1 (n = 6) COD was achieved. The comparison shows that the CuONf/Cu sensor is more appropriate for COD determination than its counterpart with no Nafion.
RESUMO
OBJECTIVE: to analyze the clinical characteristics of gout patients with < 3 attacks and ≥ 3 acute attacks per year. METHODS: retrospective observational study carried out at 6-primary care (AP) and 2 hospitals. We included patient's ≥ 18 years during the years 2003-2007 inclusive. The study groups were: patients with 1-2 and ≥ 3 attacks/acute recurrences.The main variables: demographic, metabolic syndrome (MS), clinical features and treatment. STATISTICAL ANALYSIS: logistic regression model, p < 0.05. RESULTS: 3,130 patients were included. The mean age was 55.8 years and 81.1% were male:31.6% have ≥ 3 attacks per year. The prevalence of MS was 28.8% (CI: 27.2-30.4%) in patients with 1-2 attacks. Subjects with ≥ 3 acute attacks were associated with: MS (OR: 6.2; CI: 4.6-8.3; 65.8 vs. 11.8%), obesity (OR: 2.1; CI: 1.7-2.5;63.5 vs. 33.8%) and hypertension (OR: 1.6; CI: 1.3-1.9; 58.3 vs. 36.9%), p < 0.001; 58.4% continued to take allopurinol(50.3 vs. 62.2%; p < 0.001). CONCLUSIONS: patients with ≥ 3 attacks per year have a more severe disease with acute poly-articular, tophi and higher number of co-morbidities. It is important to control uric acid to reduce the recurrence of attacks in these patients.