RESUMO
This work describes an electroanalytical investigation of dopamine using cyclic voltammetry (CV) and the graphite-polyurethane composite electrode (GPU). In CV studies, well-defined redox peaks characterize the oxidation process at the GPU electrode, which is indicative of electrocatalytic effects associated with active sites on the GPU electrode surface. A new analytical methodology was developed using the GPU electrode and square wave voltammetry (SWV) in BR buffer solution (0.1 mol L(-1); pH 7.4). Analytical curves were constructed under optimized conditions (f=60s(-1), DeltaE(a)=50 mV, DeltaE(I)=2 mV) and detection and quantification limits of 6.4x10(-8) mol L(-1) (12.1 microg L(-1)) and 5.2x10(-6) mol L(-1) (0.9 mg L(-1)), respectively, were achieved. The precision of the method was checked by performing ten successive measurements for a 9.9x10(-6) mol L(-1) dopamine solution. For intra-assay and inter-assay precisions, the relative standard deviations were 1.9 and 2.3%, respectively. In order to evaluate the developed methodology, the determination of dopamine was performed with good sensitivity and selectivity, without the interference of ascorbic acid in synthetic cerebrospinal fluid, which indicates that the new methodology enables reliable analysis of dopamine.
Assuntos
Dopamina/líquido cefalorraquidiano , Eletroquímica/métodos , Grafite/química , Poliuretanos/química , Eletrodos , Reprodutibilidade dos Testes , Sensibilidade e EspecificidadeRESUMO
A case of polyarteritis nodosa (PAN) in a 54 year-old man is presented. The clinical picture showed a 6-month history of mixed sensorimotor distal symmetrical polyneuropathy in all limbs together with anorexia, weight loss, fatigue, arthralgia, myalgia, mild fever and hypertension. The laboratory studies showed leucocytosis, elevated ESR, positive HBsAg and presence of cryoglobulins. Selective renal, celiac and mesenteric angiography was performed by femoral approach and has showed innumerable aneurysms most of them in hepatic and renal circulation. After about two weeks death has occurred. A brief discussion is done on clinical aspects of PAN pointing out the importance of HBsAg determination on etiopathogenesis and angiographic study on diagnosis.