Metodologias empregando sistemas de analise por injeção em fluxo para determinação de especies quimicas em materiais de revelancia individual

AUTOR(ES)
DATA DE PUBLICAÇÃO

1995

RESUMO

MethodoIogies employing flow injection system were presented for detemination of chemical species in materiaIs of industrial relevante. Initially, a tubular periodate seIective electrode was proposed and used for determination of glycerol in soaps and similar. The methodoIogy refers to the glicerol oxidation by periodate with potentiometric evaluation of this consume. Latter on, tlow based methodologies with enzymes immobilized were proposed with glycerol dehydrogenase for determination of glycerol (in wines) and glucose oxidase, for glucose/sucrose determination (in sugar cane juice). To improve sensitivity and stability, several parameters were investigated such as samples injected volumes, dimension of the reactors, carrier- to-confluent flow fatias, available time for oxidation, pH values and others. The glyceroI determination in soaps and similar employing a tubular periodate selective electrode was realized in the interval of concentration of o to 5000mg/l of glycerol. Statistics evaluation found E9mV)= -6,91+ 0,07[glycerol] with correlation coefficient as 0,9996 and reIative standard deviation (r .s.d.) of 0,5% (N = 11, for standard solution of 2000 mg/l of glycerol). The study of analyticals dados by method of least squares indicated a high correlation between the results associated to the proposed and reference methods - iodometric titration (0,8999). The determination of glycerol in wine samples based on the glycerol dehydrogenase reaction was conduzed in the interval of concentration of 0 to 15 mg/l of glycerol. Statistics evaluation found I (fl.) = 0,71 + 2,75[glycerol] with correlation coefficient as 0,9988 and r.s.d. of 0,92% (N = 11, for standard-solution of 6,0 mg/l of glycerol). The correlation between the results associated to the proposed method and the reference (high performance liquid chromatography) was 0,9970. The amperometric determination of glucose and/or sucrose (after acid hidrolysis) based on the glucose oxidase enzymatic reaction was conduzed in the interval of concentration of 0,0 - 0,6 and 0,0 - 8,0 mmol/l in glucose and sucrose respectivally. Statistics evaluation found the functions: I (nA) = -0,68 + 31,6[glucose] with r = 0,9992 and r.s.d. of 1,2% (N = 11, for standard-solution of 0,4 mmol/l in glucose); I (mA) = 0,0002 + 0,02[sucrose] - 0,0007[sucrose] with r = 0,9998 and r.s.d. of 1,5% (N = 11, for standard-solution of 8,0 mmol/lin sucrose). The correlations related between the results associated to the proposed and reference methods (chromatography/dionex) were 0,9888 (glicose) and 0,8978 (sucrose). The proposed systems process about 40 samples ver hour, yielding precise results (r .s.d. about 1 %) and in agreement with conventional methods. The proposals presented are simple in conception and application, and as temperature control is not required (for glycerol/ periodate, glucose and sucrose) they become particularly attractive for large scale analysis.

ASSUNTO(S)

materiais - analise materiais compostos materiais - propriedades magneticas

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