Qualidade de medicoes em quimica analitica. Estudo de caso: determinacao de cadmio por espectrofotometria de absorcao atomica com chama



Document title: Qualidade de medicoes em quimica analitica. Estudo de caso: determinacao de cadmio por espectrofotometria de absorcao atomica com chama
Journal: Quimica nova
Database: PERIÓDICA
System number: 000196309
ISSN: 0100-4042
Authors: 1

Institutions: 1Universidade de Sao Paulo, Instituto de Quimica, Sao Paulo. Brasil
2Instituto de Pesquisas Tecnologicas do Estado de Sao Paulo, Divisao de Quimica, Sao Paulo. Brasil
Year:
Season: May-Jun
Volumen: 24
Number: 3
Pages: 374-380
Country: Brasil
Language: Portugués
Document type: Artículo
Approach: Experimental
English abstract Calculation of uncertainty of results represents the new paradigm in the area of the quality of measurements in laboratories. The guidance on the Expression of Uncertainty in Measurement of the ISO / International Organization for Standardization assumes that the analyst is being asked to give a parameter that characterizes the range of the values that could reasonably be associated with the result of the measurement. In practice, the uncertainty of the analytical result may arise from many possible sources: sampling, sample preparation, matrix effects, equipments, standards and reference materials, among others. This paper suggests a procedure for calculation of uncertainties components of an analytical result due to sample preparation (uncertainty of weights and volumetric equipment) and instrument analytical signal (calibration uncertainty). A numerical example is carefully explained based on measurements obtained for cadmium determination by flame atomic absorption spectrophotometry. Results obtained for components of total uncertainty showed that the main contribution to the analytical result was the calibration procedure
Disciplines: Química
Keyword: Química analítica,
Cadmio,
Espectrofotometría,
Espectrofotometría de absorción atómica,
Incertidumbre,
Calibración,
Estandarización
Keyword: Chemistry,
Analytical chemistry,
Spectrophotometry,
Atomic absorption spectrophotometry,
Flame atomic absorption spectrophotometry,
Uncertainty,
Standarization,
Cadmium,
Calibration
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