Emprego de otimização multivariada no desenvolvimento de métodos para determinação de metais de interesse em soro e sangue integral humanos por espectrometria de absorção atômica em forno de grafite

Abstract

In this master's degree dissertation the developments of methods aredescribed for direct determination of V, Sb, Cr and Mn in human serum and Pb in human whole blood without need of previous digestion, using grafite furnace atomic absorption spectrometry technique. The serumsamples were diluted 1+4 with a solution of HNO3 1% v/v and Triton® X-100 0,1% v/v while the samples of blood were diluted 1+9 with a solution of HNO3 0,2% v/v and Triton® X-100 0,2% v/v. The optimization of the analysis parameters was accomplished through multivariate approach optimization, consisted of an experiment for variables selection (complete or fractional factorial design) followed by a methodology of surface answer (Central Composite Design (CCD) or Doehlertdesign). For all methods the best pyrolysis and atomization temperatures and the use of chemical modifiers, mainly permanent modifiers, were appraised. The matrix effect was evaluated in each method through the statistical tests F and t of Student, and, in some cases, the aqueous calibration became viable. The sensibility was analyzed through the characteristic masses and LODs. Studies of accuracy were madethrough recoveries of the metals in artificially polluted samples and, in the case of the lead in blood, certified materials were also used. The precision was determined in essaies made in a same day (precision intra-essay) and in different days (precision inter-essaies). Human serum and blood readings of voluntary individuals were also accomplished.