Bortoleto G. G., Verbi F. M., de Morais L., Onaga H., Ferreira M. M. C., Bueno M. I. M. S., "X- Ray Fluorescence and Multivariated Calibration for Determination of Metals". Córdoba, Argentina, 25-29/10/2004: IX Seminario Latinoamericano de Análisis por Técnicas de Rayos X (SARX 2004) [IX Latin American Seminary of Analysis by X-ray Techniques]. Avances en Análisis por Técnicas de Rayos X [Advances in Analysis by X-ray Techniques], 13 (2004) FRX27. Poster FRX27.

X-RAY FLUORESCENCE AND MULTIVARIATED CALIBRATION FOR
DETERMINATION OF METALS

Gisele G. Bortoleto*, Fabíola M. Verbi, Laís S. de Morais, Helena Onaga, Márcia M. C. Ferreira e Maria
Izabel M. S. Bueno

DQA – IQ – UNICAMP – C.P.: 6154 – CEP: 13083 970 Campinas, SP - Brazil * giseleb@iqm.unicamp.br
 

ABSTRACT
 

       X-ray  fluorescence  spectrometry  is  considered  a  well  established  analytical
method. Nevertheless research is still undergone to improve accuracy since the major
drawback in this technique  is  the  interelemental  interferences.  For  example,  it  is
uncommon to stablish a linear correlation between X-ray  characteristic  fluorescence
lines and the elemental concentrations in a natural sample. Other elements contributes
to the  signal  as  well.   For  many  years,   many  mathematical  methods  are  being
developed to solve this problem. However this “drawback” can be very well explored
   when chemometric tools are used. In this work, Partial Least Squares (PLS)  method
was employed to acquire a calibration model for  Cr,  Ni,  Zn,  Fe,  Cu,  Co  and  Pb
determination.   A  set standard water samples  with  known  concentrations  of these
elements was used.
        The  metals   in  aqueous  solutions   with  concentratios  around  mg  L^-1  were
measured in an EDXRF equipment (Spectrace 5000) and the  calibration  correlations
were obtained using  The Unscrambler 7.6  program.
       After  many  preprocessing  and  variable  selections   an   interesting  result  was
obtained  for  Pb  which  suffered  a  strong effect  of  the other elements.   The  best
calibration model obtained for this metal did not need the use of Pb lines (La and Lb),
but  instead  only  the  line  of   the  others  elements.   This  result  shows   the  great
contribution  the  multivariated  calibration  can  provide.   In the work  showed  here,
chemometric was able to consider all interelemental effects,  with more reliable results
than univariate analysis.
 

___________________________________________________________________________________________________
FRX27