Borges E. P., Vicente S., Grassi V., Ferreira M. M. C., Zagatto E. A. G.,  “A Simple Low-Injection System with Spectrophotometric Detection for Differential Kinetic Analysis”. Geelong, Victoria, Australia, 17-21/02/2003: 9th International Conference on Flow Analysis (Flow Analysis IX). Book of Abstracts, 145 (2003). Oral C27.

                                                                C27
 

    A SIMPLE FLOW-INJECTION SYSTEM WITH SPECTROPHOTOMETRIC
                    DETECTION FOR DIFFERENTIAL KINETIC ANALYSIS

Eduardo P. Borges, Simone Vicente, Viviane Grassi, Márcia M. C. Ferreira^* and Elias A. G.
                                                             Zagatto

           Centro de Energia Nuclear na Agricultura, Universidade de São Paulo, Brazil
                             Fax: +55 19 34294510 E-mail: ezagatto@cena.usp.br
 

A   single-line   flow-injection   system  is  designed  for   simultaneous   spectrophotometric
determination of copper  and nickel in alloys exploiting  differential  kinetics.  The strategy  is
supported by  the  pronounced  differences in rates  of  the reactions involving  the  analytes
and  a common complexing agent,  Br-PADAP  as  well  as  the absorbance additivity.  The
sample  is  injected   into  a  continuosuly   Br-PADAP   flowing  solution,   originating  two
coloured reactant zones that  coalesce as a consequence of sample dispersion.  Passage  of
the sample through  the detector  permits  then  successive  measurement  to  be  performed,
each one assciated  with a  different  yet reproducible  condition  for  reaction  development.
With this approach,  a number of  "pseudo-sensors"  is considered,  although only one single
wavelenght  spectrophotometer  is  concerned.  Data  are  treated by multivariate algorithms.
The proposed system is very simple and robust, processing 90 samples per hour that means
0.47 g Br-PADAP per determination. The first two principal components carry ca 93.2 and
clearly indicating the system dimensionality of  two.  Within  10 - 60 %  (w/w)  Ni  and  60 -
90  (w/w)  Cu,  results are precise  (r.s.d. < 2.0 and < 4.0 for Cu and Ni)  and in agreement
with  flame  atomic absorption.

                                                                                                 Support: FAPESP, CNPq