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Previous issue date: 2014-11-03 === A ?gua produzida representa um grande problema associado com a atividade de
extra??o de ?leo bruto. O monitoramento dos n?veis de metais nos res?duos ? constante
e requer a utiliza??o de t?cnicas anal?ticas sens?veis. No entanto, a determina??o de
elementos tra?o muitas vezes pode exigir uma etapa de pr?-concentra??o. O objetivo
deste trabalho foi desenvolver um m?todo anal?tico simples e r?pido para a extra??o e
pr?-concentra??o baseada no fen?meno de extra??o no ponto nuvem para a
determina??o do Cd, Pb e Tl em ?gua produzida amostras por Espectrometria de
Absor??o de alta resolu??o com fonte continua e atomiza??o em forno de grafite. Um
planejamento Box Behnken foi usado para obter a condi??o ideal de extra??o dos
analitos. Os fatores avaliados foram: concentra??o do agente complexante (o,odietilditilfosfato
am?nio, DDTP), a concentra??o do ?cido clor?drico e concentra??o do
surfactante (Triton X -114). A condi??o ideal de extra??o foi obtida com: 0,6% m v
-1
DDTP, HCl 0,3 mol L-1
e 0,2% m v
-1
de Triton X - 114 para o Pb; 0,7% m v
-1 DDTP,
HCl 0,8 mol L-1
e 0,2% m v
-1
Triton X-114 para Cd. Para o Tl foi evidenciado que
melhor condi??o de extra??o se d? com aus?ncia de DDTP, as condi??es de extra??o
foram ent?o HCl 1,0 mol L-1
e 1,0% m v
-1
de Triton X - 114. Os limites de detec??o
para o m?todo proposto, foram 0,02 ?g L-1
, 0,004 ?g L-1
e 0,06 ?g L-1
para o Pb, Cd e
Tl, respectivamente. Os fatores de enriquecimento foram superiores a 10 vezes. O
m?todo foi aplicado para a ?gua produzida da bacia Potiguar, e testes de adi??o e
recupera??o foram realizados, e valores ficaram entre 81% e 120%. A precis?o foi
expressa com desvio padr?o relativo (RSD) foi inferior a 5% === Produced water is a major problem associated with the crude oil extraction
activity. The monitoring of the levels of metals in the waste is constant and requires the
use of sensitive analytical techniques. However, the determination of trace elements can
often require a pre-concentration step. The objective of this study was to develop a
simple and rapid analytical method for the extraction and pre-concentration based on
extraction phenomenon cloud point for the determination of Cd, Pb and Tl in produced
water samples by spectrometry of high resolution Absorption source continues and
atomization graphite furnace. The Box Behnken design was used to obtain the optimal
condition of extraction of analytes. The factors were evaluated: concentration of
complexing agent (o,o-dietilditilfosfato ammonium, DDTP), the concentration of
hydrochloric acid and concentration of surfactant (Triton X -114). The optimal
condition obtained through extraction was: 0,6% m v-1 DDTP, HCl 0,3 mol L-1
and
0,2% m v-1
of Triton X - 114 for Pb; 0,7% m v-1 DDTP, HCl 0,8 mol L-1
and 0,2% m v-1
Triton X-114 for Cd. For Tl was evidenced that best extraction condition occurs with
no DDTP, the extraction conditions were HCl 1,0 mol L-1
e 1,0% m v-1
de Triton X -
114. The limits of detection for the proposed method were 0,005 ?g L-1
, 0,03 ?g L-1
and
0,09 ?g L-1
to Cd, Pb and Tl, Respectively. Enrichment factors Were greater than 10
times. The method was applied to the water produced in the Potiguar basin, and addition
and recovery tests were performed, and values were between 81% and 120%. The
precision was expressed with relative standard deviation (RSD) is less than 5%
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