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Desenvolvimento de metodologia de extra??o e pr?-concentra??o utilizando sistema microemulsionado para determina??o de Cd, Co, Cu, Ni, Pb e Tl em ?guas naturais e produzidas por HR-CS AASCosta, Emily Cintia Tossi de Ara?jo 23 September 2013 (has links)
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Previous issue date: 2013-09-23 / A contamina??o de ?guas naturais por metais tornou-se assunto de interesse p?blico mundial por serem considerados biocumulativos. A determina??o e o monitoramento de contaminantes met?licos em ?guas ? uma tarefa que deve ser cont?nua e por isto a import?ncia do desenvolvimento, modifica??o e otimiza??o de metodologias anal?ticas capazes de realizar a determina??o dos v?rios contaminantes met?licos em ambientes naturais, pois em muitos casos, a instrumenta??o dispon?vel n?o apresenta sensibilidade anal?tica suficiente para a determina??o de tra?os. Neste estudo, um m?todo de extra??o e pr?-concentra??o utilizando um sistema microemulsionado, no equil?brio de Winsor II foi testado e otimizado para a determina??o dos metais Co, Cd, Pb, Tl, Cu e Ni por Espectrometria de absor??o at?mica de alta resolu??o com fonte cont?nua e atomiza??o em forno de grafite e chama (HR-CS AAS). A otimiza??o do programa de temperatura para o forno de grafite foi realizada atrav?s de curvas de pir?lise e atomiza??o para cada analito sem e com o uso de diferentes modificadores qu?micos. Cd e Pb tiveram condi??es ?timas com modificador permanente Ru, pir?lise em 700?C e atomiza??o em 1700?C, para Tl solu??o Pd/Mg foi o melhor modificador, temperaturas 600?C e 1700?C de pir?lise e atomiza??o, respectivamente e para o Co pir?lise em 800?C e atomiza??o ? 2400?C sem uso de modificador qu?mico, por?m W foi empregado como modificador permanente a fim de se prolongar o tempo de vida ?til do forno. Cu e Ni foram analisados na chama ap?s pr?-concentra??o. Avaliou-se tamb?m fatores que influenciam a efici?ncia de extra??o, atrav?s do efeito salting out. Como compromisso, 6 g L-1 de Na e 1% de HNO3 (v/v) foi definido. Para determina??o do ponto ?timo de extra??o, um planejamento centroide-simplex foi aplicado, sendo escolhido como compromisso as seguintes propor??es: 70% fase aquosa, 10% fase ?leo e 20% Cotensoativo/Tensoativo (C/T = 4). Ap?s extra??o, os metais foram determinados e as Figuras de m?rito obtidas para o m?todo proposto foi: 0,1 a 10 ?g L-1 de faixa linear, LOD 0,094, 0,011, 0,057 e 0,050 ?g L-1 para Pb, Cd, Tl e Co, respectivamente. Testes de adi??o e recupera??o na amostra certificada apresentaram valores de recupera??o ap?s extra??o de 105 e 101% para Pb e Cd, respectivamente, e nas amostras fortificadas a recupera??o para os analitos ficou entre 107 e 108% comprovando que o m?todo proposto pode ser utilizado na extra??o, possibilitou a separa??o dos metais de matrizes complexas, e ainda com bom fator de pr?-concentra??o. / The determination and monitoring
of metallic contaminants in water is a task that must
be continuous, leading to the importance of
the development, modification and optimization
of analytical methodologies capab
le of determining the various
metal contaminants in natural
environments, because, in many cases, the ava
ilable instrumentation does not provide enough
sensibility for the determination of trace values
. In this study, a method of extraction and pre-
concentration using a microemulsion system with
in the Winsor II equilibrium was tested and
optimized for the determination of Co, Cd, P
b, Tl, Cu and Ni through the technique of high-
resolution atomic absorption spectrometry
using a continuum source (HR-CS AAS). The
optimization of the temperature program for
the graphite furnace (HR-CS AAS GF) was
performed through the pyrolysis and atomization
curves for the analytes Cd, Pb, Co and Tl
with and without the use of different chemical
modifiers. Cu and Ni we
re analyzed by flame
atomization (HR-CS F AAS) after pre-concentr
ation, having the sample introduction system
optimized for the realization of discrete sampling. Salinity and pH levels were also analyzed
as influencing factors in the efficiency
of the extraction. As final numbers, 6 g L
-1
of Na (as
NaCl) and 1% of HNO
3
(v/v) were defined. For the determination of the optimum extraction
point, a centroid-simplex statistical plan was a
pplied, having chosen as the optimum points of
extraction for all of the analytes, the follo
wing proportions: 70%
aqueous phase, 10% oil
phase and 20% co-surfactant/surfactant (C/S
= 4). After extraction, the metals were
determined and the merit figures obtained
for the proposed method were: LOD 0,09, 0,01,
0,06, 0,05, 0,6 and 1,5 ?g L
-1
for Pb, Cd, Tl, Co, Cu and Ni, re
spectively. Line
ar ranges of ,1-
2,0 ?g L
-1
for Pb, 0,01-2,0 ?g L
-1
for Cd, 1,0 - 20 ?g L
-1
for Tl, 0,1-5,0 ?g L
-1
for Co, 2-200
?g L
-1
and for Cu e Ni 5-200 ?g L
-1
were obtained. The enrichment factors obtained ranged
between 6 and 19. Recovery testing
with the certified sample show
ed recovery values (n = 3,
certified values) after extraction of 105
and 101, 100 and 104% for Pb, Cd, Cu and Ni
respectively. Samples of sweet waters of lake
Jiqui, saline water from Potengi river and water
produced from the oil industry (PETROBRAS) were
spiked and the recovery (n = 3) for the
analytes were between 80 and 112% confirming th
at the proposed method
can be used in the
extraction. The proposed method enabled the sepa
ration of metals from complex matrices,
and with good pre-concentration factor, consistent with the MPV (allowed limits) compared
to CONAMA Resolution No. 357/2005 which regulat
es the quality of fresh surface water,
brackish and saline water in Brazil.
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Determina??o de CD, PB, e TL em ?gua produzida por HR-CS GF AAS ap?s extra??o em ponto nuvem / Determination of Cd, Pb, and Tl produced water by HR-CS GF AAS after extraction point in cloudBezerra, Breno Gustavo Porf?rio 03 November 2014 (has links)
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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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