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A simple and sensitive cloud point extraction
method has been developed for the preconcentration
of ultra-trace amounts of gold as a prior step
to its determination by electrothermal atomic absorption
spectrometry. It is based on the extraction of gold
in hydrochloric acid medium using the non-ionic surfactant
polyethyleneglycolmono-p-nonylphenylether
(PONPE 7.5) without adding a chelating agent. The
preconcentration of a 50mL sample solution was thus
enhanced by a factor of 200. The resulting calibration
graph was linear in the range of 10–200 ng L1 with a
correlation coefficient of 0.9993. The limit of detection
(3s) obtained under optimal conditions was 2.0 ng L1.
The relative standard deviation for 10 replicate determinations
at a 100 ng L1 Au level was 3.6%. The
method was applied to the ultra-trace determination
of gold in water and copper samples.
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