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Amperometric and spectrophotometric determination of carbaryl in natural waters and commercial formulations
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Orientador(es)
Resumo(s)
The work presented describes the development
and evaluation of two flow-injection analysis (FIA) systems
for the automated determination of carbaryl in spiked
natural waters and commercial formulations. Samples are
injected directly into the system where they are subjected
to alkaline hydrolysis thus forming 1-naphthol. This product
is readily oxidised at a glassy carbon electrode. The
electrochemical behaviour of 1-naphthol allows the development
of an FIA system with an amperometric detector
in which 1-naphthol determination, and thus measurement
of carbaryl concentration, can be performed. Linear response
over the range 1.0×10–7 to 1.0×10–5 mol L–1, with a
sampling rate of 80 samples h–1, was recorded. The detection
limit was 1.0×10–8 mol L–1. Another FIA manifold was
constructed but this used a colorimetric detector. The methodology
was based on the coupling of 1-naphthol with phenylhydrazine
hydrochloride to produce a red complex which
has maximum absorbance at 495 nm. The response was
linear from 1.0×10–5 to 1.5×10–3 mol L–1 with a detection
limit of 1.0×10–6 mol L–1. Sample-throughput was about
60 samples h–1. Validation of the results provided by the
two FIA methodologies was performed by comparing
them with results from a standard HPLC–UV technique.
The relative deviation was <5%. Recovery trials were also
carried out and the values obtained ranged from 97.0 to
102.0% for both methods. The repeatability (RSD, %) of
12 consecutive injections of one sample was 0.8% and
1.6% for the amperometric and colorimetric systems, respectively.
Descrição
Palavras-chave
Amperometry Spectrophotometry Carbaryl Pesticides Flow-injection analysis
Contexto Educativo
Citação
Editora
Springer-Verlag