SOLID-PHASE EXTRACTION COUPLED WITH ELECTROCHEMICAL DETECTION FOR THEDETERMINATION OF THE HERBICIDE BROMOFENOXIM IN WATER SAMPLES AT LOW-MU-G AND SUB-MU-G I-1 LEVELS
Ig. Svegl et al., SOLID-PHASE EXTRACTION COUPLED WITH ELECTROCHEMICAL DETECTION FOR THEDETERMINATION OF THE HERBICIDE BROMOFENOXIM IN WATER SAMPLES AT LOW-MU-G AND SUB-MU-G I-1 LEVELS, Analyst, 121(12), 1996, pp. 1839-1843
The application of solid-phase extraction (SPE) as a preconcentration
and clean-up step with subsequent off-line flow injection amperometric
(FI-AD) or batch square-wave voltammetric (SWV) detection of the herb
icide bromofenoxim was developed. The selection bf an appropriate orga
nic eluent, some parameters influencing the efficiency of the SPE and
the electrochemical detection of bromofenoxim in the organic effluent
solution were thoroughly investigated, Undiluted acetonitrile with SWV
and acetonitrile-water (80 + 20) with FI-AD, both containing 0.1 mol
l(-1) LiClO4, were chosen as the most appropriate SPE eluents, The add
ition of LiClO4 as supporting electrolyte to the eluent and acidificat
ion of a water sample to 1 x 10(-3) mol l(-1) HClO4 (pH 3) prior to th
e SPE procedure were found to improve greatly the current response on
mercury drop (SWV) and mercury film (IT-AD) electrodes, Subsequent to
the SPE procedure, the effluents mere transferred to the voltammetric
cell or injected into the flow injection system without any further tr
eatment, The calibration plots obtained for bromofenoxim in pure water
samples were linear over the ranges 0.2-12.0 mu g l(-1) and 3.0-120 m
u g l(-1), with calculated detection limits of 0.05 and 1.5 mu g l(-1)
(100 ml samples), for the SPE-SWV and SPE-FI-AD procedures, respectiv
ely, The actual detection capabilities of-the proposed methods depend
on the mater sample volumes applied to the extraction cartridges, The
recoveries of the over-all procedures, applying spiked tap water sampl
es, and the corresponding RSDs were 92% and 6% (n = 6) and 121% and 9%
(n = 7) for SPE-SWV and SPE-FI-AD, respectively, The practical applic
ability of the proposed methods for the analysis of ground and tap wat
er samples was confirmed via an inter-laboratory test on a tap water s
ample containing five common pesticides including bromofenoxim.