Abstract
This paper describes a sequential injection analysis method, with detection by square wave voltammetry using a hanging mercury drop electrode, to determine the herbicide picloram in soil extracts (0.010 mol L-1 CaCl2). The method was applied for determination of the Freundlich parameters related to adsorption of picloram on a tropical soil sample. The major advantage of the proposed method over the conventional chromatographic methods is the high sampling throughput of 190 analyses per hour, with detection and quantification limits of 0.036 and 0.12 mg L-1, respectively. The Kf (0.0016 ± 0.0005 µmol1-1/n L1/n kg-1) and 1/n (0.85 ± 0.06) obtained by the proposed method did not differ from those determined by liquid chromatography with UV detection.
Highlights
Picloram (4-amino-3,5,6-trichloro-2-pyridinecarboxilic acid) is a synthetic organochlorine compound used in the salt form as a systemic herbicide for controlling annual weeds in crops, and in combination with 2,4-dichlorophenoxyacetic acid (2,4-D) or 2,4,5-trichlorophenoxyacetic acid (2,4,5‐T) against perennials on non-croplands for brush control.[1]
As the soil is a complex matrix and significant matrix effects have been observed by dos Santos et al.[16] to determine the herbicide atrazine in soil extracts by square wave voltammetry, special attention was given to determine picloram in soil extract
Voltammetric peaks of picloram lost intensity in 0.010 mol L-1 CaCl2 solutions from soil extracts compared to voltammetric peaks obtained in the same supporting electrolyte that had no contact with the soil (Figure 2)
Summary
Picloram (4-amino-3,5,6-trichloro-2-pyridinecarboxilic acid) is a synthetic organochlorine compound used in the salt form as a systemic herbicide for controlling annual weeds in crops, and in combination with 2,4-dichlorophenoxyacetic acid (2,4-D) or 2,4,5-trichlorophenoxyacetic acid (2,4,5‐T) against perennials on non-croplands for brush control.[1]. To correct for matrix effects, calibration of the system was made in soil extracts prepared in the same medium used to perform the adsorption experiments.
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