Electroanalytical Methodology for the Direct Determination of 2,4-Dichlorophenoxyacetic Acid in Soil Samples Using a Graphite-Polyurethane Electrode

Table 3

Concentration of 2,4-D in the soil solutions extracted with the porous cup extractor system in three depths for soils AM1 and AM2.

Sample	Concentration of 2,4-D (mg L^−1)
	AM1			AM2
	25 cm	50 cm	75 cm	25 cm	50 cm	75 cm
SH^a	ND^c	ND	ND	ND	ND	ND
BR^b	ND	SA^d	ND	SA	SA	SA
24 h	1.07±0.01	SA	ND	1.52±0.03	ND	0.73±0.02
48 h	0.67±0.07	SA	SA	1.02±0.07	1.19±0.03	0.85±0.06
72 h	0.86±0.08	SA	0.62±0.03	0.62±0.02	SA	0.55±0.07
7 days	ND	SA	SA	ND	0.17±0.01	0.17±0.03
14 days	ND	0.19±0.02	ND	ND	ND	ND
30 days	ND	0.17±0.05	ND	ND	ND	ND
52 days	ND	ND	ND	SA	ND	ND
60 days	ND	ND	ND	ND	ND	ND
71 days	ND	ND	ND	SA	0.16±0.03	ND
73 days	ND	SA	ND	ND	ND	ND
76 days	ND	ND	ND	ND	ND	ND
85 days	ND	ND	ND	ND	SA	ND

aSample without herbicide (SH); ^bblank sample (BR); ^cconcentration below the quantification limit of the technique (ND); ^dno sample—volume extracted was not enough for the analysis (SA).