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This article describes the assessment of possible allelopathic potential of organic extracts obtained from leaves of Canavalia ensiformis under laboratory conditions. Furthermore, a systematic evaluation of these extracts was carried out using specific protocols developed in capillary electrophoresis (CE) to determine some groups of secondary metabolites. After the identification and quantification of compounds, the effects of compounds on germination of some common weeds was investigated, which are becoming a real problem in pastures in the state of Pará, Brazil.

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One hundred twenty five congeners of CDF off 135 theoretically possible were quantified in seven of various type Halowax formulations but still 45 co-eluted under the gas chromatographic conditions applied. The total CDFs concentration of Halowax formulations was between 250 and 16,000 ng/g. The compositional profile of CDF homologue groups of the Halowaxes frequently followed a degree of chlorination of the parent chloronaphthalene mixture and an exception was Halowax 1031. The compositional profile of many isomers of trichlorodibenzofuran, found and often highly abundant, was characteristic to majority of the formulations examined, and each of them demonstrated to have its own pattern but mysterious to explain remained Halowax 1031. In term of dioxin-like toxicity the most potent due to CDFs content was Halowax 1014 with 210 ng TCDD TEQ/g and next was Halowax 1013 with 36 ng TEQ/g, while between 1.3 and 5.0 ng TEQ/g were for other formulations. A tentative estimation made implies that the net total CDFs production due to manufacture of the technical CNs in the XX century could reach an amount between 420 kg (median) and 825 kg (mean), and for most toxic dioxin-like congeners between 705 g (median) and 5700 g (mean) TCDD TEQ, while for the worst case of Halowax 1014 alone scenario it could be 750 kg of the total CDFs and 16 kg of TCDD TEQ for most toxic congeners.