The development of adsorbent materials is today one of the most recent and important areas of research in analytical chemistry. Many of the sample preparation techniques prior to chromatographic analysis involve solid phase extraction processes and for this reason new adsorbents are required with more selective and adsorptive, economical and environmentally friendly characteristics. In view of this, this research proposes the use of chitosan, a biopolymer, as a low-cost adsorbent in the solid phase extraction of three herbicides (metribuzin, prometryn and terbuthylazine) from aqueous samples. Chitosan was obtained from shrimp waste applying a new extraction methodology, which consisted mainly of using a saturated solution of CaCl2 in methanol and water (CaCl2-MeOH-H2O system), agitation, and ultrasound to induce the reaction of deacetylation of the chitin present in the wastes. The extracted chitosan presented different properties compared to the chitosan obtained by the conventional method. The main difference was the formation of calcite, the most stable polymorph of CaCO3, in its structure. Its surface was composed of pores and in terms of thermal stability, a much more stable compound was obtained. The application of chitosan as an adsorbent in solid phase extraction showed that the extracted chitosan can be applied in metribuzin, prometryn, and terbuthylazine extraction processes with recovery efficiencies close to 100%. The methodology for obtaining chitosan had the advantage that the stages of the conventional extraction process were reduced and the use of reagents at high concentrations was minimized. The extracted chitosan is a low-cost adsorbent that can be efficiently used in the solid phase extraction. The compound obtained with the proposed methodology adjusts to the new adsorbent trends for the sample preparation prior to chromatographic analysis. Besides, it is an adsorbent with thermal stability, with pores on its surface and an adequate adsorption capacity. In addition, it is an ecological, biodegradable, and economic adsorbent.


_The development of adsorbent materials is today one of the most recent and important areas of research in analytical chemistry. Many of the sample preparation techniques prior to chromatographic analysis involve solid phase extraction processes and for this reason new adsorbents are required with more selective and adsorptive, economical and environmentally friendly characteristics. In view of this, this research proposes the use of chitosan, a biopolymer, as a low-cost adsorbent in the solid phase extraction of three herbicides (metribuzin, prometryn and terbuthylazine) from aqueous samples. Chitosan was obtained from shrimp waste applying a new extraction methodology, which consisted mainly of using a saturated solution of CaCl~2~ in methanol and water (CaCl~2~-MeOH-H~2~O system), agitation, and ultrasound to induce the reaction of deacetylation of the chitin present in the wastes. The extracted chitosan presented different properties compared to the chitosan obtained by the conventional method. The main difference was the formation of calcite, the most stable polymorph of CaCO~3~, in its structure. Its surface was composed of pores and in terms of thermal stability, a much more stable compound was obtained. The application of chitosan as an adsorbent in solid phase extraction showed that the extracted chitosan can be applied in metribuzin, prometryn, and terbuthylazine extraction processes with recovery efficiencies close to 100%. The methodology for obtaining chitosan had the advantage that the stages of the conventional extraction process were reduced and the use of reagents at high concentrations was minimized. The extracted chitosan is a low-cost adsorbent that can be efficiently used in the solid phase extraction. The compound obtained with the proposed methodology adjusts to the new adsorbent trends for the sample preparation prior to chromatographic analysis. Besides, it is an adsorbent with thermal stability, with pores on its surface and an adequate adsorption capacity. In addition, it is an ecological, biodegradable, and economic adsorbent._


Preconcentración de triazinas usando quitosana mineralizada como fase sólida

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