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  • Extraction and stability of pesticide multiresidues from natural water on a mixed-mode admicellar sorbent.

Extraction and stability of pesticide multiresidues from natural water on a mixed-mode admicellar sorbent.

Journal of chromatography. A (2012-06-26)
Noelia Luque, Soledad Rubio
ABSTRACT

The suitability of a mixed-mode sorbent made up of admicelles of sodium dodecyl sulphate (SDS) and tetrabutylammonium (TBA) to extract and preserve pesticides from river and underground water was assessed. Pesticides belonging to different structural groups (i.e. triazines, carbamates, phenylureas, anilides, chloroacetanilides, organophosphorus and phenoxyacids), most of them well known by their instability, were selected for this purpose. Extraction of pesticides with the admicellar sorbent was optimized. Percolation of 250 mL of sample through the SPE cartridge, elution with 1 mL of methanol (neutral and basic pesticides) or 2 mL of 0.3M NaOH:methanol (90:10, v/v) (acidic pesticides) and direct analysis of the extract by liquid chromatography/UV detection, permitted to obtain method detection limits in the range 2-60 ng L(-1). Their degradation on the SPE cartridges after sample percolation was investigated under a variety of experimental conditions, namely darkness, natural illumination and different temperatures (room temperature, 4 °C and -20 °C) for 3 months. Under darkness, most of pesticides were stable for 1 month at room temperature and 3 months at 4 °C. Only atriazine and clorfenvinfos did not follow this general behaviour. No influence of matrix components on the stabilization of pesticides in the admicellar sorbent was observed. The stabilizing capability of surfactant aggregates surpassed that of C18 and black carbon and was similar to that obtained in some polymeric materials, which have the disadvantage of requiring large volumes of solvents for analyte elution. The stabilization of pesticides on the admicellar sorbent was long enough to permit easy shipping and storage of the cartridges in monitorization campaigns.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Tetrabutylammonium perchlorate, ≥95.0% (T)
Supelco
Tetrabutylammonium perchlorate, for electrochemical analysis, ≥99.0%
Sigma-Aldrich
Tetrabutylammonium hydrogensulfate, 97%
Sigma-Aldrich
Tetrabutylammonium hydroxide solution, 1.0 M in methanol
Supelco
Tetrabutylammonium hydroxide solution, ~40% in water, suitable for ion chromatography
Sigma-Aldrich
Tetrabutylammonium cyanide, 95%
Sigma-Aldrich
Tetrabutylammonium hydroxide solution, 53.5-56.5% in H2O
Sigma-Aldrich
Tetrabutylammonium cyanide, technical, ≥80%
Sigma-Aldrich
Tetrabutylammonium hydroxide solution, 40 wt. % in H2O
Sigma-Aldrich
Tetrabutylammonium phosphate monobasic solution, 1.0 M in H2O
Sigma-Aldrich
Tetrabutylammonium hydroxide solution, technical, ~40% in H2O (~1.5 M)
Sigma-Aldrich
Tetrabutylammonium azide
Sigma-Aldrich
Tetrabutylammonium bromide solution, 50 wt. % in H2O
Sigma-Aldrich
Tetrabutylammonium iodide, ≥99.0% (AT)
Sigma-Aldrich
Tetrabutylammonium iodide, reagent grade, 98%
Sigma-Aldrich
Tetrabutylammonium fluoride solution, 75 wt. % in H2O
Supelco
Tetrabutylammonium chloride, suitable for ion pair chromatography, LiChropur, ≥99.0%
Sigma-Aldrich
Tetrabutylammonium bisulfate, puriss., ≥99.0% (T)
Supelco
Tetrabutylammonium bromide, suitable for ion pair chromatography, LiChropur, ≥99.0%
Sigma-Aldrich
Tetrabutylammonium phosphate monobasic, puriss., 99% (T)
Sigma-Aldrich
Tetrabutylammonium bromide, ReagentPlus®, ≥99.0%
Sigma-Aldrich
Tetrabutylammonium fluoride solution, 1.0 M in THF
Supelco
Tetrabutylammonium bisulfate solution, suitable for ion pair chromatography, LiChropur, concentrate, ampule
Sigma-Aldrich
Tetrabutylammonium chloride, ≥97.0% (NT)
Supelco
Tetrabutylammonium iodide, suitable for ion pair chromatography, LiChropur, ≥99.0%
Sigma-Aldrich
Tetrabutylammonium bisulfate solution, ~55% in H2O
Supelco
Tetrabutylammonium bisulfate, suitable for ion pair chromatography, LiChropur, ≥99.0%
Sigma-Aldrich
Tetrabutylammonium bromide, ACS reagent, ≥98.0%
Sigma-Aldrich
Tetrabutylammonium nitrate, 97%