No abstract

This study proposes an efficient analytical methodology using a biosorbent (cork) as an extraction phase in disposable pipette extraction technique for the rapid determination of the emerging contaminants methyl paraben, ethyl paraben, benzophenone, 3‐(4‐methylbenzylidene) camphor and 2‐(ethylhexyl)‐4‐(dimethylamino) benzoate in lake water samples using high‐performance liquid chromatography with diode array detection. The optimized conditions were comprised of 800 μL of sample, three cycles of 30 s each for the extraction, pH 6, addition of 30% w/v of NaCl. For the desorption step, the optimized desorption conditions were achieved with 100 μL of a mixture comprised of 50% methanol and 50% acetonitrile v/v, using one cycle of 30 s. Excellent analytical performance was achieved with limits of detection of 0.6 μg/L for methyl paraben to 1.4 μg/L for 3‐(4‐methylbenzylidene) camphor, and the limit of quantitation varied from 2 μg/L for methyl paraben to 4.3 μg/L 3‐(4‐methylbenzylidene) camphor, respectively. The correlation coefficients ranged from 0.9962 for ethyl paraben to 0.9980 for methyl paraben. The method accuracy varied from 71–132%, and the intraday precision ranged from 3 to 23% (n = 3) and interday from 9 to 23% (n = 9). The robustness was evaluated through Youden and Lenth's methods and indicated no significant variations in the results.

In this study, a multiresidue analytical methodology based on magnetic ionic liquid as extraction phase and dispersive liquid‐liquid microextraction, was developed for the determination of organic contaminants in river water samples by high‐performance liquid chromatography with diode array detection (HPLC‐DAD). Experimental conditions were carefully optimized using univariate and multivariate designs. A simplex‐lattice design was adopted for the optimization of disperser solvent, univariate planning was applied to pH optimization and a central composite design was used for the optimization of magnetic ionic liquid mass, extraction time and NaCl concentration added to the samples. The optimal extraction conditions were a mixture of acetonitrile/methanol 50:50 v/v as disperser solvent, pH adjusted to 6.0, 10 mg of magnetic ionic liquid, and extraction time of 180 s. The analytical parameters of merit were determined under the optimized conditions, and very acceptable results were achieved, with limits of detection ranging from 1.5 to 15 μg L−1 and determination coefficients (R2) higher than 0.992 for all 15 analytes. Precision varied from 8.6 to 17.8% and from 0.4 to 19.3% for interday (n = 9) and intraday (n = 3) assays, respectively. Relative recoveries varied from 56 to 123% in two aqueous samples, both collected in Camboriú city, Santa Catarina, Brazil.