Analysis of chlorophenols, bisphenol-A, 4-tert-octylphenol and 4-nonylphenols in soil by means of ultrasonic solvent extraction and stir bar sorptive extraction with in situ derivatisation.

A novel method based on ultrasonic solvent extraction and stir bar sorptive extraction for the analysis of phenolic organic pollutants including chlorophenols, bisphenol-A, 4-tert-octylphenol and 4-nonylphenol in soil samples was developed. The different parameters that affect both the extraction of analytes from the soil samples, such as solvent selection, extraction time, and the partitioning from the solvent/water mix to poly(dimethylsiloxane) (PDMS) were studied. The final selected conditions consisted of the extraction of 1g of soil with 15 mL methanol by sonication for 30 min. The methanol extract was mixed with 85 mL of Milli-Q water and extracted by means of stir bar sorptive extraction with in situ derivatisation. The stir bars were analyzed by thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS). The effects of the matrix on the recovery of the various pollutants under the developed method were studied using two soils with very different physicochemical properties. Method sensitivity, linearity, repeatability, and reproducibility were also studied. Validation and accuracy of the method were conducted by analyzing two commercial certified reference materials and by comparing the analysis of real samples with the proposed method and a classical method using pressurized solvent extraction (PSE)-GC-MS. The main advantage of this method is a substantial solvent reduction. For the extraction of only 1g of solid sample allowing limits of detection ranging from 0.2 to 1.7 microg kg(-1) dw. Repeatability and reproducibility variation were lower than 20% for all investigated compounds. Results of the certified reference materials and the real samples verify the high accuracy of this method.

Stir bar sorptive extraction for the analysis of short-chain chlorinated paraffins in water.

An optimised method using stir bar sorptive extraction (SBSE) and a thermal desorption-GC-electron capture detector (GC-ECD) for the determination of short-chain chlorinated paraffins from water samples was developed. Recoveries near to 100% were obtained by using 20 mm x 0.5 mm (length x film thickness) PDMS commercial stir bars from 200 mL spiked water samples and 20% methanol addition with an extraction period of 24 h. Method sensitivity, linearity and precision were evaluated for surface water and wastewater spiked samples. A LOD of 0.03 and 0.04 microg/L was calculated for surface and wastewater, respectively. The precision of the method given as an RSD was below 20% for both matrices. The developed method was applied for the analysis of two real samples from a contaminated river and a wastewater treatment plant. Results were in accordance with those obtained using a previously developed method based on solid phase microextraction (SPME).