Solid-phase microextraction for the determination of iron organic compounds in seawaters and soils by gas chromatography coupled to microwave-induced plasma with atomic emission detection spectrometry

Abstract

A rapid solvent-free method for determining ferrocene and five derivatives (1,1´-dimethylferrocene, ferrocenecarboxaldehyde, acetylferrocene, ferroceneacetonitrile and benzoylferrocene) in seawaters and soils using direct immersion solid-phase microextraction (DI-SPME) and gas chromatography coupled to microwave-induced plasma with atomic emission detection (GC-MIP-AED) is developed. The bonded divinylbenzene/Carboxen/polydimethylsiloxane commercial fiber provided good extraction efficiency in the DI mode for all the compounds, applying a fiber time exposure of 15 min at ambient temperature. The analytes were previously isolated from the soil matrices (0.2 g) by ultrasound-assisted extraction using 7 mL of 0.1 M acetate/acetic buffer solution. The absence of a matrix effect was confirmed in the case of seawaters, which permitted calibration against aqueous standards. However, the standard additions method was required for soil analysis. Detection limits (DLs) were in the 3–110 pg mL−1 and 0.9–4 ng g − 1 for seawater and soils, respectively. Analysis of the different samples using the proposed DI-SPME-GC-AED method only provided an analytical signal for ferrocene in one seawater sample at a concentration near its DL (3 pg mL−1).