Can solid-phase microextraction replace solvent extraction for water analysis in fish bioconcentration studies with...

Area of Science:

• Environmental Chemistry
• Ecotoxicology
• Analytical Chemistry

Background:

• Conventional solvent extraction methods for analyzing hydrophobic organic chemicals (HOCs) in fish bioconcentration studies can be labor-intensive and may not fully capture the bioavailable fraction.
• Understanding the freely dissolved concentrations of HOCs is crucial for accurate assessment of sorption, bioavailability, and bioconcentration factors (BCFs).

Purpose of the Study:

• To evaluate automated solid-phase microextraction (SPME) as an alternative to liquid-liquid extraction (LLE) for HOC analysis in fish bioconcentration studies.
• To investigate the capability of SPME for simultaneous extraction of total and freely dissolved HOC concentrations.
• To assess the impact of freely dissolved concentrations on BCF calculations and the relationship between BCF and hydrophobicity (log KOW).

Main Methods:

• Automated solid-phase microextraction (SPME) was employed for extracting three HOCs (log KOW 5.5-7.8) from water in flow-through studies with rainbow trout (Oncorhynchus mykiss).
• SPME extraction was compared against conventional liquid-liquid extraction (LLE) for total HOC concentrations.
• Simultaneous extraction of total and freely dissolved HOC concentrations using SPME was performed.

Main Results:

• Total HOC concentrations extracted by SPME were comparable to those obtained by LLE.
• SPME successfully enabled the simultaneous extraction of both total and freely dissolved HOC concentrations.
• Accounting for freely dissolved concentrations significantly increased the BCF for PCB 153, highlighting the underestimation risk when using total concentrations.
• BCF values calculated using freely dissolved concentrations did not show a linear correlation with log KOW above 5-6, suggesting other influencing factors.

Conclusions:

• Automated SPME is a suitable alternative to LLE for analyzing highly hydrophobic organic chemicals in fish bioconcentration studies.
• SPME's ability to measure freely dissolved concentrations provides critical data for accurate bioavailability and BCF assessments.
• Further research is needed to elucidate factors influencing BCFs beyond sorption and freely dissolved concentrations, particularly for highly hydrophobic compounds.