The analysis of estrogenic compounds by flow injection analysis with amperometric detection using a boron-doped diamond electrode

• Estrone was detected in standards and spiked water samples by FIA-EC using a diamond electrode.
• Amperometric detection was accomplished at 1.15 V vs. Ag/AgCl with no electrode structural change.
• The short-term response reproducibility was 2.3% RSD.
• Response linearity was found between 0.050 and 2.0 μmol L−1 with a detection limit of 0.050 μmol L−1.
• Response recoveries were 94%–110% in spiked city tap water and 88%–98% in spiked river water.

We report on the use of flow injection analysis with amperometric detection (FIA-EC) to evaluate the potential of using diamond electrodes for the analysis of three estrogenic compounds: estrone, 17-β-estradiol, and estriol. Amperometric detection was performed using a cathodically pretreated boron-doped diamond electrode that offered low background current, relatively low limits of detection, and good response reproducibility and stability. For all three compounds, response linearity was observed over the concentration range tested, 0.10 to 3.0 μmol L−1, the sensitivity was ca. 10 mA L mol−1, and the minimum concentration detection (S/N≥3) was 0.10 μmol L−1 (~27 μg L−1). The response variability with multiple injections was ca. 10% (RSD) over 20 injections. For estrone, the oxidation reaction on diamond does not proceed through an adsorbed state like it does on glassy carbon. After an initial current attenuation, the diamond electrode exhibited a stable response (oxidation current) for 3 days of continuous use, indicative of minimal surface contamination or fouling by reaction intermediates and products. The method for estrone was assessed using spiked city tap and local river water. Estrone recoveries in spiked city and river water samples presented standard deviations of less than 10%. In summary, the FIA-EC method with a diamond electrode enables sensitive, reproducible, stable, quick, and inexpensive determination of estrogenic compounds in water samples.

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