Determination of o-phthalic acid esters in water by chromatography–mass spectrometry with emulsion dispersive liquid–liquid microextraction preconcentration

Abstract

Using emulsion dispersive liquid–liquid microextraction preconcentration and injection of a large volume of an extract (10 μL), the limits of chromatographic–mass spectrometric detection of o-phthalic acid esters in water have been attained at the level 4 × 10^–6–1 × 10^–5 mg/L. The main source of the systemic error of the determination of impurities was found to be the release of o-phthalates from microparticles of chromatographic septum to the carrier gas. The extractant (n-octane) was purified by Rayleigh distillation. The independence of the concentration coefficient of the studied o-phthalates of concentration in the range (0.4–30) × 10^–4 mg/L has been demonstrated. The relative expanded uncertainty of the determination of o-phthalates has been calculated and equals 12–39%.