Speciation of lead compounds in fish by capillary electrophoresis-inductively coupled plasma mass spectrometry

Abstract

A capillary electrophoresis-inductively coupled plasma mass spectrometric (CE-ICP-MS) method for lead speciation application is described. Sample containing ionic lead compounds were subjected to electrophoretic separation before injection into the micro-concentric nebulizer (CEI-100). The species studied include inorganic lead (Pb^II), trimethyl lead (TML) and triethyl lead (TEL). The separation has been achieved on a 70 cm length × 75 μm id fused silica capillary. The electrophoretic buffer used is 15 mmol l⁻¹ Tris (pH 8.25) containing 10 mmol l⁻¹ SDS (sodium dodecyl sulfate), 0.2 mmol l⁻¹ EDTA and 2% v/v methanol, while the applied voltage is set at +26 kV. The lead species in biological tissues are extracted into 1% m/v EDTA solution taken in a closed centrifuge tube and kept on a water bath, using microwaves at 70 °C for 10 min. The extraction efficiencies of individual lead species added to the sample at 2 μg Pb g⁻¹ level are between 97% and 102%. The detection limits of the species studied are in the range 0.2–0.6 ng Pb ml⁻¹. The procedure has been applied for the speciation analysis of two reference materials namely dogfish liver tissue (NRCC DOLT-3) and oyster tissue (NIST SRM 1566a) and two real-world samples.