Mn(ii) imprinted 3-mercaptopropyltrimethoxysilane (MPTS)-silica coated capillary microextraction on-line hyphenated with inductively coupled plasma mass spectrometry for the determination of trace Mn(ii) in biological samples

Abstract

Mn(II) imprinted 3-mercaptopropyltrimethoxysilane (MPTS)-silica coated capillary was synthesized by sol–gel technique combining with a double-imprinting concept. The prepared capillary was employed for capillary microextraction (CME) of trace Mn(II) followed by on-line inductively coupled plasma mass spectrometry (ICP-MS) detection. This coating was in situ created on the inner wall of tetramethoxysilane (TMOS) coated silica capillary using a sol solution containing MPTS as the functional precursor, ethanol as the solvent and both Mn(II) and surfactant micelles (cetyltrimethylammonium bromide, CTAB) as the templates. The factors affecting on the CME of Mn(II) such as sample pH, sample flow rate and volume, elution solution and interfering ions have been investigated. Under the optimized conditions, the adsorption capacities of non-imprinted and imprinted capillary were found to be 1.24 and 2.38 μg m⁻¹, respectively. With a sampling frequency of 9 h⁻¹, an enrichment factor of 16.7 was obtained for Mn(II). The detection limit (3σ) based on three times the standard deviations of the blanks by seven replicates was 10.3 ng L ⁻¹ and the relative standard deviation (RSD) was 4.3% (c = 0.1 μg L⁻¹, n = 7). The proposed method was successfully applied for the determination of trace Mn(II) in serum samples and validated by two certified reference materials. The method is rapid, selective, sensitive and applicable for the analysis of trace Mn(II) in biological samples with limited sample volume.