Automated Magnetic Solid-Phase Extraction for Synthetic Food Colorant Determination
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Automated Magnetic Solid-Phase Extraction for Synthetic Food Colorant Determination Hao Wu 1 & Nannan Gao 1 & Lizhen Zhang 1 & Yunrong Li 1 & Yating Shi 1 & Liming Du 1
Received: 23 March 2015 / Accepted: 3 June 2015 # Springer Science+Business Media New York 2015
Abstract A new automated magnetic solid-phase extraction (MSPE) method was developed and combined with highperformance liquid chromatography (HPLC) and spectrophotometry for off-line and on-line quantitative enrichment and determination of synthetic food colorants in food samples. Fe3O4-poly (ionic liquid) core-shell microspheres were prepared as a sorbent to quickly extract analytes from aqueous samples. The entire MSPE process, including extraction, separation, elution, and cleaning, was automated using common equipment. The main parameters affecting the performance of MSPE and the automated process, such as absorbent, sample pH, eluent, flow rate, elution time, etc., were investigated in detail. Under the optimum experimental conditions, the limits of detection ranged between 4.1 and 14 ng/mL by off-line HPLC and were 220 ng/mL for the determination of amaranth by on-line spectrophotometry, with excellent reproducibility (intra- and inter-day relative standard deviations were less than 3.2 %). The developed method was successfully applied to the determination of colorants in food samples.
Keywords Automated magnetic solid phase extraction . Fe3O4-poly (ionic liquid) . Synthetic food colorants . High-performance liquid chromatography . Spectrophotometer . Flow injection
* Hao Wu [email protected] * Liming Du [email protected] 1
School of Chemistry and Material Science, Shanxi Normal University, Shanxi Linfen, People’s Republic of China 041004
Introduction Although magnetic solid phase extraction (MSPE) was first reported in 1999 (Šafařı́ková and Šafařı́k 1999), it has received considerable attention in recent years because of its potential applications in the analytical community. In this procedure, a magnetic sorbent is added to the sample solution and the target analyte is selectively adsorbed onto the surface of the magnetic beads, which are then separated from the aqueous solution by the application of an external magnetic force to the extraction vessel. The target analyte is then desorbed using a suitable solvent for further determination. Compared to conventional solid-phase extraction (SPE), sample pretreatment is greatly simplified through the use of MSPE, which eliminates the need for packing the column with sorbent in the case of batch-mode operation because the phase separation can be quickly and easily accomplished by applying an external magnetic field (Aguilar-Arteaga et al. 2010; Wierucka and Biziuk 2014). Automation is an important factor for practical applications of sample pretreatment; it allows the extraction and solvent desorption steps of multiple samples to be performed in parallel, leading to a time-efficient method (Hutchinson et al. 2007). This attribute is particularly important to analytical laboratories with high sample
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