Molecularly imprinted solid-phase extraction combined with ultrasound-assisted dispersive liquid–liquid microextraction for the determination of four Sudan dyes in sausage samples
ABSTRACT A simple and highly selective molecularly imprinted solid-phase extraction (MISPE) combined with ultrasound-assisted dispersive liquid-liquid microextraction (DLLME) was developed for the determination of four Sudan dye (I, II, III, and IV) residues in sausage products. The novel molecularly imprinted microspheres (MIMs) synthesized by aqueous suspension polymerization using phenylamine-naphthol as the dummy template show high affinity to the four Sudan dyes and were applied as selective sorbents of MISPE-DLLME to overcome the drawbacks of template leakage in quantitative analysis. Good linearity was obtained in a range of 0.005-2.0 μg g(-1) and the average recoveries of the four Sudan dyes at three spiked levels ranged from 86.3 to 107.5%. The MISPE-DLLME-HPLC protocol significantly improved the purification and enrichment of the analytes and eliminated the template leakage of the conventional MISPE on quantitative analysis.
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ABSTRACT: A novel colorimetric sensor for cholesterol assay was constructed by combining a molecular imprinting technique with photonic crystals. The molecularly imprinted photonic hydrogel (MIPH) film was prepared by a non-covalent, self-assembly approach using cholesterol as a template molecule, and exhibited a highly ordered three-dimensional macroporous structure characterized by scanning electron microscopy under the optimized imprinting conditions. Various factors affecting rebinding of cholesterol are discussed along with recognition specificity studies on its analogues of stigmasterol and ergosterol through estimation of UV-Vis and electrochemical impedance spectroscopy. The MIPH film generated a significantly readable optical signal directly self-reporting within less than 2 min upon binding cholesterol. The colorimetric measurement of cholesterol concentration strongly relies on the fact that the blue shift effect of the Bragg diffraction peak of the MIPH is gradually enlarged with the increase of cholesterol amounts. The detection level approached 10−13 g mL−1, which is comparable to that of fluorescence measurements. The simultaneous possession of high selectivity, high sensitivity, high stability, easy operation and being label-free enables this sensor to be potentially applicable for rapid on-site detection of trace cholesterol.Journal of Materials Chemistry 11/2011; 21(48):19267-19274. DOI:10.1039/C1JM14230E · 7.44 Impact Factor
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ABSTRACT: In this paper, a highly selective sample cleanup procedure combing dummy molecular imprinting and solid-phase extraction (DMI-SPE) was developed for the simultaneous isolation and determination of five phthalate esters in plastic bottled beverages. The new imprinted microspheres were synthesized via precipitation polymerization using diisononyl phthalate as a dummy template that showed high selectivity and affinity to the five kinds of phthalate esters and were successfully applied as selective sorbents of DMI-SPE for the simultaneous determination of the phthalate esters from plastic bottled beverages. Good linearity was obtained in a range of 5.0-750.0 μg/L, and the average recoveries of the five phthalate esters at three spiked levels ranged from 84.3 to 96.2% with the relative standard deviations less than 5.49%. The developed extraction protocol eliminated the effect of template leakage on quantitative analysis and could be applied for the determination of phthalate esters in complicated functional beverages products.Journal of Agricultural and Food Chemistry 05/2012; 60(22):5524-31. DOI:10.1021/jf300660m · 3.11 Impact Factor
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ABSTRACT: A vortex-assisted ionic liquid microextraction method coupled with ultra fast liquid chromatographic separation and detection was developed for the analysis of three aromatic amines, 4-chloroaniline, 1-naphthylamine and 4-aminobiphenyl, in environmental water samples. 1-Hexyl-3-methylimidazolium hexafluorophosphate [C6MIM][PF6] was used as the extraction solvent as it can disperse in water completely and quickly with the aid of vortex mixing. A dispersive solvent was not required. Several parameters such as type and volume of extraction solvent, vortex velocity, extraction time, centrifugation time, pH of sample solution and ionic strength in sample solution were investigated. Under the optimized conditions, the intra-day and inter-day precision of the proposed method were 2.3–3.5% (n = 5) and 2.8–5.3% (n = 5), respectively. The limits of detection and quantification were in the range of 0.24–0.57 μg L−1 and 0.80–1.90 μg L−1, respectively. The proposed method was applied in the determination of three aromatic amines in several real water samples. Acceptable recoveries of the analytes, ranging from 79% to 111% (the relative standard deviations ≤6.0%), were obtained.Analytical methods 06/2012; 4(7):2074-2080. DOI:10.1039/C2AY25056J · 1.94 Impact Factor