Simultaneous determination of acrylamide, asparagine and glucose in food using short chain methyl imidazolium ionic liquid based ultrasonic assisted extraction coupled with analyte focusing by ionic liquid micelle collapse capillary electrophoresis

摘要

Acrylamide (AA) is a known lethal neurotoxin and carcinogen. AA is formed in foods during the browning process by the Maillard reaction of glucose (GL) with asparagine (AS). For the first time, the simultaneous online preconcentration and separation of AA, AS and GL using analyte focusing by ionic liquid micelle collapse capillary electrophoresis (AFILMC) was presented. Samples were prepared in a 1-butyl-3-methylimidazolium bromide (BMIMBr) micellar matrix with a conductivity 4 times greater than that of the running buffer (12.5 mmol L-1 phosphate buffer at pH 8.5). Samples were hydrodynamically injected into a fused silica capillary at 25.0 mbar for 25.0 s. Separations were performed by applying a voltage of 25.0 kV and a detection at 200.0 nm. To sufficiently reduce BMIMBr adsorption on the interior surface of capillary, an appropriate rinsing procedure by hydrochloric acid and water was optimized. AFILMC measurements of analytes within the concentration range of 0.05-10.0 gmol L-1 achieved adequate reproducibility and accuracy with RSD 1.14-3.42% (n = 15) and recovery 98.0-110.0%, respectively. Limits of detections were 0.71 ng g(-1) AA, 1.06 ng g(-1) AS and 27.02 ng g(-1) GL with linearity ranged between 2.2 and 1800 ng g(-1). The coupling of AFILMC with IL based ultrasonic assisted extraction (ILUAE) was successfully applied to the efficient extraction and determination of AA, AS and GL in bread samples. The structure of ILs has significant effects on the extraction efficiency of analytes. The optimal extraction efficiency (97.8%) was achieved by an aqueous extraction with 4:14 ratio of sample: 3.0 mol L-1 BMIMBr followed by sonication at 35 degrees C. The proposed combination of ILUAE and AFILMC was simple, ecofriendly, reliable and inexpensive to analyze a toxic compound and its precursors in bread which is applicable to food safety. (C) 2015 Elsevier Ltd. All rights reserved.