Orthogonal array optimization of ionic liquid based dispersive liquid-liquid microextraction for toxic anilines in foods

A simple and rapid method of ionic liquid based dispersive liquid-liquid microextraction (DLLME) combining with high performance liquid chromatography (HPLC) was developed for the analysis of four toxic anilines in flour steamed bread and maize steamed bread. Several possible influential factors such as the type of ionic liquid and disperser solvent, extraction time, sample pH, ionic strength and the volume of ionic liquid and disperser solvent were optimized using single factor experiments and orthogonal array design (OAD) with OA(25)(5(4)) matrix. Analysis of variance (ANOVA) and percent contribution (PC) were used to investigate the significance of the factors of OAD. Sample pH and ionic strength are statistically demonstrated two chief factors. Under the optimum condition, the method exhibits a good linearity (r(2)>0.99) over the studied range (50-1000 ng g(-1)) for anilines. The extraction factors and recoveries for the anilines in two kinds of steamed breads ranged between 34.1%-73.3% and 44.3%-95.3%, respectively. The limit of detections (LODs) and limit of quantitations (LOQs) ranged between 10-15 ng g(-1) and 30-45 ng g(-1).