Ultrasound-assisted emulsification microextraction coupled with salt-induced demulsification based on solidified floating organic drop prior to HPLC determination of Sudan dyes in chili products

Abstract

This study aimed to analyze the presence of Sudan I–IV in chili products using high performance liquid chromatography and summarized the data performance after ultrasound-assisted emulsification microextraction and salt-induced demulsification with solidified floating organic drop (UAEME-SID-SFOD). After demulsification, the low density solvent was floating instantaneously solidified in an ice-bath; any remaining liquid phase was removed. The solidified part was quickly melted at room temperature and used for analysis. Parameters such as linearity (0.5–2500 ng mL−1, R2 ⩾ 0.999), limits of detection (0.16–0.24 ng mL−1), and limits of quantification (0.53–0.80 ng mL−1) were used to validate this method. The pre-concentration factor for the 5 mL sample solution was 62. Under optimum conditions, the recoveries ranged between 91% and 107%, with relative standard deviations ranging from 1.8% to 3.5% for intra-day (n = 7) and 4.8% to 6.3% for inter-day (n = 5 × 3) analyses. This novel proposed method has great potential applications in most analytical laboratories that use general instrumentation. This method is easy, rapid, and environmentally friendly. In addition, it does not use any disperser solvent and can eliminate the centrifugation step for aqueous and organic phase separation. Therefore, it is expected that the UAEME-SID-SFOD would be a useful method for various analytical sample extraction purposes. Keywords: Ultrasound, Emulsification, Demulsification, Solidified floating organic drop microextraction, Sudan dyes, Chili products