Immobilization of zeolitic imidazolate frameworks with assist of electrodeposited zinc oxide layer and application in online solid-phase microextraction of Sudan dyes.

Herein a facile method for immobilization of zeolitic imidazolate frameworks (ZIFs) was developed. The ZIFs grew on electrochemically deposited zinc oxide (ZnO) layer while carbon fiber bundle served as substrate. The synthesized ZIFs-ZnO composite was packed into PEEK tube as sorbent for online solid phase microextraction (SPME)-HPLC-UV analysis of Sudan dyes. Good enrichment efficiency (200-461 fold), low limits of detection (0.002 ng mL-1) and wide linear ranges (0.02-20 ng mL-1, correlation coefficient > 0.9996) were achieved. The analytical method was demonstrated to be practical for analysis of Sudan dyes in environmental water samples with good recoveries (83.5%~95.0%).