Analysis of forchlorfenuron and thidiazuron in fruits and vegetables by surface-enhanced Raman spectroscopy after selective solid-phase extraction with modified [beta]-cyclodextrin

[beta]-Cyclodextrin and its derivatives can selectively bind to various organic molecules in its cavity and provide good applications in sample preparation. Surface-enhanced Raman spectroscopy is a sensitive technique and has received increasing attention in the last decade. Herein, 3,5-dimethyl phenyl carbamoylated [beta]-cyclodextrin bonded silica gel was used as a ssorbent in solid-phase extraction to selectively enrich forchlorfenuron and thidiazuron followed by determination with surface-enhanced Raman spectroscopy. It showed excellent selectivity for forchlorfenuron and thidiazuron and the adsorption capacities were 40.0 and 30.0 µg/g, respectively. A rapid and sensitive method based on the modified [beta]-cyclodextrin solid-phase extraction coupled with surface-enhanced Raman spectroscopy was developed. The linear ranges were 30.0-300.0 µg/L for forchlorfenuron and thidiazuron at 1005 and 640 cm-1, respectively. Both of the limits of detection were 15.0 µg/L, which were significantly lower than the maximum permitted by the National Standard. The recoveries of forchlorfenuron and thidiazuron were 78.9-87.9% for the spiked grape, kiwi, cucumber and tomato, with relative standard deviations of 8.1-13.2%. The results show that this method is sensitive, selective, and relatively time saving, and has great potential in the analysis of trace amounts of plant growth regulators in fruits and vegetables.