Abstract:

In order to probe into the distribution characteristics of fluorine content in wolfberry fruits at different growth stages, green, yellow and red wolfberry fruits from the same cluster wildly growing in the east suburb of Zhengzhou were extracted with 1.0 mol/L HCl under ultrasonic assistance and the concentrations of micro fluorine in the extracts were directly given by fluorine ion selective electrode. It was showed that wolfberry fruits exhibited a gradual increase in moisture content during ripening, whereas fluorine content had an opposite change. The content of fluorine was 0.68μg/g in green wolfberry fruits, 0.57 μg/g in yellow wolfberry fruits and 0.53 μg/g in red wolfberry fruits. All the relative standard deviations (RSDs) of precision for 5 replicate determinations of green, yellow and red wolfberry fruits were smaller than 3%. The method spike recovery range was between 97.0% and 105.0%. Thanks to the merits of simplicity, rapidity and good practicality, this method deserves to be popularized.

Key words: wolfberry fruits, micro fluorine, ultrasonic-assisted extraction, direct reading concentration method, distribution characteristics