Abstract:

A rapid method using ion selective electrode was established for the determination of trace fluorine in soybean. The procedure was based on extraction of test portions with 1.0 mol/L HCl solution in an ultrasonic field and addition of standard fluorine solution followed by direct reading of fluorine concentration. The average fluorine contents in two samples of soybean tested were 3.42 and 3.050 μg/g respectively, with a RSD less than 3.0% (n = 5), and the relative error was －1.25% in comparison with the determination results of the standard solution. This method is simple, fast and practicable, and can meet the requirements for in situ determination of large quantities of complex matrix samples without plotting and complex calculation.

Key words: soybean, ultrasonic extraction, trace fluorine, standard addition-concentration direct-reading method, rapid determination