Based on advantage of cyclic neutron activation of 20F(t1/2=11.03 s)

cyclic neutron activation analysis(CNAA) and three traditional methods

i.e.UV-vis spectroscopy

fluorine ion selective electrode

and chromatography of ions

were used to determine fluorine concentration in standard reference materials of tea(GBW10016).Compared with the three traditional methods

CNAA is accurate

sensitive

time-saving

little sample amount

strong traceability and good anti-interference.Fluorine concentrations in 16 commercial teas of four categories were determined by using CNAA.The results showed that fluorine concentrations of brick tea

black tea

oolong tea and green tea are 60 276

54 66

37 59 and 34 49 mg/kg

respectively.It was also found that the fluorine concentrations in different tea categories are likely attributed to their raw materials and production process.Fluoride concentration in one tea product was 276 mg/kg

while the national standard is ≤200 mg/kg.