Sensitive determination of trace-metal elements in tea with capillary electrophoresis by using chelating agent 4-(2-pyridylazo) resorcinol (PAR)

A capillary electrophoresis method was developed for the determination of trace metals (Cu, Fe, Zn, Co and Ni) in tea based on the conversions of strong complexes between 4-(2-pyridylazo) resorcinol (PAR) and metals. Five metals can be determined in 10 min by a single run. The calibration curves showed a linear range from 50 μg/l to 5 mg/l for these metals with correlation coefficients (r2) being greater than 0.999. Detection limits (S/N=3) of Co, Fe, Cu, Zn and Ni varied from 6 to 30 μg/l. Recoveries of these metal ions ranged from 97.9 to 106.2%. The method is simple and separation time is short.