On-line sample digestion using an electromagnetic heating column for the determination of zinc and manganese in tea leaf by flame atomic absorption spectrometry

A new on-line sample digestion system using electromagnetic induction heating technique was developed for the determination of zinc and manganese in tea leaf by flame atomic absorption spectrometry (FAAS). The homemade electromagnetic heating column (EMHC), whose effective diameter was about 1 mm, was composed of a polytetrafluoroethylene (PTFE) outer tube and seven compactly packed PTFE coil-coated iron wires. The pre-digested sample solution was pumped through EMHC and then transferred directly to FAAS for determination. An analytical throughput of 72 samples h−1 was obtained in the present system. Under optimal condition, the detection limits (3σ) of zinc and manganese were 4.2 μg L−1 and 3.0 μg L−1, along with relative standard deviations (R.S.D.) of 3.2% and 3.6% respectively for zinc and manganese. Certified reference materials GBW 07602, GBW 07605 and GBW 08505 were analyzed to validate the proposed method, good agreement was achieved between the certified values and the obtained results.