DETERMINATION OF 12 ELEMENTS IN BOTANICAL SAMPLES WITH INDUCTIVELY COUPLED PLASMA ATOMIC EMISSION-SPECTROMETRY AFTER LEACHING WITH TETRAMETHYLAMMONIUM HYDROXIDE AND ETHYLENEDIAMINETETRAACETIC ACID

The combined use of tetramethylammonium hydroxide (TMAH) and ethylenediaminetetraacetic acid (EDTA) was effective for leaching inorganic constituents from botanical samples for their determination by inductively coupled plasma atomic emission spectrometry (ICP-AES). A powdered sample of 50 mg and 1 ml each of 25% TMAH and 200 mM EDTA were heated for 4 h in a drying oven of 120-degrees-C using a doubly sealed PTFE vessel with a metal jacket. To the suspended solution in a small vessel 2 ml of water were added, the pH was adjusted to 8 and the suspension was centrifuged. The supernatant was used for sequential measurements of major and minor constituents by ICP-AES. The results obtained for some standard reference samples of botanical origin agreed well with the certified or reported values, except for slightly low recoveries of aluminium and iron.