2.8. Digestion of the samples
The wet-ashing microwave-assisted method was
employed for the digestion procedure described below.
From 0.4 to 0.45 g of the powdered plant samples were
weighed into the Teflon PFA vessels and treated with 5
ml (2:1) of 69.4% w/w HNO3 and 70.0% w/w HCIO4.
The vessels was covered with a lid and screw cap; the
contents of each vessel were arranged in the turntable
and put into the microwave oven for digestion in a preselected
programme (one stage at 0% for 5 s; two stages