Before opening any bottle of sediment, it was
manually shaken for 5 min to rehomogenise the contents.
Samples were taken with a plastic spatula.
The extraction was performed in 100 ml, precleaned
borosilicate glass, PTFE or polypropylene
centrifuge tubes using an end-over-end mechanical
shaker operating at 30 rpm, in a room at 20 28C.
The temperature of the room was measured at the start
and at the end of the extraction procedures. The
sequential extraction procedure is described below: