The obtained packing (microcolumn)was rinsed with methanol with
intermittent (4–5 s) application of pumping pressure (~2 bars)
to improve the compactness of the packing. The packings were conditioned
with 10 min washing with methanol and 5 min with the mobile
phase before the chromatographic separation/preconcentration.A schematic
depiction of the packing preparation procedure and the picture of
the obtained microchip are given in Fig. 1a,b.