Preparation of beer samples

Samples were prepared following a protocol from a previous stApparatus

SPCE systems, with graphite as working and counter elec- trode and Ag/AgCl as a reference electrode, were manufactured

Washing

V2

Buffer Substrate

Cavro

Waste

XLP 6000

1161

using a DEK 248 screen-printing system according to a proce- dure previously described [26] in a three-electrode configuration.The working electrode was a 4-mm diameter disk, the auxiliary electrode was 16mm x 1.5 mm curved line and the Ag/AgCl pseudo-reference electrode was a 5mmx 1.5 mm straight line.