compounds is given in a Supplementary Table. These were used to
determine the cross-sensitivities of the WOLF sensors to these
chemical standards. The 5 mL samples were heated to 4070.1 °C
for 5 min in order to build up headspace and the injected into the
WOLF. The sample headspace flowed into the WOLF for 5 min and
then replaced with clean air (repeated 3 times). The sequence of
solution concentrations tested was randomised to mitigate the
chances that a long-term response drift would allow for fabrica-
tion of response change with increasing concentration.