Figure 1: Showing an XPS spectra of a) a sample (BS002) which has no fingerprint, and has been cleaned in micro 90 before being placed in the XPS, and b) a sample (BS009) which has had an eccrine fingerprint applied, and has been left in air for ~15 hours before being placed in the XPS.

One can see a distinct lack of Cu peaks in the latter spectrum, as well as an increase in the C 1s peak, and maybe even a potential Na 1s peak.

Figure 2: Showing various XPS sectra of a) a sample (BS002) which has no fingerprint, and has been cleaned in micro 90 before being placed in the XPS, b) a sample (BS009) which has had an eccrine fingerprint applied, and has been left in air for ~15 hours before being placed in the XPS, c) the same sample as b) left in air for a further ~ 17 hours, (~39 hours since fingerprint application), and d) a sample (BS011) which has had an eccrine fingerprint applied at the same time as the sample in b) and c), only has been left in air for ~65 hours (nearly 3 days) before taking the spectra.