The Atmospheric Solids Analysis Probe* (ASAP) (introduced by McEwan et al) is a useful tool for the rapid direct analysis of volatile and semi-volatile, solid and liquid samples using atmospheric pressure ionization.
The ASAP technique utilizes the heated nitrogen desolvation gas to vaporize the sample and a corona discharge for sample ionization. This allows low polarity compounds not amenable to ESI, APcI and APPI to be ionized with a high degree of sensitivity. Furthermore complex mixtures can be analyzed without the need for any sample preparation.