Ambient mass spectrometry in the analysis of compounds of low polarity

Ambient mass spectrometry techniques that are capable of ionizing compounds of low polarity are discussed. Photoionization and plasma-based ionization are the most important ionization techniques, but in some special cases modification of electrospray-based techniques can also result in improved ionization efficiency for low polarity compounds. The most important technical setups are presented together with examples of key applications in the fields of biology, environment, food and forensics.