Time-of-flight mass spectrometry analysis of biomolecules

A time-of-flight mass spectrometer for measuring the mass-to-charge ratio of ions generated from a sample, the spectrometer comprising:

• (a) a sample holder adapted to provide a source of sample molecules from a liquid or solid sample;
• (b) an laser adapted to generate a pulse of energy and arranged to ionize with the pulse of energy the sample molecules provided by the sample holder to form sample ions;
• (c) a first element spaced apart from the sample holder and disposed between the sampler holder and a second element spaced apart from the first element;
• (d) an electrostatic lens spaced apart from and disposed between the second element and a drift tube;
• and
• (e) a power source electrically coupled to the sample holder, the first element and the second element and arranged to apply:
• (i) a first variable potential to the sample holder, a second variable potential to the first element and a third variable potential to the second element to establish and a sample ion retardation electric field at a first predetermined time subsequent to the generation of a pulse of energy by the laser, and
• (ii) a fourth variable potential to at least one of the sample holder, the first element and the second element to establish a sample ion extraction electric field at a second predetermined time subsequent to application of the first, second and third variable potentials;
• wherein the drift tube is arranged to receive sample ions extracted by the sample ion extraction electric field.