Thin-film photochemical vapour generation

A process for detecting and/or quantifying an analyte comprising:

• providing a liquid film of a sample containing an organic acid or a salt thereof and a precursor compound of the analyte at a liquid sample support surface of a reaction chamber that has a liquid sample inlet, a carrier gas inlet, and carrier gas outlet;
• exposing the liquid film to ultraviolet radiation to generate a volatile species of the analyte by providing an ultraviolet source comprising an ultraviolet lamp or an ultraviolet LED, and the ultraviolet source further comprising either a coil that surrounds the reaction chamber and the liquid sample support surface, or straight discharge tubes configured around the reaction chamber and the liquid sample support surface and extending a length of the reaction chamber;
• separating the volatile species from the liquid film to form a vapour containing the volatile species;
• and,
• directing the vapour to a detector to detect and/or quantify the analyte in the vapour.

A photochemical vapour generator comprising:

• a reaction chamber having a liquid sample inlet, a carrier gas inlet and a carrier gas outlet;
• a liquid sample support surface for supporting a film of a liquid sample in the reaction chamber wherein the liquid sample support surface is a surface of a quartz rod that is separate from, and housed within, the reaction chamber;
• and,
• a source of ultraviolet radiation positioned in radiative contact with the liquid sample support surface.