FIELD: measurement; testing.SUBSTANCE: invention relates to the identification of chemicals in samples. Method provideschemical transformation and ionisation of a portion of a sample using an analyte detection system. Method comprises introducing a gas into an ionisation source of the analyte detection system via an inlet, generating ions within the ionisation source and directing the gas and generated ions through and out of the ionisation source and to the sample. Sample is located proximal to the ionisation source in an ambient environment. Ions chemically react with the sample, desorb and ionise an analyte from the sample, the analyte being generated from an inorganic oxidiser, the desorbed analyte having a lower melting point and/or better desorption kinetics than the inorganic oxidiser. Desorbed analyte is received by the detection system analyser, such as an ion mobility spectrometer, a mass spectrometer, or a combination thereof.EFFECT: method allows desorption and ionisation of an analyte from surfac
