METHOD OF DETECTING ORGANIC MOLECULES Russian patent published in 2009 - IPC G01N27/62 G01N30/64 

FIELD: chemistry.

SUBSTANCE: present invention pertains to gas analysis and can be used for detecting vapours of organic compounds in air. The said method involves recording peaks of ion current on drift-spectra of ions of organic molecules, that is, the relationship between ion collector current I_c and compensation voltage U_c, at different values of amplitude of output voltage of a high-voltage generator. The position of U_c.max of maximum peaks of ion current I_c.max on the compensation voltage scale is determined using the drift-spectrometer of ion mobility, containing series-arranged, in the direction of pumping air through the spectrometer, a device for ionising the probe of organic molecules in air, a device for separating the formed ions on parametres of the linear part of the drift mobility of ions and a device for recording ion current, which comprises at least, an ion collector. One of the electrodes of the device for separating ions is connected to a high-voltage generator with alternating, periodically assymetrical polarity of voltage and a low-voltage source of compensation voltage. A surface-ionisation ion source of organic molecules is used to ionise the sample. Constants ΔU₀, A and B are predetermined for the device calibration relationship between ΔU=ΔU₀+AI_c.max+BU_c.max of the half-width of peaks ΔU of ion current on drift-spectra on half their height with the maximum peak of ion current I_c.max, and the position of the peak U_c.max on the drift-spectrum. After that the drift-spectra of organic molecules are recorded. Taking into account device calibration characteristics, peaks of ion current on the drift-spectrum are separated, and for each, the true position of U_c.max on the scale of compensation voltage is determined.

EFFECT: more accurate detection of organic compounds, through more accurate determination of the position of maximums of peaks of ion current on drift-spectra.

3 cl, 4 dwg