One of the modern problems, arising in the detection and identification of substances, is a development of criteria for
the assessment of a presence of explosive (or other dangerous substance) fingerprints in investigating THz signals
reflected from a sample. Obviously, criteria depend on using method for the detection and identification of the
substance. Taking into account on our previous experience, we use for a solution of this problem the SDA method
(method of the spectral dynamics analysis). In this case, we need, at least, developing the method for both getting
requiring dynamics of spectral lines and assessment criteria and their algorithmic realization.
In this paper, we show that the SDA method allows to identify the explosive under real conditions. We compare the
spectral lines dynamics of THz pulse reflected from sample with the corresponding spectral lines dynamics of the THz
pulse transmitted through the explosive. Used assessment and algorithm show both high probability of the substance
identification and a reliability of realization in practice. Simultaneously, we discuss some problems connected with the
main problem of the paper. It should be stressed that we use reference-free method for the detection of explosive. As
one was emphasized in our previous papers, we do not use the main reflected pulse for the substance detection because
it contains only information about the dielectric permittivity of material and does not contain the information about
absorption properties of substance at using the reflection mode of THz device.