A method for characterization of one or more constituents in a physical sample from electromagnetic spectral information of such physical sample, each constituent consisting of one or combinations of chemical elements and/or their isotopes, molecules and/or their conformations or states, comprising the following steps: • obtaining spectrally resolved electromagnetic spectral information, preferably comprising one or more electromagnetic spectra, corresponding to said physical sample, wherein the electromagnetic spectral information is obtained from a plasma inducing spectroscopy method, • extracting, at sub-optical resolution, at least one spectral line from said electromagnetic spectral information of the sample, • projecting said at least one spectral line into a sample point of a deterministic feature space, defined as a multiple dimension space wherein each dimension of said multiple dimension space is a prediction feature of the at least one constituent in said physical sample to which the electromagnetic spectral information corresponds, said prediction feature providing determination of either the identification or the classification of the at least one constituent in the physical sample and also the quantity of the constituent in said physical sample; said deterministic feature space including a plurality of points each representing a spectral line obtained from a plasma inducing spectroscopy method at sub-optical resolution and each having a predetermined vector basis representative of the spectral line data, the vector basis of each of the plurality of spectral lines: ∘ being stored in a database and having been obtained by sub-optical spectral resolution extraction, and ∘ each corresponding to one of a plurality of known constituents, whereby the projecting of the said at least one spectral line into the sample point of the deterministic feature space, is performed by finding a correspondence between the vector basis of the extracted spectral line and a vector basis of a spectral line already present in the database, and characterizing the at least one constituent in said physical sample from the prediction features corresponding to the location of the projected sample point in the deterministic feature space so as to provide a determination of either the identification or the classification of the constituent and also the quantity of the constituent. • obtaining spectrally resolved electromagnetic spectral information, preferably comprising one or more electromagnetic spectra, corresponding to said physical sample, wherein the electromagnetic spectral information is obtained from a plasma inducing spectroscopy method, • extracting, at sub-optical resolution, at least one spectral line from said electromagnetic spectral information of the sample, • projecting said at least one spectral line into a sample point of a deterministic feature space, defined as a multiple dimension space wherein each dimension of said multiple dimension space is a prediction feature of the at least one constituent in said physical sample to which the electromagnetic spectral information corresponds, said prediction feature providing determination of either the identification or the classification of the at least one constituent in the physical sample and also the quantity of the constituent in said physical sample; said deterministic feature space including a plurality of points each representing a spectral line obtained from a plasma inducing spectroscopy method at sub-optical resolution and each having a predetermined vector basis representative of the spectral line data, the vector basis of each of the plurality of spectral lines: ∘ being stored in a database and having been obtained by sub-optical spectral resolution extraction, and ∘ each corresponding to one of a plurality of known constituents, whereby the projecting of the said at least one spectral line into the sample point of the deterministic feature space, is performed by finding a correspondence between the vector basis of the extracted spectral line and a vector basis of a spectral line already present in the database, and characterizing the at least one constituent in said physical sample from the prediction features corresponding to the location of the projected sample point in the deterministic feature space so as to provide a determination of either the identification or the classification of the constituent and also the quantity of the constituent. ∘ being stored in a database and having been obtained by sub-optical spectral resolution extraction, and ∘ each corresponding to one of a plurality of known constituents, whereby the projecting of the said at least one spectral line into the sample point of the deterministic feature space, is performed by finding a correspondence between the vector basis of the extracted spectral line and a vector basis of a spectral line already present in the database, and characterizing the at least one constituent in said physical sample from the prediction features corresponding to the location of the projected sample point in the deterministic feature space so as to provide a determination of either the identification or the classification of the constituent and also the quantity of the constituent.