The cause of the higher rate for 4-nitrotoluene might be due to the possession of a distinctive functional group.
Shikha Rai, Awadhesh Kumar Rai 2011, 'Characterization of organic materials by LIBS for exploration of correlation betweenmolecular and elemental LIBS signals', AIP Advanceshttp://dx.doi.org/10.1063/1.3650860. Retrieved from DOAJ CC BY 4.0 (https://creativecommons.org/licenses/by-sa/4.0/legalcode)