A method for monitoring a composition of hydrocarbon material extracted from an earth formation is disclosed. The method includes: extracting the hydrocarbon material from the earth formation; diverting a portion of the hydrocarbon material into a container, the container including a pulse neutron spectroscopy tool disposed therein; emitting a plurality of pulses of high-energy neutrons from the pulse neutron spectroscopy tool into the portion of the hydrocarbon material and inducing at least one gamma ray spectrum from the portion; detecting the at least one gamma ray spectrum at the pulse neutron spectroscopy tool; and calculating a composition of the hydrocarbon material based on the at least one gamma ray spectrum. A system for monitoring a composition of hydrocarbon material extracted from an earth formation is also disclosed.