MPI-1 can be ascertained utilizing peak of phenanthrene and methylphenanthrenes from gas chromatograms or then again m/z 178 and 182 mass chromatograms, separately. Computation of MPI-1 from mass chromatograms requires reaction factors that are best decided by the expert. Then again, Cassani et al. (1988) altered the MPI-1 figuring for peak estimated from m/z 178 and 192 mass chromatograms as pursues:
MPI-1 = 1.89(2-MP + 3-MP)/ [P + 1.26(1-MP + 9-MP)] where MP is methylphenanthrene and P is phenanthrene. A comparative development file was utilized by Alexander et al. (1986b) and modified by Cassani et al. (1988):
PP-1 = 1-MP/(2-MP + 3-MP)
PP-1modified = (1-MP + 9-MP)/(2-MP + 3-MP)
A few difficulties influence the utilization of methylphenanthrene Index:
_ Samples of various maturity can demonstrate the same methylphenanthrene index ratio.
_ Variations in the sort of natural issue or lithology in the source shake can influence methylphenanthrene ratio. For instance, Cassani et al. (1988) noticed that high MPI-1 and PP-1 compare to high carbonate content in La Luna source rocks. Movement may additionally influence different sweet-smelling hydrocarbon proportions (Radke et al., 1982b).