Phase diagram can be constructed that show the effect of more than two variables on the phase of a substance. Phase diagrams can use other variables in addition to or in place of temperature, pressure and composition, for example the strength of an applied electrical or magnetic field, and they can also involve substances that take on more than just three states of matter. One type of phase diagram plots temperature against the relative concentrations of two substances in a mixture called a "binary phase diagram", as shown at right. Such a mixture can be either a solid solution, eutectic or peritectic,
Phomoxanthone A PXA and PXB were discovered in 2001, and their preparation by isolation from "Phomopsis" fungal cultures was described in the corresponding publication. Briefly, a MeOH extract of a "Phomopsis" culture is mixed with HO and washed with hexane. The aqueous phase is then dried and the residue is dissolved in EtOAc, washed with HO, concentrated and repeatedly purified by size-exclusion chromatography. The resulting mixture of PXA and PXB is separated by HPLC. A modified method, in which the initial extraction is done with EtOAc instead of MeOH and the drying step is skipped, was described in 2013. Phomoxanthone A was