There isn't written nothing about phosphine gas, but more interesting is this B2 tag (I guess category of this filter). This filter is used for chlorine gas.
the filter is effective against inorganic gases and vapors - chlorine, fluorine, hydrogen cyanide, hydrogen sulphide, cyanide chloride, etc. the filter is not effective against carbon monoxide, nitrous oxide, methane, ethane, propane, etc. the rest is not important