A sample plate, portable analysis apparatus and method of analysing sulphur and/or nitrogen compounds in a sample fluid, the method comprising feeding a sample fluid to a sample plate having a sample inlet, a reaction zone, an analysis zone, and at least one separation zone, the sample plate being adapted to allow; (a) a sample fluid to be fed to the sample plate through the inlet to the reaction zone or optionally to a separation zone, which separation zone separates the sample fluid into two or more fractions at least one of which is fed to the reaction zone; (b) a reactant to be fed to the reaction zone; (c) the reaction zone to be maintained under conditions that enable reaction to occur between the reactant and the sample fluid or fraction thereof to produce a product fluid; and (d) transfer of the product fluid to the analysis zone or optionally to a separation zone in which the product fluid is separated into two or more fractions, at least one of which is transferred to the analysis zone.