Apparatus and method for preparing a ninhydrin reagent

A method for preparing a ninhydrin reagent for use in the analysis of nitrogen-containing compounds comprises irradiating a ninhydrin containing composition with UV light. Preferably, the concentration of the ninhydrin containing composition is from 0.1% to 0.5% w/v. One or more organic solvents may be provided. The UV light may be from a UV source 16 configured to emit wavelengths in the range from 190nm to 430nm, in particular from 350nm to 370nm. The ninhydrin containing composition may be irradiated from 2 to 10 minutes, and at a temperature below 100ºC, such as from 20ºC to 30ºC. An apparatus 2 for preparing a ninhydrin reagent for use in the analysis of nitrogen-containing compounds comprises: a conduit 6 having an inlet 8 for receiving a ninhydrin-containing composition and an outlet 10 for discharging a ninhydrin reagent; and a UV light source for irradiating the ninhydrin-containing composition within the conduit. A method for analysing one or more nitrogen-containing compounds comprises irradiating a ninhydrin-containing composition with UV light in an activation zone (28, fig 2) to produce a ninhydrin reagent; and contacting the ninhydrin reagent with the nitrogen containing compounds in a reaction zone (30, fig 2).