An apparatus for measuring the fluorescence and light absorbance of a sample, said apparatus comprising: a flow cell for containing a sample, a first UV LED light source, a first light path leading from said first UV LED light source to said flow cell and allowing the propagation of light from the first UV LED light source into the flow cell for irradiating a sample contained therein, a second light path leading from said flow cell to a sample detector and allowing that portion of the irradiating light from the first UV LED light source which is not absorbed by the sample in the flow cell to propagate to said sample detector arranged to determine the amplitude of said portion of the irradiating light, and said apparatus further comprising: a second UV LED light source that emits light with a wavelength of 260-300 nm, and a third light path allowing the propagation of light from the second UV LED light source into the flow cell to further irradiate the sample, wherein the sample detector is further arranged to detect any light resulting from the fluorescence of said sample as a result of said further irradiance wherein one or more of said light paths (5, 7) is in the form of a light conductor and the apparatus yet further comprising: a beam splitter connected to the first UV LED light source via a band pass filter having a wavelength band pass range of 10 nm or less, said beam splitter being for receiving light from the first UV LED light source and splitting it into a first portion and a second portion, wherein the second portion is directed along the first light path, a reference detector arranged to receive the first portion of light and detect electromagnetic radiation therein, and a processing unit arranged to receive a first signal from the reference detector and a second signal from the sample detector and to determine an absorbance of said sample based on said first and second signals (31, 32); and wherein the apparatus further comprises a second additional filter provided between the second UV light source and the flow cell, said second additional filter having a wavelength band pass range of 10 nm. a flow cell for containing a sample, a first UV LED light source, a first light path leading from said first UV LED light source to said flow cell and allowing the propagation of light from the first UV LED light source into the flow cell for irradiating a sample contained therein, a second light path leading from said flow cell to a sample detector and allowing that portion of the irradiating light from the first UV LED light source which is not absorbed by the sample in the flow cell to propagate to said sample detector arranged to determine the amplitude of said portion of the irradiating light, and a second UV LED light source that emits light with a wavelength of 260-300 nm, and a third light path allowing the propagation of light from the second UV LED light source into the flow cell to further irradiate the sample, a beam splitter connected to the first UV LED light source via a band pass filter having a wavelength band pass range of 10 nm or less, said beam splitter being for receiving light from the first UV LED light source and splitting it into a first portion and a second portion, wherein the second portion is directed along the first light path, a reference detector arranged to receive the first portion of light and detect electromagnetic radiation therein, and a processing unit arranged to receive a first signal from the reference detector and a second signal from the sample detector and to determine an absorbance of said sample based on said first and second signals (31, 32); and wherein the apparatus further comprises a second additional filter provided between the second UV light source and the flow cell, said second additional filter having a wavelength band pass range of 10 nm.