Embodiments generally relate to detection of end of service life for respirator filter cartridges for organic vapor(s). Typically, detection of end of service life might use a competitive UV absorbance-fluorescence approach. Thus, a sensor that emits light upon application of UV may be placed within the cartridge, with a UV lamp and a light detector directed at the sensor. In some embodiments, a plurality of corresponding sensor and UV lamp and light detector might be used. Typically, the light level emitted by the sensor(s) might be used to estimate effective end of service life.