Fluorescent lamps light ageing

Figure 2. Changes in postcolor number of filter-paper sheets with 15% add-on of fractions from thermally aged hemicellulose derived from various pulps. For comparison, the thermal discoloration of a test sheet of groundwood pulp, gp, is shown. The initial postcolor number represents the increase in color over that of the untreated filter paper a, daylight fluorescent lamps b, black-light fluorescent lamps c, heat (90 °C and 50% rh). Key O, blank filter paper , heated BP A, heated GP V, heated...

In the fluorescent UV weathering tester, control of irradiance is simplified by the inherent spectral stabihty of its fluorescent UV lamps. All light sources decline in output as they age. However, unlike most other lamp types, fluorescent lamps experience no shift in spectral power distribution over time. This enhances the reproducibility of test results and is a major advantage of testing with the fluorescent UV weathering tester. 

Spikes in chromatograms can come from many sources, such as aging detector lamps or bubbles in the flow cell both can be easily corrected. External electrical noise sources, such as ovens, refrigerators, cellular telephones, and fluorescent lights, and other possible noise sources such as system electronics or from external electronic sources, and laboratory power feed may be beyond a chromatographer s control. 

---