Introduction:
Different mixtures of similarly colored detergent must be shuttled along a conveyor line, presumably in a manufacturing application. As detergents display fluorescence wavelengths similar to those emitted by the light source near 365nm, it was necessary to determine whether differences in the fluorescence of such detergents could be identified using the reflection probe. By measuring samples of distinct detergent mixtures with the probe in combination with a lowpass UV filter, it was determined that the fluorescence of the detergent was not only distinguishable from the light source, but distinguishable from every other sample as well.

Hardware Used:
USB2000-USB2E4066, grating 1, 200 micron slit, L2 lens
PX2 Light Source
R600-7-SR/125F Probe
LVF – FHS
P1000-2-UV/Vis Fiber
UV-LVF-Lowpass-300nm

Measurement Mode:
Relative Irradiance

Experimental Conditions:
Samples of detergent were individually placed in plastic weighboats, approximately 1cm below the reflection probe. The probe was suspended from a clamp, and shielded with dark cloth to minimize outside light interference. In order to block wavelengths of light from the source suspected to coincide with the wavelength of fluorescence, a UV-LVF lowpass filter was placed in between the light source and fiber at around 300 nm. A P1000 UV/Vis fiber in conjunction with an LVF-FHS was used in order to gather more light. Measurements were then taken, replacing the sample each time.

Results:
Using relative irradiance mode, fluorescence peaks of gradually increasing intensity were observed at approximately 406nm, 422nm, and 426 nm depending on each sample. Peaks were also observed below 300nm, and above 590nm, but this was a result of the emissions from the light source outside the range of the lowpass filter. The resulting fluorescence peaks were different than the estimated value of 365 nm. These fluorescence peaks corresponded to the wavelength of light emitted by the detergent when excited by the PX-2 light source as indicated in figure 1 below. Figure 2 is a close up of fluoresced emission.

Conclusions:
Based on the resulting data, it can be concluded that the reflectance probe compounded with a lowpass filter is an appropriate apparatus for determining the fluorescence of detergent samples.