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PostPosted: July 9th, 2012, 4:58 pm 

Joined: February 13th, 2011, 12:32 am
Posts: 82
Arson Investigation (using UV 365nm LED Light)
Accelerant residues will fluoresce when exposed to 365nm UV light, even after the odors of accelerants are gone. The fluorescence is affected by heat exposure. The longer an accelerant is exposed to heat, the more differentiated its fluorescence color will be from other less exposed areas. This can assists in locating the point of origin of the fire.

Volatile hydrocarbons such as gasoline, kerosene fluoresce when exposed to UV short wavelength (less than 300nm).

Water Testing of Escherichia Coli (using UV 365nm LED Light)
A lot of airborne pollutants fluoresce in the 250-400nm wavelength range. The poisoning associated Escherichia coli (E. Coli) will also fluoresce in this range.

The test to identify E. coli is performed in test tubes filled with indicator nutrient dissolved in sample water. The solution is colorless. Tubes are then placed in 35oC incubator for 24 hours. If the solution turns yellow, coli forms exist in the water sample. If those tubes fluorescence under a UV 365 LED light, E. coli exists in water sample.

Milkstone Testing (using UV 365nm LED Light)
Some proteins found in milk and yogurts fluoresce when illuminated with UV 365nm light. Fresh deposits fluoresce yellow-white. If chemicals used to clean the deposits are not effective and left milkstone behind, it will fluoresce blue-white. The most common places for milkstone buildup are roughened areas, such as agitator blades, welded seams, corners of valves, and valve junctions.

Other notes:
1. To distinguish between milkstone fluorescence and reflection from stainless steel, you can move the light back and forth from the suspected fluorescent surface. Brightness will change if it is reflection;
2. Grease used on various valves and connections also fluoresces, but can be wiped off.

Aflatoxin Testing ( using UV 365nm LED Light)
Aflatoxin can be detected by using UV 365nm LED light. Aflatoxin is metabolites produced by the mold Aspergillus flavus on various grains and nuts. Aspergillus flavus can occur on all grains, fruits and vegetables if they are stored in damp places at temperatures that permit the growth of the mold and subsequent aflatoxin formation. Insect damage was found to be related to the presence of aflatoxin in pre-harvest corn.

AFLATOXIN are separable into Aflatoxins B1, B2, G1, M1, B2a and 4G2a. They all have absorption maxima around 360nm. The B toxins fluoresce at 425nm and the G toxins fluoresce at 450nm. The B1 toxin is the most common, followed by B2 toxin. The G toxins are fairly rare. The fluorescence sensitivity of the G toxins is more than 10 times greater than that for the B toxins.

Other notes:
1. Many other fungi and other species which do not produce aflatoxin may fluoresce.
2. Brightly fluorescing samples may contain less aflatoxin than weakly fluorescing samples,
3. Test samples need to be fresh because the fluorescence will eventually disappear, although the toxin itself remains.

Thin-layer Chromatography (TLC) using UV 365nm LED Light
365nm UV LED Light can be used with Cellulose coated TLC plate to compare the composition and concentrations of known and unknown samples.

TLC is done on a TLC plate consisting of a solid support (glass, plastic or aluminum) coated with a thin layer of absorbent material such as cellulose. Known and unknown samples are deposited and migrated with solvent along the cellulose. After solvent is dried, the dissolved compounds will be left on the cellulose. The TLC plate is then sprayed with developer and observed under UV-365 light, unknown compounds are considered to be identical to known standard if they migrate similar distances and exhibit the same degree of fluorescence (meaning similar concentrations.)

Reflected UV Photography
A UV 365nm LED light source is directed at the subject, which will then reflect this radiation back into the camera. The subject may be excited to emit fluorescence in the visible spectrum. The UV transmission filter over the lens will prevent any visible radiation from impinging on the film.

UV induced fluorescence photography
A UV 365nm LED light is aimed at the subject in a completely darkened room (daylight may wash the fluorescent). The subject reflects the UV and may also emit a visible fluorescence. The UV reflection is prevented from entering the lens by an UV absorbing filter. The film records any visible fluorescence

PostPosted: July 29th, 2012, 3:49 pm 

Joined: July 29th, 2012, 3:03 pm
Posts: 2
The 365nmLED lights in wide-ranging applications for adhesive and paint curing, sterilization, skin treatment, forensics particle detection, currency verification, fluorescence, blacklight blue,in film making, camera etc.

Caution: UV LED lights when in any operation emit invisible ultraviolet radiation, that may be harmful to eyes or skin, even for briefing periods. Do NOT look directly into the UV LED lights during any operation. Should be sure that you and all persons in the vicinity wear adequate UV Safety protection for eyes and skin. If any one incorporate a UV LED lights into a product, be sure to provide WARNING labels.

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