We want to eliminate potential contamination of plastic tubes and large pipette tips (5 mL). Will UV radiation disinfect the interior of the tubes and tips, passing through the plastic walls? Most of the technical literature suggests that line-of-sight radiation of a surface is desirable. This raises the question of whether we are really disinfecting the whole tube/tip, or just the outer surface. Thanks.
we have a paper that will be published in the next issue of World Aquaculture Magazine on graduate education in aquaculture. Not sure that is what you are looking for, but I am not aware tech transfer studies. You might check with Sea Grant offices, they collect metrics on such things.
This depends on the material, wall thickness, planned exposition time and UV wavelength used for disinfection. Most plastic material is not UV-transparent, in this cases the inner side will not be reached by UV radiation.
Teflon is probably your best bet, spectra are here-
http://engineering.case.edu/centers/sdle/sites/engineering.case.edu.centers.sdle/files/optical_properties_of_teflon_r_af_amorphous_fluo.pdf
Stay clear of plastics such as polystyrene with aromatic side groups that absorb strongly in U.V.
As can be seen from this Wiki entry, UV disinfection is most effective for UV wavelength around 250nm (https://en.wikipedia.org/wiki/Ultraviolet_germicidal_irradiation ).
As can be seen from this link (http://www.biotek.com/resources/articles/absorbance-measurement-ultraviolet-spectrum.html), most labware plastics has sufficient transmittance for wavelengths greater than 300nm, but not neccessarily below 300nm.
Best thing would be if you do an absorbance scan for the material you want to disinfect, then you can easily decide about the feasibiltiy of UV disinfection for the respective labware. Be aware of coloured pipette tips, the included dye might well prevent UV transmittance, even if the basic material would work... So, go on and find out yourself with a UV/VIS spectrometer, you might well be able to produce yoru own sterile labware and save a lot of money:-) (Suppliers will hate me for this...)
Of course you should validate your method for effectiveness, once established.
Your disinfection lamps are almost certainly un-coated mercury vapor lamps, which emit at 254nm, which is close to the DNA/RNA absorbance peak of ~265nm, which is why that lamp is the dominant emitter for disinfection applications.
As mentioned by others, most plastics are not transparent at 254nm. As Mr. Wells notes, Teflon is one exception. A 1mm thick piece of Teflon will transmit roughly half of the incident 254nm radiation, and will not be degraded by the UV (unlike other plastics).
Another suited material would be COP/ COC (cycloolefine (co-)polymere). However, the question is about finding a way for making standard plastic labware sterile... You'll hardly find any pipette tips or tubes made from Teflon. And if they exist, they'll be more expensive than buying sterile grade standard labware.
Teflon pipette tips are available, at least in small sizes, but are probably expensive. As Mr. Menges points out, it would likely be cheaper to use sterile, disposable tips. Depending on the plastic, would autoclaving be an option?
For tubing, Teflon tubing is readily available, but is pretty stiff. THV tubing is also quite transparent to UVC, and is flexible, but it won't withstand heat (you can't autoclave it).
I don't have shares in any Teflon companies, but maybe the fact Teflon is "non-stick" will also reduce possibility of contamination ?
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