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Tubes and Accessories
Labware Types
Labware Material Compatibility with Solvents and Sample
The chemical compatibility of tube materials with the gradient-forming medium or other chemicals
in the solution is an important consideration. Although neutral sucrose and salt solutions cause
no problems, alkaline solutions cannot be used in Ultra-Clear or polycarbonate tubes.
Polycarbonate and Ultra-Clear tubes are incompatible with DMSO, sometimes used in the
preparation of sucrose gradients for sedimentation of denatured DNA. Refer to APPENDIX A for
detailed compatibility information.
Gradient Formation and Fractionation
Consideration should be given to gradient formation and fractionation when choosing a tube for a
density gradient run. If the bands or zones formed during centrifugation are indistinct, they may
not be visible through a translucent material such as polypropylene. If optimum band visualization
is important, Ultra-Clear, polycarbonate, or cellulose propionate tubes should be used. Whenever
collection of bands or zones must be done by slicing or puncturing the tube, a thin, flexible tube wall
is required. Ultra-Clear or polypropylene tubes should be used in these cases, depending on the
need for transparency.
Labware Types
NOTE Tubes made of cellulose nitrate were formerly used for various separations, particularly rate-zonal
separations. Beckman Coulter discontinued the use of cellulose nitrate for tube manufacture in 1980, due
to inconsistent physical properties inherent in the material. If you currently have cellulose nitrate tubes,
dispose of them. Consult your laboratory safety officer for proper disposal procedures.
Polypropylene Tubes
Polypropylene tubes are translucent or transparent in appearance, depending on wall thickness,
and are non-wettable (although some polypropylene tubes can be chemically treated to make them
wettable). Polypropylene tubes are reusable unless deformed during centrifugation or autoclaving.
Polypropylene tubes have good tolerance to gradient media, including alkalines. They are
satisfactory for many acids, bases, alcohols, DMSO, and some organic solvents. They can be used
with or without caps in fixed-angle rotors. Speed reduction is sometimes required with these tubes
if run with less than full volume (refer to your rotor manual). Several types of polypropylene tubes
are available.
TLR-IM-9AC
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