Why not try the easy to use Quant-it kits from invitrogen which uses a
fluorescent dye and can be used in a microplate as well as a cuvette
format (Q33210). Even easier use the cheap new Qubit fluorometer
(Q32857, approx £350), which uses LED light technology, with the Qubit
Protein Quant-it kit (Q33211, £35)--life is too short to be messing
about with Bradford & Lowry assays these days. The kit each contains a
proprietary fluorescent dye, which binds specifically to proteins.
When in aqueous solution the dye emits a low fluorescence signal that
increases on binding.
All the Quant-it kits (including ones for ssDNA, dsDNA & RNA) are
compatible with reducing reagents and the presence of a wide range of
contaminants, which are listed in the back of their respective kit
manuals. The sensitivity, including the DNA/RNA kits, used with the
Qubit device are
Kit Assay range Sample
Quant-iT DNA HS Assay 0.2 - 100 ng 10 pg/mL - 100 ng/mL
Quant-iT DNA BR Assay 2 - 1000 ng 100 pg/mL - 1 mg/mL
Quant-iT RNA Assay 5 - 100 ng 250 pg/mL
- 100 ng/mL
Quant-iT Protein Assay* 0.25 - 5 mg 12.5 ug/mL - 5 mg/mL
If detergents are present, the bane of most protein assays, use the EZQ
Protein Quantitation kit R33200 which is adapted into microplate format
and involves a binding the protein to a membrane and washing to remove
contaminants, easier than it sounds.