Biochrom Ultrospec 3100 pro Spectrophotometer


  • UV and visible spectrophotometer (wavelength range: 190-900nm)
  • Stored protocols for protein determination (Bradford, Biuret, Lowry and BCA) and nucleic acid quantification/characterisation (DNA, RNA, oligonucleotide, theoretical Tm calculation)
  • Accommodates 50 user-stored methods
  • Built-in applications software for wavelength scanning, enzyme kinetics, standard curve, substrate concentration and multi wavelength equation entry
  • 8-position sample changer
  • Bandwidth: 3nm
  • Absorbance range: -3.000 to 3.000

Use of the machine in the Molecular Biology Facility

Many researchers use this spectrophotometer for highly sensitive analysis of nucleic acid samples. Small volumes (as low as 50µl) can be accommodated by using small volume UV transparent disposable cuvettes (UVette 220 from Ependorf, 0030 106.300) and the supplied adaptor for raising the sample into the light path

Tips and Additional Information

A solution of DNA or RNA with an optical density of 1.0 at 260nm has a concentration of 50 or 40µg/ml, respectively. This is taken into account (factor) to calculate concentration in the nucleic acid modes

In DNA or RNA mode, the machine will automatically measure absorbance at 260nm and 280nm. Pure DNA and RNA will give an expected 260:280nm ratio of 1.8 and 2.0, respectively. Any cross contamination from protein will result in a reduced 260:280 ratio. If the ratio is very low, the sample should be purified by phenol-chloroform extraction and ethanol precipitation

The sample changer will automatically change to the next sample unless you set the machine as a single cell holder. Press 'function' and select 'treat as a single cell holder' by putting a tick in the box (use the across arrows)

The machine is also used for spectrophotometric readings of protein assays. If you wish to perform your protein assays in a microtitre plate, use the PolarStar Galaxy microplate reader in N445, Anderson Stuart Building