The final yield of an oligo is determined by measuring the OD (Optical Density) values. One OD260 unit of DNA is the amount of DNA that gives an absorbance reading of 1.0 at a wavelength of 260 nm, for a sample dissolved in 1.0 ml total volume of ddH20 which is read in a 1 cm quartz cuvette. 1 OD260 corresponds to approx. 33 µg/ml of single stranded DNA, depending on the GC content.
To ensure the identity and qualitative purity of each and every synthesised oligonucleotide, we use the latest generation of Sequenom MALDI-TOF (Matrix Assisted Laser Desorption Ionisation - Time of Flight) mass spectrometers. The high grade of automation and the use of proprietary software to analyse the spectra ensures that we deliver oligonucleotides of highest quality.
Capillary Gel Electrophoresis (CGE)
CGE is an effective method for checking the quantitative purity of the synthesised oligonucleotides. It is performed routinely on unmodified oligonucleotides >60 bases which have been purified by RP-HPLC or HYPUR. The electropherograms can be provided along with the synthesis report as quality documentation.