DNA和RNA的检测

Ultraviolet (UV) measurements in microplates became possible 5 years ago when Molecular Devices introduced the first UV–capable microplate spectrophotometer and UV–transparent microplates. Since then, microplate measurements of DNA,RNA and proteins have become very popular. However, microplate assays require awareness of the optical properties of the microplate materials and more attention to technique than do traditional cuvettes in order to get accurate absorbance results, especially in the UV range. Lack of attention to these details is the most frequent cause of difficulty in adapting assays to microplates. Absorbance measurements made through microplates are subject to pathlength variability and are vulnerable to interference from surface effects at the air/liquid interface (Maxline App. Note #32). Modern microplate spectrophotometers, with smaller optical beams than older wide–beam plate readers, are much more vulnerable to spurious readings due to dust. Particles in the light beam at the time of a read can cause artifactual absorbance spikes of up to 0.3 OD. Therefore it is especially important that sample solutions be free of particles. All of the above factors must be kept in mind in order to get accurate and reproducible absorbance results in microplates. The purpose of this Application Note is to provide guidelines for optimizing DNA/RNA absorbance measurements in SPECTRAmax microplate spectrophotometers.