Measurement of DNA in cultured human cells

A simple microtechnique has been developed for the accurate determination of DNA in less than 1 × 10⁶ cultured human fibroblasts or lymphoblasts. This technique involves rapid separation of DNA from the cell extract supernatant and from the extraction buffer in order to avoid interference with the colorimetric diphenylamine assay. The method described does not involve complicated manipulation of samples and does not require special instrumentation. In addition, multiple samples can be conveniently prepared to be assayed at a later time and various other biochemical determinations such as enzyme assays can be done on soluble extracts of the same cell samples.