Direct nanogram quantitation of nucleic acid and protein with a continuous-flow microcell

A simple method for rapid nanogram measurement of nucleic acids and proteins is described. It requires only 5 to 10 microliter of sample solution which is injected into the postcolumn flow stream of a high-performance liquid chromatograph. Samples are analyzed by uv detection at 260 nm for nucleic acids and 280 nm for proteins with a diode array detector. Analyzing speed is two samples per minute and the amount to be analyzed ranges from 3 ng to 80 micrograms for nucleic acids and 10 ng to 80 micrograms for bovine serum albumin, irrespective of the sample volume. The method is particularly useful for fast, accurate, and trace amount measurement of purified DNA, RNA, and protein samples in small volumes.