Determination of traces of RNA in submicrogram amounts of single‐ or double‐stranded DNAs by means of nucleic acid‐modified electrodes

Recently we have utilized the advantages of nucleic acid‐modified mercury electrodes to develop a method capable of determining RNA traces in samples of double‐stranded DNA [1]. It was, however, impossible to determine less than 10 % of RNA in a single‐stranded DNA sample. Here we show that the DNA voltammetric signals can be selectively suppressed by precipitation with [Co(NH 3 ) 6 ] 3 + while the signal of any RNA digested with RNase A is not influenced. Following from our studies we proposed a voltammetric method for determination of less than 1% of RNA in microgram samples of single‐ and double‐stranded DNA.