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(NH3)(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-standed DNA.