FIG. A2.

Effect of different acetaldehyde concentrations on the colorimetric diphenylamine assay for DNA. (a) Assays with DNA (filled symbols) and without DNA (open symbols; blanks). (b) Differences of assay values, with DNA minus blank. The graph shows that acetaldehyde alone reacts with the diphenylamine without reaching a plateau, whereas the reaction with DNA is complete in 5 to 10 h and independent of the acetaldehyde concentration in the range tested. Blk., blank; nucleot., nucleotides; acetald., acetaldehyde.