Application of aluminium(III) complex with salicylidene-o-aminophenol to the fluorometric determination of nucleic acids

In buffer medium of hexamethylene tetraamine-HCl at pH 5.9 the aluminium(II I) complex with salicylidene-o-aminophenol (SAP) has a fluorescence peak at 508 nm with excitation at 410 nm. When nucleic acid coexists, it reacts wi th the complex within 8 min at room temperature to produce a non-fluorescen t product, resulting in the decrease of fluorescence intensity of the alumi nium complex. On basis of this, a new fluorometric method for nucleic acids determination is proposed. The calibration graphs for calf thymus DNA, fis h sperm DNA and yeast RNA are linear up to 5.0, 4.0 and 3.0 mu g ml(-1), re spectively, and corresponding detection limits are 49, 52 and 62 ng ml(-1). The synthetic samples are analyzed with relative standard deviation of fiv e measurements of 3.9-6.0%. DNA in an extraction product from human blood i s determined using the calibration graph for calf thymus DNA, and the resul t is very close to that by the ethidium bromide assay. Compared with some e stablished fluorometric methods, this procedure is sensitive, selective, re liable, reproducible and practical. The association constant of calf thymus DNA with the complex is estimated by two graphic methods. It is suggested that the binding reaction between nucleic acids with the complex proceeds i n an intercalation way. (C) 2000 Elsevier Science B.V. All rights reserved.