A new fluorescent probe for sensitive detection of carbonyl compounds: sensitivity improvement and application to environmental water samples

The use of 2-aminooxy-N-[3-(5-dimethylamino-naphtalene-1-sulfonylamino)-pro pyl]-acetamide (dansylacetamidooxyamine, DNSAOA, 2) as a new molecular prob e for trace measurement of carbonyl compounds (i.e. aldehydes and ketones) in water samples is reported. 2 can be considered as an evolution of the pa rent N-(5-dimethylamino-1-naphtalenesulphonamido)-3-oxopentane-1,5-dioxyami ne (dansyloxyamine, DNSOA, 1) molecule that was initially proposed in a rec ent paper. An updated procedure for the synthesis of 2 leading to higher pu rity of such oxyamino probes and a subsequent better sensitivity of the met hod was described. The reactivity behaviour of 2 with solutions containing small amounts of formaldehyde, acetaldehyde, propionaldehyde and acetone is also described: even for concentrations less than 1 mu M, C1-C3 aldehydes can be fully derivatized within 10h and only one calibration curve is neede d. Longer reaction times are nevertheless required for accurate measurement s of the less reactive acetone. Very low limits of detection (LODs), mainly depending on the initial purity of the probe, have been obtained: 10 nM of formaldehyde and 5 nM of the other carbonyls can be detected. The limit of quantification (LOQ) of the method is close to 25 fmol. 2 was used in meas uring the carbonyl content of snow, ice and cloud-water samples. The first data concerning acetaldehyde in alpine and polar snow, and a first estimati on of acetone in cloud-water droplets are reported here. (C) 2000 Elsevier Science B.V. All rights reserved.