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

Abstract

The use of 2-aminooxy- N-[3-(5-dimethylamino-naphtalene-1-sulfonylamino)-propyl]-acetamide (dansylacetamidooxyamine, DNSAOA, 2) as a new molecular probe 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 parent N-(5-dimethylamino-1-naphtalenesulphonamido)-3-oxopentane-1,5-dioxyamine (dansyloxyamine, DNSOA, 1) molecule that was initially proposed in a recent paper. An updated procedure for the synthesis of 2 leading to higher purity of such oxyamino probes and a subsequent better sensitivity of the method 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 μM, C1–C3 aldehydes can be fully derivatized within 10 h and only one calibration curve is needed. Longer reaction times are nevertheless required for accurate measurements 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 measuring the carbonyl content of snow, ice and cloud-water samples. The first data concerning acetaldehyde in alpine and polar snow, and a first estimation of acetone in cloud-water droplets are reported here.