Aniline-based catalysts as promising tools to improve analysis of carbonyl compounds through derivatization techniques: preliminary results using dansylacetamidooxyamine derivatization and LC-fluorescence.

Derivatization techniques based on α-effect amines and H+ catalysis are commonly used for the measurement of carbonyl compounds (CCs), whether in environmental, food, or biological samples. Here, we investigated the potential of aniline-based catalysts to improve derivatization rates of selected carbonyls by using dansylacetamidooxyamine (DNSAOA) as a reagent. Kinetic experiments were performed in aqueous solutions by varying catalyst and CC concentrations and delivered insights into the reaction mechanism. Using anilinium acetate (AnAc), rate constants varied linearly with the catalyst concentration with rate enhancements toward H+-catalyzed reactions as high as ca. 90 and 200 for acetone and benzaldehyde, respectively. Owing to contamination problems when using AnAc, anilinium chloride (AnCl) was chosen for the optimized analysis of real samples at low concentration. Rate enhancements for derivatization reaction of 4.4 (methylglyoxal), 6.0 (glyoxal), 12 (acetone), 20 (formaldehyde), and 47 (hydroxyacetaldehyde) were obtained using 0.1 M AnCl. The optimized method was successfully applied to the determination of the above compounds in natural snow and meltwater samples. Limits of detection (LODs) and limits of quantification (LOQs) were in the 2-14 and 7-41 nM range, respectively, i.e., low enough to allow for the analysis of most natural samples. Satisfactory relative recoveries (92.8 ± 3.8-118.3 ± 4.4%) and intra-day precision (2.7-11.3%) were achieved. Finally, we think that this approach could be applied not only to every α-effect nitrogen reagent-with the most evident profit of lowering derivatization times and particularly those required for low-reactive ketones-but also to the derivatization of CCs onto coated solid sorbents.