Simple, selective, and identifiable analysis of aromatic monoamines with a surrogate on sulfuric acid impregnated filters by derivatization with an acid chloride reagent and HPLC with fluorescence detection

A simple and selective derivatization and detection method for o-toluidine, o-anisidine, and 2,4-dimethylaniline was developed using a sulfuric acid impregnated filter, 4-(N-chloroformylmethyl-N-methylamino)-7-nitro-2,1,3-benzoxadiazole, and a surrogate (o-ethylaniline), which allowed simple, rapid, selective, and identifiable analysis by high-performance liquid chromatography with fluorescence detection. These amines were successfully derivatized in a pH 5 buffer solution containing acetonitrile at 35 degrees C for 10 min (linear in the range 0-400 ng/mL, n = 5, aromatic amines: r > 0.9980, aromatic amines with surrogate correction: r > 0.9997, aromatic amines in the presence of phenol and aliphatic amines with surrogate correction: r > 0.9996). The retention times of these derivatized aromatic amines were < 17 min using isocratic elution. No derivatives corresponding to phenol or the aliphatic amines (i. e., cyclohexylamine and hexylamine) were detected in the reaction solution. This method can therefore be considered applicable for the analysis of samples from occupational environments, as samples were successfully extracted, derivatized, and measured by high-performance liquid chromatography following spiking of a sulfuric acid impregnated filter with aromatic amines, phenols, and aliphatic amines. Indeed, only the aromatic amines were quantitatively detected without pretreatment, with no other spiked compounds being detected.