Synthesis of 2-methyl-6-methoxy-4-quinolinecarboxylic acid N-hydroxysuccinimide ester (MMQC-OSu) for streamlined and effective HPLC-based fluorescence detection of aliphatic amines in environmental samples.

Aliphatic amines are widely distributed in the environment and food sources, posing potential health risks through skin and mucosal irritation. Consequently, their quantitative detection is crucial for assessing environmental health. Despite high reactivity and fluorescence properties of succinimidyl ester-based derivatization reagents, their application in the aliphatic amines detection is hampered by challenges such as limited detection sensitivity and fluorescence interference. We established an innovative synthetic approach to produce a series of succinimidyl esters with the desirable substituents. This advancement enabled the creation of efficient and highly sensitive reagents for the detection of aliphatic amines. Among them, 2-methyl-6-methoxy-4-quinolinecarboxylic acid N-hydroxysuccinimide ester (MMQC-OSu) exhibited the best detection performance. MMQC-OSu reacted with aliphatic amines at 40 °C in pH 8.0 buffer for 20 min, which was subsequently separated in a C18 chromatographic column with the fluorescence detection wavelength of 336/432 nm. This detection approach featured a rapid and mild reaction process, minimal interference from corresponding hydrolysis products, and impressive sensitivity (0.05 nM). These characteristics indicate that MMQC-OSu significantly surpassing commercial aliphatic amines detection reagents. Finally, the detection strategy of MMQC-OSu was successfully applied in environmental sample analysis, with recovery rate of 93 %-108 % and RSDs between 1.4 % and 6.5 %.