Quinoxalinone derivatization of biological carboxylic acids for detection by peroxyoxalate chemiluminescence with...

A quinoxalinone fluorescent tag is evaluated as a carboxylic acid derivatizing reagent for detection by peroxyoxalate chemiluminescence. The synthetic procedure for the quinoxalinone was modified to give a yield that is significantly increased over that reported previously. The new conditions use less hazardous reagents, and produce a final product greater than 97% pure, without the need for intermediate clean-up steps. The derivatization reaction is also modified to give increased yields of greater than 85% compared to 74% obtained previously. The post-column chemiluminescence reaction conditions are optimized to give detection limits of 500 attomole/injection-10 times lower than the fluorescence previously obtained. The reagent is used for the first time on a plasma sample extract. Typical method precision is 4%.