Special emphasis is placed on new aqueous-phase derivatization agents.
In addition, this method did not produce the expected sensitivities or low limits of detection. Therefore, derivatization with ethylchloroformate was explored, making possible the detection of most alpha-ketoacids, but with very low sensitivity and less satisfactory limits of detection than in the previous method. The derivatization yield of ketoacids with ethylchloroformate was found to be highly dependent on the composition of the reaction medium. Under the proper conditions, 2-NPH only reacts with acids, avoiding interferences from ketones or aldehydes, compounds that usually are present in real samples. Additionally, the derivative forms a very stable negative ion, allowing its detection by negative ion electrospray mass spectrometry.