Liquid chromatography–mass spectrometry with chemiluminescent nitrogen detection for on-line quantitative analysis of compound collections: advantages and limitations

Recently, alternative detection methods such as chemiluminescent nitrogen detection (CLND) have been coupled successfully with HPLC for quantification. This detector produces a signal proportional to the number of moles nitrogen present in the compound. Sample concentration of compounds with a known formula can be determined by use of an external calibration standard such as caffeine. Hence, the CLND can be used without the need for primary standards of the compound with unknown concentration, which enables the use of this detector for high-throughput analysis. In this work, the reliability and pitfalls of this coupled LC–MS/CLND are demonstrated. Nitrogen detection is specific as it only gives a response for nitrogen containing compounds and universal since it only gives a linear response. Nevertheless the lower response for NN and NN containing compounds has been evaluated in this study.