Uncovering Deficiencies in Mass Balance Using HPLC with Chemiluminescence Nitrogen-Specific Detection

with amperometric detection. It has been shown elsewhere that the selectivity of this method is sufficient to separate the potential organic impurities; that is, synthesis byproducts and a specified degradation product from the drug substance (3). The objective of this article is to demonstrate that this method’s suitability for stability testing can be evaluated easily by performing HPLC with chemiluminescence nitrogen-specific detection as a reference method (4). Nitrogen-specific detection first was used in gas chromatography for the determination of nitrosamines (5). Coupling a nitrogen-specific detector with an HPLC system required some modifications, but it proved to be a useful instrument for quantifying peptides without the need for prior derivatization (6). Researchers have described applications for biochemical analysis (7,8) and combinatorial chemistry (9). Until now, the use of chemiluminescence nitrogen-specific detection for method validation and impurity profiling (10), including complete mass balancing for pharmaceutical applications, has not yet been published in the literature, to my knowledge. The principle of operation for the nitrogen-specific detector used begins with the complete high-temperature oxidation of The author describes using high performance liquid chromatography (HPLC) with chemiluminescence nitrogen-specific detection and amperometric detection to determine organic impurities in a tedisamil dihydrochloride drug substance. The results obtained confirm the validity of the method and its ability to clarify deficiencies in mass balance during forced degradation. The HPLC method with amperometric detection was acceptable as a stability-indicating method for routine stability testing of the drug substance and the dosage form. The chemiluminescence nitrogenspecific detection method, however, provided reliable, more-accurate results that revealed markedly less deficiency in mass balance. Uncovering Deficiencies in Mass Balance Using HPLC with Chemiluminescence Nitrogen-Specific Detection