A novel liquid chromatography with quadrupole time-of-flight-tandem mass spectroscopy method for ultra-trace level identification and quantification of the genotoxic impurity 2,6-diamino-5-nitropyrimidin-4(3H)-one in valganciclovir hydrochloride.

In the present study, the main objective is to develop an analytical method for ultra-trace level measurement of 2,6-diamino-5-nitropyrimidin-4(3H)-one (DMNP) in valganciclovir hydrochloride (VAL) using liquid chromatography-quadrupole time-of-flight-tandem mass spectroscopy (LC-QTOF-MS/MS). In the early stages of guanine synthesis, DMNP is formed, and guanine is known to be the key starting material for the synthesis of VAL. Taking into consideration DMNP potential genotoxicity, this analytical method has been developed. This method is time saving and suitable for confirming the masses of parent and fragment ions by MS and MS/MS further fragmentation. An isocratic program and Acquity UPLC HSS cyano column (100 × 2.1 mm × 1.8 µm) were used to achieve optimal separation between VAL and the DMNP impurity. A 0.1% ammonia solution in Milli-Q water was used as mobile phase A, and methanol was used as mobile phase B in the ratio 90:10 v/v in isocratic mode. In accordance with the International Conference on Harmonization's requirements, the developed method was validated. The detection and quantification levels were found to be 0.028 and 0.083 ppm respectively. The DMNP impurity is linear from 0.083 to 1.245 ppm levels with correlation coefficient (R2 ) of 0.9960. The recoveries were found to be 97.0-107.9%.

Development and validation of LC-QTOF-MS/MS method for the identification and determination of low levels of a genotoxic impurity, 4,6-dichloro-5-nitro-2-(propylthio)pyrimidine in ticagrelor API.

The foremost objective of the present study was to develop and validate a new LC-QTOF-MS/MS method for the identification and quantitative determination of 4,6-dichloro-5-nitro-2-(propylthio)pyrimidine (DPP) genotoxic impurity through the derivatization process in ticagrelor active pharmaceutical ingredient (API). Owing to the low response of DPP at the specification level, DPP was converted to 4,6-dibenzylamino-5-nitro-2-(propylthio)pyrimidine (DPP derivative) by addition of benzyl amine, then analyzed using mass spectrometry with a time-of-flight analyzer, and good separation was accomplished under the experimental conditions described. The effective separation of DPP derivative was achieved using an Acquity UPLC BEH C18 reverse-phase column (100 × 4.6 mm × 1.7 µm) with an isocratic program with mobile phase A as 0.1% formic acid in milli Q water and mobile phase B as acetonitrile in the ratio of 20:80 v/v. The flow rate was maintained as 0.4 ml/min, the injection volume was 2 µl, the autosampler temperature was 5°C, the column oven temperature was ambient and the run time was 6.0 min. The diluent used was 0.2% benzyl amine in water and acetonitrile in the ratio of 30:70 v/v. The retention time of the DPP derivative was 2.87 min. The limit of detection and limit of quantification were 0.03 and 0.08 ppm, respectively. The DPP derivative was linear from 1.68 to 12.78 ppm with R2 of 0.9958. Thus, the developed method is valid for the identification and quantitative determination of DPP derivative in ticagrelor API.