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Author
Bugnion Dallerés, Linda A.
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Abstract
N-nitrosamines are molecules containing a nitrous functional group linked to an amine (R1N(-R2)-N=O) and since 2018 they have been detected as impurities in some pharmaceutical products. The first Nnitrosamine detected and reported to the Food and Drug Administration (FDA) was N-Nitrosodimethylamine (NDMA). NDMA presence is unacceptable in medicines because of its probable carcinogenic nature. The FDA published a provisional maximum daily intake limit of 0.096 μg NDMA/day.
The present work focuses on the development of a method to ensure that the concentration of nitrite in pharmaceutical samples does not exceed 0,010 mg/kg. To simulate pharmaceutical samples sodium chloride is used as a simulant of the formulated or active ingredient. Therefore, aqueous nitrite standards shall be prepared with a high chloride concentration (10 g/L). In a previous TFG, carried out by Oriol Rojas, several detection nitrite methods were studied and analysed. Th nitrite was previously derivatised or directly measured. The UV-VIS spectrophotometry technique with previous derivatization of the nitrite and the ion chromatography with DAD detector measuring nitrite directly were proved to be suitable for nitrite detection. The quantification limits were 0.03 mg/L and 0.05 mg/L, respectively.
On the other hand, the liquid chromatography technique using a reversed-phase column and a DAD detector to determine nitrites previously derivatised with Griess reagent was not suitable for several reasons. This TFG is based on the chromatographic method designed by Oriol Rojas and attempts to optimise it in order to achieve good sensitivity, selectivity and to improve the detection and quantification limits obtained.
In addition, this project also uses UHPLC liquid chromatography in tandem with a triple quadrupole mass spectrometer (UHPLC- MS/MS QQQ). The detector of this equipment has excellent sensitivity and selectivity and the UHPLC column allows a very good separation. The procedures performed with the UV-VIS spectrophotometer and the HPLC-DAD have been found to be selective, linear and accurate in the concentration range of 1-0.016 mg/L in the presence of high chloride concentrations. The method developed with the UHPLC-MS/MS QQQ is selective, linear and accurate in the concentration range of 0.013- 0.0031 mg/L. The theoretical LQ achieved was 0.00011 mg/L of analysed solution, equivalent to 0.007 mg/kg in simulant.
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