A proposed limit test for p-chloroaniline impurity in paracetamol pharmaceutical formulations

P-chloroaniline is a polar organochlorine compound and an important member of aromatic amines, widely used in various industries, including pesticides, dyes, and pharmaceuticals. Exposure to high levels of P-chloroaniline can cause severe damage to the liver and kidneys and negatively affect the central nervous system. Recently, concerns have been raised about P-chloroaniline as a contaminant in paracetamol pharmaceutical formulations. Interestingly, this impurity is neither controlled in the API nor in the finished paracetamol products. Consequently, a rapid, sensitive, and selective liquid chromatography mass spectrometry (LC/MS) method was developed and applied as a limit test for the determination of P-chloroaniline in 11 paracetamol pharmaceutical formulations. The LC separation was carried out with a C18 column at 35 ℃ with a mobile phase of 0.1% Methanol: 0.1% formic acid (50:50 v/v). Additionally, P-chloroaniline ions were monitored at 127.9/93 and 127.9/111.0 as qualifier and quantifier ions, respectively, using an ESI ion source. The method was validated as a limit test according to ICH Q2 (R1) guidelines and showed high sensitivity and specificity for the determination of P-chloroaniline in paracetamol formulations. Implementing the method for commercial sample analysis revealed its suitability as a new strategy to ensure product compliance with the quality standards.