Abstract

A sensitive and selective liquid chromatography–tandem mass spectrometry (LC–MS/MS) method was developed
for the quantitative determination of 3-ethynylaniline, a process related genotoxic impurity in synthesis
of erlotinib. The 3-ethynylaniline in erlotinib drug was analyzed on a Hypersil BDS C-8 (50 mm × 4.6 mm,
3 μm) column interfaced with a triple quadruple tandem MS operated in a multiple reaction monitoring mode.
Positive electrospray ionization was employed as the ionization source and the mobile phase used was 5.0 mM
ammonium acetate–acetonitrile (55:45, v/v). The developed method was validated as per ICH guidelines in terms
of specificity, limit of detection, limit of quantification, linearity, precision, accuracy, and robustness. This method
shows excellent sensitivity in the quantification of impurity at the level of 0.6 ppm with 1.9% relative standard
deviation. The calibration curve showed good linearity over the concentration range of 0.6-6.0 ppm with a
correlation coefficient of >0.9991. The accuracy of the method was between 96.26% and 100.64%.