European Journal of Biomedical and Pharmaceutical Sciences

A HIGHLY SENSITIVE LC-MS/MS METHOD FOR THE DETERMINATION AND QUANTIFICATION OF A N-NITROSAMINE IMPURITY IN THE TIMOLOL MALEATE ACTIVE PHARMACEUTICAL INGREDIENT

Vinayak T. Vele*, Kishor More, Vishal Telvekar, Shivaji Kadam, Mohan A. Chandavarkar

ABSTRACT

A liquid chromatography-tandem mass spectrometry (L C-MS/MS) method was developed for the quantification of n-Nitrosamine Timolol maleate impurity (NTML) in the Timolol maleate active pharmaceutical ingredient. Chromatographic separation was achieved using a Waters Acquity HSS T3 C18 column, with 0.01 mol L-l ammonium formate in water as mobile phase A and 0.1% formic acid in methanol as mobile phase B in gradient elution mode at a 0.25 ml/ min flow rate. Quantification of impurities was carried out using triple quadrupole mass detection with electrospray ionization in the multiple reaction monitoring mode. The method was fully validated with good linearity over the concentration range of 0.0061-0.0303 ppm of the Timolol Maleate test concentration for NTML. The correlation coefficient obtained in each case was >0.9994. The recoveries were found to be satisfactory over the range between 80 .0 and 120.0 % for NTML. The developed method was able to quantitate NTML at a concentration level of 200 ng mL-l (0.02 ppm with respect to 100 mg mL-1 Timolol Maleate).

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