Metformin bulk drug and method for determining content of N-nitrosodimethylamine in preparation of metformin bulk drug

The invention provides a method for determining the content of N-nitrosodimethylamine in a metformin bulk drug and a preparation thereof, and relates to the field of analytical testing. The method comprises the following steps: weighing an N-nitrosodimethylamine standard substance, adding a solvent for dissolving, diluting with a mixed solvent of acetonitrile and water to obtain a standard solution with required concentration, adding salt for salting out, centrifuging, and taking supernatant to obtain the treated standard solution; the method comprises the following steps: weighing a metformin bulk drug or a preparation thereof, adding a mixed solvent of acetonitrile and water for dissolving, adding salt for salting out, centrifuging, taking supernatant, and filtering to obtain a test solution; respectively detecting the treated standard solution and the test solution by a liquid chromatography-electrostatic field orbitrap mass spectrometry method, and calculating the content of N-nitrosodimethylamine in the