Method for determining content of olaflur in toothpaste by liquid chromatography-tandem mass spectrometry

A method for determining content of olaflur in toothpaste by liquid chromatography-tandem mass spectrometry, comprising the following steps:

• obtaining to-be-tested toothpaste;
• dissolving the to-be-tested toothpaste in water and then adding methanol for dilution to obtain a to-be-tested solution;
• and placing the to-be-tested solution in a liquid chromatograph for determination under following chromatographic conditions:
• a C4 column;
• a mobile phase as a combination of phase A being methanol with 0.1% formic acid and phase B being acetonitrile, or a combination of phase A being methanol with 0.1% formic acid and phase B being water;
• and isocratic or gradient elution;
• wherein
• when an external standard method is used to quantitatively determine olaflur, an olaflur standard is dissolved in a methanol solution to obtain olaflur standard solutions with different concentrations, and the olaflur standard solutions are determined under same chromatographic and mass-spectrometric conditions;
• based on determination results, a standard concentration-response intensity curve is drawn to record a relationship between olaflur concentration and response intensity;
• and the content of olaflur is obtained based on the standard concentration-response intensity curve according to the response intensity of the to-be-tested solution in the liquid chromatograph;
• and
• when an internal standard method is used to quantitatively determine olaflur, an olaflur-D8 internal standard is dissolved in water or a methanol solution to prepare an olaflur internal standard solution, an olaflur standard is dissolved in a methanol solution to obtain an olaflur standard solution, and the olaflur internal standard solution is mixed with the olaflur standard solution to obtain mixed olaflur internal standard solutions with different concentrations;
• the mixed olaflur internal standard solutions are determined under the same chromatographic and mass-spectrometric conditions, and a concentration ratio-response intensity ratio curve is drawn based on determination results and a relative correction factor;
• the to-be-tested toothpaste is dissolved in water, then methanol is added for dilution, the olaflur-D8 internal standard is added to obtain a to-be-tested solution, and the content of olaflur is obtained based on a concentration of the to-be-tested solution in the liquid chromatograph and the concentration ratio-response intensity ratio curve.