Limits Identify any peaks corresponding to impurities 1 and 5 in the chromatogram obtained with solution (1), using the chromatogram obtained with solution (3), and multiply the area of these peaks by a correction factor of 0.6 and 0.8, respectively. In the chromatogram obtained with solution (1): the area of any secondary peak is not greater than the area of the peak due to sitagliptin in the chromatogram obtained with solution (2) (0.2%); the sum of the areas of all secondary peaks is not greater than the area of the peak due to sitagliptin in the chromatogram obtained with solution (2) (0.2%). Disregard any peak due to metformin and any peak with an area less than half the area of the peak due to sitagliptin in the chromatogram obtained with solution (2) (0.1%)