Method for quantification of purity of sub-visible particle samples

A method for quantification of purity of sub-visible particle samples, comprising:

• placing a sample in an electron microscope to obtain an electron microscopy image of the sample, the sample containing objects;
• enhancing the objects in the image having sizes being different from a size range of primary particles and sizes being within the size range of primary particles
• detecting the objects in the image as being primary particles or debris;
• excluding the detected primary particles from the objects so that objects contain debris but no primary particles;
• measuring a first total area (T1) of the detected debris;
• measuring a second total area (T2) of the detected primary particles;
• and
• calculating a ratio of the first total area (T1) to the second total area (T2) to determine a quantitative measurement of purity of the sample.