Method and composition for quantifying protein using tagged standards

A method of quantifying a protein, the method comprising:

• electrophoresis reference composition and the protein in respective lanes of a gel, the reference composition including quantitation standards of different size each including a tag present at a different concentration;
• transferring the quantitation standards and the protein from the gel to a solid support to create a blot;
• detecting luminescence from the blot to obtain respective luminescence values separately representing an abundance of the tag of each quantitation standard and an abundance of the protein, wherein detecting luminescence is performed using plural luminescence images representing luminescence detected from the blot for different amounts of time;
• and
• determining a quantity of the protein using the respective luminescence values, wherein determining a quantity uses a first luminescence value obtained from a first luminescence image representing a shorter detection time and a second luminescence value obtained from a second luminescence image representing a longer detection time, and wherein the first luminescence value corresponds to a first quantitation standard having a higher concentration of the tag and the second luminescence value corresponds to a second quantitation standard having a lower concentration of the tag.