A mathematical approach described as most useful for calculating gamma globulin content when concentrations are unchanged is which of the following?

• A. Direct ratio of total area to gamma globulin area
• B. Graphical interpolation
• C. Linear regression
• D. Integration

Answer: (A)

Measuring with densitometry relies on the fact that peak areas are proportional to the amounts of protein loaded. When the concentration stays the same, both the total protein area and the gamma globulin area scale by the same loading factor, so their ratio is independent of how much sample was applied. Using the direct ratio of total area to gamma globulin area gives a simple, load-independent measure of how much gamma globulin is present relative to all protein, making it the most straightforward way to calculate gamma globulin content under fixed concentrations. Other methods require additional standards or calibration (graphical interpolation or linear regression) or don’t directly exploit the proportionality in a single measurement, which is why they’re less efficient in this scenario.