This work demonstrates the accurate and precise quantification of the endogenous protein, Apolipoprotein A1 in plasma. Using the ProteinWorks eXpress Direct Digest Kit with 3-step protocol, the total sample preparation time was under 1.5 hrs. Through direct digestion of 15 μL of plasma, quantification limits of 5–1500 μg/mL were achieved, while maintaining linearity, precision and accuracy. This method easily distinguishes 5 μg/mL changes in Apo A1 in rat plasma and changes of 75 μg/mL over the endogenous level in human plasma. We’ve demonstrated that using a simple kit-based approach can eliminate the need for method development and allow bioanalytical labs with limited experience to quickly generate robust, accurate and precise data.