To calibrate response, both peak areas and amounts on column are needed. Without a standard analyte, the only amount known was the amount of total castor oil and the peak areas of the many analytes. RRR, being the most abundant analyte in the sample, was used for the initial calibration. Thus, the first calibration curve used the total amount of castor oil analyzed, plotted against the RRR peak area. Calibration data were fit using an inverse second-order polynomial. The correlation coefficient, r2, was 0.9999, and precision was found to be high, with RSD values of 0.05–0.79% for RRR across the entire
range of amounts analyzed. .