The TP, FD, and reduction rates were calculated for each concentration in this sample set, meaning the results of the no matrix, 100x dilution, and 10x dilution were combined for the 1000, 100, 50, 25, 10, 5, 2.5, and 1 µg/L spiked internal standards. The Pearson correlation coefficient was calculated between the sample concentration and the TPr, FDr, and reduction rate, which resulted in values of 0.23, 0.37, and 0.22, showing no correlation between the sample concentration and performance. Therefore, due to relatively low number of cases, 2149 for the 10 µg/L and 3702 for the 100 µg/L, it is more likely that the deviation is caused by the low number of cases being evaluated.