. Author manuscript; available in PMC: 2016 Mar 17.

Published in final edited form as: Crit Rev Anal Chem. 2016;46(2):93–105. doi: 10.1080/10408347.2014.980775

Table 2. Slope and intercept values observed in linear regression equations resulting from different days of routine analysis of TCPY and 3-PBA.

Analysis Day	Linear Regression Equation
Analysis Day	3-PBA	TCPY
Day 1	y = 2.727 * x − 0.010	y = 2.522 * x − 0.014
Day 2	y = 2.668 * x − 0.009	y = 2.498 * x − 0.000
Day 3	y = 2.552 * x − 0.009	y = 2.646 * x + 0.007
Day 4	y = 3.014 * x − 0.013	y = 3.657 * x + 0.012
Day 5	y = 2.959 * x − 0.013	y = 4.105 * x − 0.006
Day 6	y = 2.792 * x − 0.012	y = 4.526 * x − 0.009

Note: Calibration curves were plotted using relative response values (y) and relative concentrations (x). Relative response is calculated by dividing the response of analyte by the response of its assigned internal standard. The relative concentration is calculated by dividing the expected concentration by the internal standard concentration contained in each level of standard.