Here, w 1 denotes the full width of half maximum, and parameters w 2 and w 3 represent the variance of the left-and right-sides of the peak, respectively. Consequently, a symmetrical distribution is recovered when w 2 = w 3 . The retention times of the two distributions were fixed together with the width of the Gaussian peak and the offset to reduce the number of parameters during fitting. The monomer concentration was determined from the area of the Gaussian peak.