Using second-derivative filters to assist in width estimations of size exclusion chromatography signal peaks with static light-scattering detections to obtain more accurate molecular weight.

Static light-scattering (LS) detection can determine the molecular weight (MW) of polymers eluted with size-exclusion chromatography (SEC) without using any standards when the differential refraction index (RI) of solutes are obtained. On the other hand, the noisy chromatographic signal peak acquired using a static LS detector often causes difficulty in peak-width recognition. This disadvantage limits the determination accuracy and precision of the MW values. This study developed one second-order derivative filtering procedure by convolving the original LS chromatogram against the second-derivative curve of one artificial Gaussian-shape chromatographic peak to suppress the noises and to correct the baseline of the chromatogram. More accurate estimations of the chromatographic peak widths of pullulan samples were achieved to improve the MW determination accuracy. For noisy original chromatography peaks of pullulan 5 k (SNR of approximately 10), the non-ideal determination accuracy of the MW values (9.3%) is improved to -1.3% with the assistance of the filtering procedures.