Development of NIST SRM 2881, An Absolute Molecular Mass Distribution Polymer Standard*

摘要

Currently, all absolute molecular mass standards provide a single moment (e.g. Mn) of the molecular mass distribution (MMD). (By absolute it is meant that the standard is based on direct measurement of a physical property and not on calibration against another polymer.) We present a strategy to create an absolute molecular mass distribution polymer Standard Reference Material using MALDI-TOF MS. To create such a standard our methods must be free of operator bias (intentional or unintentional). Furthermore, the Type A ("random") and Type B ("systematic") uncertainties must be determined for each part of the experiment. The required unbiased, repeatable steps are 1) sample preparation, 2) instrument tuning, 3) data collection, and 4) data analysis. These steps ultimately lead to a signal intensity calibration function that relates the true MMD of the analyte to the MMD measured by mass spectrometry.