How reliable are broad standards?
In most cases, broad standards that are commercially available have been well characterized by techniques that provide a reasonable Mw, Mn, Mz, etc. There is a certain amount of trust in purchasing these standards that the values reported are accurate and obtained with excellent precision. After all, your calibration curve is based on these values. One can also send out a representative sample that is typical of samples run in the laboratory for analysis by these ancillary techniques. Many contract labs and universities can perform these analyses and provide you with Mn, Mw, Mz, etc. on your sample that you wish to use as a broad standard.
