[Michaelmoo]

So I know there are two major ways of determining optical purity of a chemically pure sample:

1) Performing a CSP-HPLC, and using the relative peak areas of each enantiomer as a measure (i.e. using Optical purity = (A-B)/(A+B)

2) Measuring the specific rotation of a sample and comparing it to the specific rotation of an optically pure sample. i.e. Optical purity = Specific rotation of sample/specific rotation of pure sample

My question now is, which method is most appropriate when you have a very SMALL amount of the molecule to be measured and why?

Thanks in advance.