The T3 from Sigma T5516-1mg bottle. MW is 672.96 g/mol.

The Spec sheet for the SUM102 PT cells says use 20ug/ml stock concentration to get a final concentration of 6.7ng/ml (10nM) and add 168ul to 500ml medium. T3 has to be diluted in 0.1M NaOH. How to get the required 20ug/ml stock from 1mg total in bottle? The calculations I did required using a vanishingly small mass of T3. I would like to know a better approach to handling complex media supplements. Thank you