Microreagent A

0.8 g Na₂CO₃•H₂O

1.6 g NaOH

1.6 g sodium tartrate•2H₂O

Adjust the volume to 100 mL with H₂O. Stir the solution and adjust the pH to 11.5 with 10 M NaOH. Microreagent A is stable for 1-3 wk when stored in a plastic container at room temperature, and indefinitely at 4ºC.