Does Hach sell a sulfide standard or can one be prepared?
For Method 8131 a premade standard is not available for purchase. The reason Hach does not sell one is because sulfide standards are unstable and the shelf life would be short. Standard Methods 4500-S2- lists sulfide standard preparation instructions:
-Take 3.725 Na 2 S*9H 2 O diluted to a final volume of 500 mL. This will give a stock solution of which 1mL = 1.00 mg/L S 2-.