Prepare a 0.1 M Sodium Thiosulfate (STS) stock solution by dissolving 1.58 g of Sodium Thiosulfate (Product No. S7026) into 100 mL of water. Prepare a 0.1 M Silver Nitrate stock solution by dissolving 1.7 g of Silver Nitrate (Product No. S7276) into 100 mL of water. Store the stock solutions in the dark until needed to prepare the STS.
In general, the STS is prepared with a molar ratio between silver and thiosulfate of 1:4, respectively. Nearly all of the silver present in the solution is in the form of [Ag(S2O3)2]3-, the active complex for ethylene effect inhibition.
Prepare a 0.02 M STS by slowly pouring 20 mL of 0.1 M silver nitrate stock solution into 80 mL of 0.1 M sodium thiosulfate stock solution. The STS can be stored in the refrigerator for up to a month. However, preparation of the STS just prior to use is recommended.