Reagent preservation
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Although most chemical compounds can be stored indefinitely (ex: sodium chloride, barium sulfate, etc.) in most if not all storage conditions, there are quite a lot of reagents that tend to undergo chemical changes, regardless of the storage. Even in the best storage conditions, they will degrade over long periods of time. To maintain the long shelf life of them, preservatives as well as other additives are added.
Contents
General
Many chemicals, such as ether tend to undergo autoxidation, when in contact with air. Halogenated carbons will too suffer similar effects.
Other compounds, such as sugar or citric acid will serve as nourishment for mold or other biological organisms.
Note that preservatives have poor efficiency if you do not store your reagents properly.
Reagents and preservatives used
| Compound | Preservative | Notes |
|---|---|---|
| 1,4-Dioxane | Butylated hydroxytoluene (BHT), Butylated hydroxyanisole (BHA), fresh copper | |
| Acrolein | Hydroquinone | Does not always work, possibly due to impurities[1] |
| Barium ferrate | Potassium hydroxide, sodium hydroxide | |
| Chloroform | Ethanol, methanol | |
| Citric acid | Anti-fungal agents | Aqueous solutions and wet citric acid are prone to mold; solid or anhydrous citric acid less so |
| Dichloromethane | Ethanol, methanol | |
| Diethyl ether | Butylated hydroxytoluene (BHT), Butylated hydroxyanisole (BHA), fresh copper | |
| Diisopropyl ether | Butylated hydroxytoluene (BHT), Butylated hydroxyanisole (BHA), fresh copper | The amount of preservative added must be greater compared to other ethers |
| Hydrogen peroxide | Phosphoric acid | |
| Lead(II) azide | Dextrin | Generally used in Pb(N3)2 aqueous solutions and during production |
| Lead(IV) acetate | Anhydrous acetic acid | |
| Methyl iodide | Copper or silver wire/powder | |
| Pentaerythritol tetranitrate | Urea | |
| Potassium ferrate | Potassium hydroxide | |
| Schweizer's reagent | Excess ammonia | |
| Smokeless powder | Diphenylamine | |
| Sodium ferrate | Sodium hydroxide | |
| Tetraamine copper(II) complex | Excess ammonia | |
| Tetraaminecopper(II) persulphate | Excess ammonia | |
| Tetrahydrofuran | Butylated hydroxytoluene (BHT), Butylated hydroxyanisole (BHA), fresh copper |
