Solvents storage

Crude sulfur vesicants are relatively stable and stability increases with purity Distilled materials show very little decomposition on storage. Solvents such as carbon tetrachloride and chlorobenzene have been added to enhance stability of crude material. Agents can be stored in glass or steel containers, although pressure may develop in steel containers. Sulfur vesicants rapidly corrode brass and cast iron, and permeate into ordinary rubber. 

Adsorbent type Flushing solvent Storage solvent... 

If the column is not used for a short period of time, for example, overnight or over the weekend, the column is preferentially stored in the mobile phase, in which it is used. This minimizes equilibration times on startup. However, for longer storage, the column should be stored in the solvent that the manufacturer recommends for a particular column. For bonded phases used in reversed-phase chromatography, the most common solvent is an organic solvent such as methanol or acetonitrile. Nonaqueous solvents minimize the hydrolysis of silica-based bonded phases. When the column is converted to such a solvent, care should be taken to remove any salt prior to the conversion. It is highly recommended to put a label on the column that describes the storage solvent. 

If a cyanopropyl column needs to be exposed to solvents of intermediate polarity, for example during cleaning procures, the flow should not be interrupted. The pressure actually holds the particles in place, and a collapse of the bed is less likely to occur. The preferred storage solvent for normal-phase anopropyl columns is a hydrocarbon like hexane. 

Stabilizer, storage coating materials Adekacol EC-3000 Adekacol EC-4500 stabilizer, storage solvent-based paints BYK -EP N 20094 stabilizer, stoving alkyds EipoUn A... 

In addition to keep lipid extracts under an atmosphere of nitrogen, it is also advisable to add synthetic antioxidants, such as butylatedhydroxytoluene (BHT) to storage solvents at a level of 50-100 mg/L. This compound generally does not interfere with ESI-MS analysis of lipids and can be readily removed as it is relatively volatile. However, it should be noted that excessive amounts of antioxidants can sometimes act as pro-oxidants ... 

Equilibration A column is typically equilibrated with 20 column volumes of mobile phase at 1.0 mL/min. The void volume of a 250 x 4.6 mm column is considered 3 mL meaning that an hour is a good equilibration time. Never store CSPs in contact with buffer present no matter the pH. Always wash the CSP with water and then with an anhydrous organic solvent like methanol, ethanol, or acetonitrile. In sequencing mobile phases, especially on the multimodal phases, proceed from the storage solvent to the polar organic mode and then to the RP mode. Follow the RP mode with water, then anhydrous ethanol (stabilized with IPA), and then proceed to heptane/ethanol NP mobile phase. Acetonitrile can then be used to remove the heptanes and the column can be stored or displaced with methanol to start the process over. 

---