Справочник Пользователя для SSI America BINARY SOLVENT DELIVERY MODULE 90-2581 REV B

Скачать
Страница из 48
 
 3-3 
 
2.4 Electrical 
Connection 
 
       The system utilizes Universal Switching Power Supply, and will 
accept voltages from 90 – 260 VAC, 50-60 Hz. 
WARNING:  Do not bypass the safety ground connection as 
a serious shock hazard could result. 
2.5 Solvent 
Preparation 
Proper solvent preparation will prevent a great number of pumping 
problems. The most common problem is bubble formation, which may 
affect the flow rate consistency. Aside from leaky fittings, the problem 
of bubble formation arises from two sources: solvent out-gassing and 
cavitation. Filtration of HPLC solvents is also required. 
2.5.1 Solvent 
Out-gassing and Sparging 
Solvent out-gassing occurs because the mobile phase contains 
dissolved atmospheric gases, primarily N2 and O2. These dissolved 
gases may lead to bubble formation and should be removed by 
degassing the mobile phase before or during use. The best practical 
technique for degassing is to sparge the solvent with standard 
laboratory grade (99.9+%) helium.  Helium is only sparingly soluble 
in HPLC solvents, so other gases dissolved in the solvent diffuse into 
the helium bubbles and are swept from the system. Solvent filtration is 
not an effective alternative to helium degassing. 
 
It is recommended that you sparge the solvent vigorously for 10 to 
15 minutes before using it.  Then maintain a trickle sparge during use 
to keep atmospheric gases from dissolving back into the mobile phase. 
The sparged solvent must be continually blanketed with helium at 2 to 
3 psi.  Non- blanketed, sparged solvents will allow atmospheric gases 
to dissolve back into the mobile phase within four hours. 
 
Solvent mixtures using water and organic solvents (like methanol or 
acetonitrile) hold less dissolved gas than pure solvents.  Sparging to 
reduce the amount of dissolved gas is therefore particularly important 
when utilizing solvent mixture. 
 
 Even with sparging some out-gassing may be occur.   A back 
pressure regulator installed after the detector flow cell will help 
prevent bubbles from forming and thus limit baseline noise. 
 
WARNING: Always release pressure from the pump slowly.  A rapid 
pressure release could cause the pulse damper diaphragm to rupture.