In Article <3v5l1q$6v2 at fu-berlin.de>
strecker at chemie.fu-berlin.de (Andreas Strecker) writes:
>In article <11EF24B23F5 at botany.uq.edu.au>,
>J.Marcus at botany.uq.edu.au ("Marcus, Dr J.") wrote:
>>Dear Netters,
>> I have been struggling with our Waters HPLC
>>for over a month now and would appreciate ANY clues
>>that might help sort out the problem. If there is any
>>interest, I will post a summary of responses.
>> The problem manifests itself as an extremely wavy
>>baseline which coincides with the pump cycle of pump B
>>(6000A Series pump with dual piston design). After
>>changing the pump seals and check valves, the problem
>>remains. Every indication now seems to point to a bubble in
>>one of the pump heads; but, try as I may, I have not been
>>able to get rid of it. I have tried pumping methanol; I
>>have used the solvent draw-off valve to pressurize the
>>intake line while the pump is going at 10ml/min; I have
>>tried tapping the pump head.
>>>>John Marcus
>>>Dear John!
>>I have two hints for you, both might work:
>>1. Maybe your UV-lamp is worn out. There should be a diagnostics possibility
>at your detector (we have a series 486 detector, it's "Diagnostics" "019"
>Enter). This should give you a value for the remainig lamp power. If it is
>low, you have to replace it (very expensive).
>2. We had this problem after exchanging the tubing between pumps and column
>for a narrower tubing. Maybe your tubing is to narrow. Did you change it?
>>I suppose it is the lamp, since I find getting rid of air bubbles in the
>Waters system fairly easy.
>>Good luck!
>>Andreas
>>(Call back for further questions!)
Dear John,
I have another possibility:
We just bought a new HPLC system and to my horror the baseline had huge
oscillations. The detector was the same as I used before. Finally we found out
what the main difference between the new and old system was, in the new system
there was no pulse damper. The noise we were looking at was the pump, if you
have a gradient you get very nice sinus waves. The solution is to buy a
pulse damper, the disadvantage is that the system takes longer to equilibrate.
Greetings
Jurgen
