Chromatography Forum

Dear all,

i am working on LC-MS/MS, and facing problem of dropping of response,i have post the same topic, i am thinking that there is problem in skimmer if MS (Deposition of carbon on skimmer), can anyone have idea that how to wash the skimmer to overcome the problem,whether is it prefferable to consult the engineer or it can be done simply by ourself.

What are the precaution we have to take during washing.

Sadanand Mallurwar

It depends on the instrument, but it's usually not complicated. There are probably instructions in the instrument's manual (or pdf somewhere with instrument); it's definitely a good idea to ask the manufacturer as procedures can differ, and a poor choice of cleaning solvent can damage the skimmer depending on the alloy of which it's made. Usually it's merely a matter of wiping off the deposit with a cotton bud, or sonicating briefly in an appropriate solvent. If a skimmer is dirty, you may also need to clean other parts of the ion optics, for instance capillaries.

we just intalled a new la-ms,agilent 6410 triplequodiode .and certainly we dont do this by ourselves .maybe engineer will do this .and if you want do ,i think you must understand the construction of the instrument.then you do this under the document provided by instrument supplier.

we have a thermo ultra MS, and its very easy to remove the skimmer and tube lens, we ultrasonic monthly in methanol, and this seems to do the trick of getting them clean, and usually improves IS response also,.

Hi,
I use a Thermo LCQ andQuantum Access, it's easy to wash the skimmer, just turn off the system, pull the source out, unscrew the skimmer and wash with methanol, can sonicate.
You should wash the skimmer weekly if the instrument is used frequently. and should wash the heated capillary also. Both can improve much sensitivety.
But it depend on which instrument you have, i think you should read the instruction in user manuals or ask the engineers.

Thermo instruments seem to have easier skimmers to clean than Agilent. We only have an Agilent single quad, but if the triple is the same, it involves removing the desolvation unit, which is a large box containing heater and capillary; it's not scary to do, but it does involve a screwdriver (in contrast to Thermo) and a bit of fiddling around remembering which bits go where (not to mention retrieving lost screw from down the spray chamber drain, if you forget to block it with a bit of paper towel before starting).

Cleaning Agilent capillaries is also scarier, because they are glass with platinum plated ends, cost a fortune, and the approved method involves pulling a piece of cotton wool down the middle with a fine wire, a process where I can see me getting stuck half way. Nevertheless, it is still a procedure for which Agilent offer customer guidance.