Dear Per,

we use a Finnigan MAT delta S and three years ago we had serious problem
with sensitivity and stability. The problem was in the ion source
controll unit. Our building was renovated and a fíne dust settled on the
electronic parts of the ion source controll unit causing stability and
sensitivity problems. I cleaned this "unit" and it helped for less than
a year, then the same problem came back and at last the "unit" became
dead. We called the service engineer, he found 1 transistor and two
diodes to be dead. After replacing these electronic parts, the original
sensitivity came back and the mass spec worked well again.

So may be your sensitivity problem originates from the ion source
controll unit.

Best regards
Istvan Forizs

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Dr. FÓRIZS István                            Istvan FORIZS Ph.D.
Magyar Tudományos Akadémia        Laboratory for Geochemical Research
Geokémiai Kutatólaboratóriuma        Hungarian Academy of Sciences
Cím/Address: H-1112 Budapest, Budaörsi út 45.   Hungary
Tel./Phone: (36-1)-309-2600/ mellék/extension 1151
Fax: (36-1)-319-3137
Http://www.geokemia.hu/people/forizs_hu.html
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