Thanks to all.

> If it is too clogged I just replace the 
> capillary.  When the pump will be out of use for a while (>3 days) I 
> flush it with water to prevent crystals forming in the capillary.

It seems that at least part of the problem was related to a clogged acid
needle and capillary which was not in use for 5 days.
Any hints to clean it? I tried heating up in hot water/ultrasonic bath
and air pressure but with no success. 
Does anyone now another supplier of needles that can be used for acid
dropping in the PAL? The acid needles from Thermo are quite expensiv -
espacially when they clog that fast....

greetings,
Robert

-- 
Dr. Robert van Geldern
Leibniz Institute for Applied Geosciences (GGA)
S3: Geochronology and Isotopehydrology
Stilleweg 2, 30655 Hannover, Germany
phone: +49-(0)511-643-2313 (office), -2539 (lab)
fax: +49-(0)511-643-3665
mailto:[log in to unmask]