Greetings,
Finnigan changed the design of the acid needle in the Gasbench.

The new needle is thinner and very flexible.
However, the drops are smaller than using the old, thick needle.
Due to the smaller drops it seems that more drops are necessary for the
complete reaction of the carboante sample. Dropping of 5 to 8 drops does
not work, since the acid volume transfererd into the vial is to small
and the sample is not dissolved at all or only in parts.

So, we incereased the number of drops up to 15. Consequently, the
dropping times increases dramatically. This causes another problem:
Due to the long dropping time the CO2 in the vial to be measured (with
sample needle in) is already diluted by the helium flow into the vial.
So the CO2 does not last for 10 sample peaks.

I incereased the volume of the acid pump to maxium (450mikroliter per
stroke). It still takes 20 strokes per drop!! So for 15 drops you will
need 300 strokes...

Any suggestions?


Robert


-- 
Dr. Robert van Geldern
Leibniz Institute for Applied Geosciences (GGA)
Section 3: Geochronology and Isotope Hydrology
Stilleweg 2, 30655 Hannover, Germany
phone: ++49-511-643-2313
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