The β-radioactivity of HPLC eluent were measured by homogeneous and heterogeneous scientillation.

Two kinds of flow cells were designed and their uses while studies.

In heterogeneous system

the eluent passed directly through a U-shaped cell packed with finely devided solid scintillators

including POPOP

poly-naphthalene esters or plastic scintillator.

Such system is suitable for preparative liquid chromatography. The detective efficiency of

3

H and

l4

C were 1.9%

40% respectively. The corresponding limits of detection were 0.1µCi/ml

0.02µCi/ml.

In homogeneous system the eluents were mixed with liquid scintillator by a spiral shaped or U-shaped flow cell

sample used in such system was non-recoverable. And the detective efficency of

3

H and

14

C were 50% and 80%

limits of detection 0.02µCi/ml. 0.001µCi/ml.