Performance of annular membrane and screen-tee reactors for postcolumn-reaction detection of metal ions separated by liquid chromatography

TLDR: In this paper, the experimental factors that contribute to base line noise in the postcolumn-reaction detection of metal ions eluted from high-performance dynamic ion exchangers have been evaluated and compared for a screen-tee reactor and three annular membrane reactions having internal volumes of 1.5, 5.3 and 9.6

Abstract: The experimental factors that contribute to base line noise in the postcolumn-reaction detection of metal ions eluted from high-performance dynamic ion exchangers have been evaluated and compared for a screen-tee reactor (approx. 1 ..mu..L internal volume) and three annular membrane reactions having internal volumes of 1.5, 5.3, and 9.6 ..mu..L. Measurements of mixing homogeneity, performed with pulseless gas-pressure pumping, showed that both reactor designs gave a mixing homogeneity that was 99.983% of that theoretically possible (perfect mixing) for two solutions differing in absorbance by 2.38 units. For normal operation with high-performance reciprocating pumps for eluent delivery, pump pulsations were responsible for 90-100% of the observed peak-to-peak noise. Column efficiency measurements with a series of lanthanide metal ions gave similar curves for both designs (HETP values of 0.01-0.04 mm). Both reactors gave reproducible peak areas, had good peak shapes, and operated reliably. With the membrane reactors some leakage of eluent into the reagent solution occurred at high eluent or reagent flow rates, but this was not a problem for normal operating conditions.