Jj. Pedrotti et al., A FAST, HIGHLY EFFICIENT, CONTINUOUS DEGASSING DEVICE AND ITS APPLICATION TO OXYGEN REMOVAL IN FLOW-INJECTION ANALYSIS WITH AMPEROMETRIC DETECTION, Analytica chimica acta, 298(3), 1994, pp. 393-399
A new continuous degassing device, based on the permeation of gases di
ssolved in a liquid through the walls of a narrow-bore polymeric tube,
is described. The key innovation, responsible for the sueerior effici
ency in relation to other designs, consists in maintaining a reduced p
ressure of an inert gas (N-2, ca. 1600 Pascal) in the degassing chambe
r that contains the coiled polymeric tube wandered by the solution. Wh
en applied to the continuous removal of oxygen from an electrolyte in
flow-injection analysis, FIA, with amperometric detection (flow of 1.0
ml/min, 34 s residence time), a decrease of at least 99.97% in the ox
ygen reduction current is experienced. Routine determination of 80 sam
ples per hour of heavy metals like cadmium is afforded with a detectio
n limit of about 10 ppb (1.8 x 10(-12) mol of Cd(II) for 20-mu l injec
tions), by using a sessile drop mercury electrode. FIA with pre-concen
tration followed by voltammetric stripping extends the detection limit
to the sub-ppb level, as illustrated by monitoring lead and cadmium i
n samples of drinking water.