The FI-CL manifold for the direct determination of Fe(II) with
no preconcentration column is shown in Fig. 1b. This was a simple
manifold in which the sample was loaded into a 180 L loop on
a six-port injection valve (RheodyneTM, Model 5020) and injected
into a 0.001 M HCl carrier stream. This mixed stream merged at
a T-piece with the luminol reagent stream and travelled 3.0 cm
before passing through a quartz glass spiral flow cell (1.1 mm i.d.)
placed directly in front of an end window photomultiplier tube
(Thorn EMI, 9798QA). The photomultiplier tube, quartz flow cell
and T-piece were enclosed in a light tight housing. The photomultiplier
tube was attached to a 1.1 kV power supply (Thorn EMI,
PM20NS) and the detector output was recorded using a chart
recorder (Kipp & Zonen, Delft, The Netherlands). For certain experiments,
an 8-HQ column (shown with dashed lines in Fig. 1b) was
incorporated in the sample stream to remove trace metal cation
interferences.