Abstract: Arrangements are described (with diagrams) whereby one spectrophotometric detector can be re-positioned to allow (a) parallel monitoring of several sample zones flowing through different analytical channels or (b) sequential monitoring at different sites within one channel. System (b) can be applied to procedures based on differential kinetics or requiring further processing of a previously analyzed sample. For example, a sample is mixed with all the required solution except the chromogenic reagent and the blank signal is measured at the initial position; the chromogenic reagent is then added and the detector is relocated for measurement further along the channel; the approach can also be used for methods involving standard additions or for determining a potentially interfering species before the sample reaches the site at which the analyte is determined. System (a) was applied to the determination of Fe and Al in plant digests (procedures described) by spectrophotometry at 530 nm after the addition of 1,10-phenanthroline and ascorbic acid reagents (for Fe) and Eriochrome cyanine R - ascorbic acid (for Al). System (b) was used for the sequential determination of Fe(II) (with 1,10-phenanthroline) and Fe(III) (after reduction with ascorbic acid) in natural water. Drawbacks and advantages of each system are discussed. Multi-site detection is achieved when a single detector is allowed to locate at different positions in the manifold. Relocation of the detector is accomplished by connecting its inlet and outlet tubes to strategic manifold sites. The potential and limitations of detector relocation in flow injection spectrophotometry and the influence of the dead volume of the flow cell plus accessories, manifold dimensions and commutation timing are discussed. Anal. throughput is improved with multi-site detection, but the system becomes more sensitive to effects of detector dead volume The feasibility of the approach is demonstrated in the determination of aluminum and iron in plant digests involving parallel monitoring and in the speciation of iron involving serial monitoring.