There is however reason to doubt the stoichiometry of
the reactions because of the different heteropolyanions
that can be formed between Mo and PO43 -. The
reductions are most commonly of 2 electron equivalents
but may be up to 6 electron equivalents. The
reduction evidently occurs on individual Mo atoms,
producing a proportion of Mo v ions. Transfer from
Mo V to Mo vI is then responsible for the intense
'charge transfer' absorption.
Sequential injection analysis (SIA), in contrast to
the classical FIA scheme, relies on preprogrammed
flow reversals rather than on continuous forward flow
[4-9]. Each measurement begins by aspirating a
precisely measured volume of sample so][ution from a