Solid phase extraction (SPE) can be an attractive alternative to
the above-mentioned processes, because it might provide the preconcentration
of the analyte and the discard of interfering agents.
In the traditional SPE concept, the detection will occur on the eluted
phase; however there is a partial loss of preconcentration capabilities
gained in the sorption step . To enhance sensitivity, solid
phase spectrometry (SPS) has been developed based on the direct
measurement of the light attenuation of adsorbent particles packed
in an optical cell, in which the target analyte is concentrated and
coloured . Considering that the measurement occurs without
elution, SPS turns to be a more sensitive method than the conventional
SPE. SPS can be performed by two different approaches:
batch or flow method. To employ the batch method, besides being
very time-consuming, above-average skills are required to pack the
solid particles into the cell. The flow methods are more suitable
since they can easily measure the light attenuation in the adsorbed
species in the flow-through cell with considerable reduction of the
volumes used