Fig. 1 depicts the set-up of the measuring
flow system used. A flow through cell was fabricated
from 6×4 cm polyacrylamide plates and mounted in place of a
sample cell of the spectrophotometer for flow absorption measurements.
An agarose membrane sensor and a rubber film, with
a 1×3 opening, were sandwiched between the two polyacrylamide
plates. The plates were held together with four screws. A
peristaltic pump (EYLA, Japan)was used for pumping solutions
through the flow cell, usually with a flow rate of 5mL min−1. A
rotating valve was used for switching between samples.