A flow injection analysis (FIA lab 2500, USA) was used for the FIA
measurements which is composed of a 4 channel peristaltic pump
and a 6 port 2 way injection valve connected to a Jenway 3510
pH-meter (England); and interfaced to a strip-chart recorder model
BD111 from Kipp and Zonn (Deft, Netherlands). A wall-jet-cell, giving
low dead volume, fast response, good wash characteristics, ease
of construction and compatibility with electrodes of various shapes
and sizes, was used in flow determinations where a Perspex cup
with axially positioned inlet polypropylene tubing is mounted at
0.5 mm from the sensing surface of the electrode body [8,9]. Fig. 1
represents the flow injection setup used in measurements.
Capsule dissolution measurements were made according to the
method provided by the company (Pfizer®) using an Erwika dissolution
device, Germany (USP-type apparatus).