Stability studies
Various stability study was carried out. Room temperature
stock solution stability, refrigerated stock solution
stability, freeze thaw stability, short term stability and
long term stability were determined. Room temperature
stock solution stability was carried out at 0, 3 and 8 hoursby injecting four replicates of prepared stock dilutions of
Clindipine equivalent to middle quality control sample
concentration and the stock dilution of internal standard
equivalent to the working concentration. Comparison of
the mean area response of Clindipine and internal
standard at 3 and 8 hours was carried out against the zero
hour value. Refrigerated stock solution stability was
determined at 7, 14 and 27 days by injecting four
replicates of prepared stock dilutions of the analyte
equivalent to the middle quality control sample
concentration and the stock dilution of internal standard
equivalent to the working concentration. The stability
studies of plasma samples spiked with Clindipine were
subjected to three freeze - thaw cycles, short term stability
at room temperature for 3 h and long term stability
at 70oC over four weeks. In addition, stability of standard
solutions was performed at room temperature over 6 h
and after freezing for four weeks. The stability of
triplicate spiked human plasma samples following three
freeze thaw cycles was analysed. The mean concentrations
of the stability samples were compared to the
theoretical concentrations. The stability of triplicate short
term samples spiked with Clindipine was investigated at
room temperature for 1.00 to 3.00 h before extraction.
The plasma samples for long term stability were stored in
the freezer at -70oC until the time of analysis.