Purpose:
To develop and validate a user-friendly spiked plasma
method for the extraction of diclofenac potassium that
reduces the number of treatments with plasma sample, in
order to minimize human error.
Method:
Instead of solvent evaporation technique, the spiked
plasma sample was modified with H2SO4
and NaCl, respectively, and then the drug was extracted
after vortexing the sample with acetonitrile as
precipitating agent. The separation of diclofenac
potassium and internal standard (ketoprofen) was
achieved at preset conditions: 5 μm ODS Hypersil C-18
(4.0 mm x 250 mm) column, eluted with 50% acetonitrile
in water (v/v) as mobile phase containing ammonium
acetate and triethylamine (TEA), at a flow rate of 1 mL
min-1.
Results:
The peaks of the drug and internal standard (I.S.) were
resolved at 14 ± 1 min and 7 ± 1 min, respectively. The
calibration curve and linearity were determined over the
concentration range of 0.25 to 40 µg mL-1 and
they were linear (r2 = 0.9991 and 0.9982,
respectively). The accuracy was > 81.32 %. Limit of
detection and limit of quantification were 0.05 and 0.25
µg mL-1, respectively, while the
recovery range for diclofenac potassium and ketoprofen
was more than 79 and 85 %, respectively. The absolute
average difference of 0.18 between the observed
concentrations for intra- and inter-day studies
indicated that the sample was stable for over one month.
Conclusion:
The proposed method may be applied to routine
bioanalysis, particularly for NSAIDs, due to its high
sensitivity, specificity, repeatability,
reproducibility, robustness and ruggedness.
Keywords:
Bioanalytical method, Diclofenac potassium, RP-HPLC
method, NSAIDs, Plasma
