were plotted against the respective concentrations of each
analyte.
The precision of the technique was estimated using
the relative peak area and relative migration time
repeatability for ten consecutive injections of a standard
solution containing 20 mg L−1 of each analyte plus
10 mg L−1 of the internal standard. The intra-day precision
for each analyte was determined by assaying three control
samples at low, medium, and high concentrations using
triplicate injections on the same day.