3.2. Validation of the analysis method
The proposed HPLC method was validated under isocratic condition
in terms of linearity, detection limit, precision, repeatability
and stability. The standards have different UV response factors, to
determine their relative amounts, X2 was selected as the
reference compound for calculated the relative response factors
(RRFs). The RRFs for X2–X6 were calculated as a peak area ratio
of the each compound to the reference in the concentration of
5 mg/mL, and the results were listed in Table 1. The linearity
was verified by the analysis of nine points in the range of
0.05–10 mg/mL of standard sugars (X2–X6), and the linear regression
parameters of the calibration curves were shown in Table 1.
The residual standard deviations (r) of the regression curves for
X2–X6 were in the range of 0.17–0.58 mg/mL. The linear correlation
between the peak area (Y, mAu min) and the concentration
(X, mg/mL) of each sugar standard was excellent. The limits of
detection at the signal-noise ratio (S/N) of 3 were determined to
be 0.22–0.48 lg/mL by successive dilutions of PMP-labeled
X2–X6 standards mixture.