Table 3: Evaluation of intra-day and inter-day precision and accuracy.

Method STS* takenIntra-day ( )Inter-day ( )
STS founda%RSDb%REcSTS founda%RSDb%REc

A
(Titrimetry)
4.003.980.900.553.951.391.21
6.005.990.920.236.041.090.65
8.008.050.730.59 8.061.060.76

B
(Spectrophotometry)
6.006.060.970.966.081.831.42
9.009.101.041.069.121.571.32
12.011.91.020.9411.91.401.12

C
(Spectrophotometry)
1.001.021.441.551.022.201.93
2.001.980.941.141.971.371.40
3.002.970.630.852.970.911.02

In method A, STS taken/found are in mg and they are μg mL−1 in methods B and C.
aMean value of five determinations.
bRelative standard deviation (%).
cRelative error (%).