while for the
others, it ranged between 90 and 92%. The mean valuewas 89.2%. In
Table 3 results of RSD calculation are shown, which is the measure
of the repeatability. The values of RSD, expressed in percentages as
a ratio of standard deviation to the mean value, ranged between
0.52 and 8.76, while the mean value of RSD was 2.59.