Hitachi CHROMASTER 5160 Instruction Manual page 122

(7) Data Check
Determine the coefficient of variation (RSD) of peak
retention time by the following calculations.
Mean value
Standard deviation
Relative standard deviation
xi: Retention time due to each injection
n: Number of injections
Make sure the RSD value is 0.075% or less.
However, this value represents the precision of not the
pump alone but the entire chromatographic system.
Therefore, the value varies with each stability of the
autosampler and detector, accuracy of the data processing
unit and its processing parameters.
4 - 6
n

xi

 i 1
x
n
n
2
 
( xi ) x

i 1

SD

n 1
SD
 
RSD
x
100(%)