13
13. For conformity evaluation calculate the random error of the
measurement:
as standard deviation s =
∑
(V
i
-
v
̄
)
2
n = number of
measurement (10)
n - 1
or as coef
fi
cient of variation CV = 100
s
/
v
̄
14. Compare the systematic error (inaccuracy) and random error
(imprecision) with the values in the performance speci
fi
cations
- (p. 49) or the speci
fi
cations of your own laboratory.
If the results fall within the speci
fi
cations, the pipette is ready
for use. Otherwise check both systematic and random errors
and, when necessary, proceed to the recalibration procedure
(Chapter 12.2).
Note
: Systematic error (inaccuracy) is the difference between the
dispensed volume and the selected test volume. Random error
(imprecision) is the scatter of the dispensed volumes around the
mean of the dispensed volume. (ISO 8655-1.)
Note
: Biohit speci
fi
cations are achieved in strictly controlled condi-
tions (ISO 8655-6). The user should establish own speci
fi
cations
based on the
fi
eld of use and the accuracy requirements placed on
the pipettor (ISO8655-1).
Table 1
Note:
This method is based on ISO 8655.
Z-values
(
μ
l/mg):
Temp. (°C)
Air Pressure (kPa)
95
100
101.3
105
20.0
1.0028
1.0028
1.0029
1.0029
20.5
1.0029
1.0029
1.0030
1.0030
21.0
1.0030
1.0031
1.0031
1.0031
21.5
1.0031
1.0032
1.0032
1.0032
22.0
1.0032
1.0033
1.0033
1.0033
22.5
1.0033
1.0034
1.0034
1.0034
23.0
1.0034
1.0035
1.0035
1.0036
23.5
1.0036
1.0036
1.0036
1.0037
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