Biohit Proline - Page 15

7. Pipette the water into the weighing vessel, touching the tip against
the inside wall of the vessel just above the liquid surface at an
angle of 30° to 45°. Withdraw the pipettor by drawing the tip 8-10
mm along the inner wall of the weighing vessel.
8. Read the weight in mgs (m
i
).
9. Repeat the test cycle until 10 measurements have been recorded.
10. Convert the recorded masses (m
i
) to volumes (V
i
)
V
i
= m
i
Z Z = correction factor (Table 1)
11. Calculate the mean volume (V) delivered:
V = (∑V
i
)/10
12. For conformity evaluation calculate the systematic error e
s
of the
measurement:
in µl: e
s
= V – V
s
V
s
= selected test volume
or in %: e
s
= 100 (V – V
s
)/V
s
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 coefficient of variation CV = 100S/V
14. Compare the systematic error (inaccuracy) and random error
(imprecision) with the values in the performance specifications
(pages 48, 49), or the specifications of your own laboratory.
If the results fall within the specifications, the pipettor is ready for
use. Otherwise check both systematic and random errors and,
when necessary, proceed to the recalibration procedure
(Chapter 8.2).
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 specifications are achieved in strictly controlled conditions
(ISO 8655-6). The user should establish own specifications based on
the field of use and the accuracy requirements placed on the pipettor
(ISO8655-1).
Table 1
Note: This method is based on ISO 8655.
43
Z-values (µl/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