Recalibration - VWR UHP Mode D'emploi

CAUTION: Aspiration differences can be avoided if the
pipetting operation is conducted slowly, so that the liquid
can slowly adjust to the changing pressure. Wait for
about 2 seconds after each aspirating and dispensing,
without changing the position of the pipettor.
If the above procedure does not provide accurate
results, pipettor recalibration is required according to
section 5.
After calibration, it is recommended to record recalibration
and the adjustment value, which will facilitate return cali-
bration to the standard liquid.

5. RECALIBRATION

VWR UHP pipettors are calibrated by gravimetric method,
using VWR tips and distilled water, at the temperature
20°±1°C, according to EN ISO 8655 standard.
It is recommended to conduct periodic inspection of the
pipettor operation, with the interval between inspections
being dependent on the type of load (aspirated liquids)
and other conditions (load intensity and autoclave sterili-
zation, replacement of subassemblies) in which the
pipettor is used.
The pipettor recalibration procedure should be carried
out if during the pipettor operation you find that the accu-
racy error (the difference between the real aspirated vol-
ume and the preset volume) exceeds the permissible
value given in Table 1.
Checking the pipettor parameters
To determine accuracy error of the pipettor, the following
requirements must be fulfilled:
• The ambient temperature of the pipettor, tips and the
test liquid (typically distilled water) should be within the
range of 20-25°C and stabilized during weighing within
the range ±0.5°C,
• The density of the liquid used should be close to that of
distilled water,
• The balance sensitivity should be appropriate to the
tested volume (Table 2),
• The [mg/μl] conversion factor, dependent on temperature
and pressure, should be taken into account (Table 3).
9
Volume [μl]
Balance sensitivity [mg]
Table 2
Temperature [°C]
20
21
22
23
24
25
Table 3
CAUTION: The pipetting procedure should be conducted
in accordance with the rules described in sections 3 and 4.
Recalibration procedure:
• Set the dose volume depending on the pipetted volume
according to Table 4.
Model
volumes [μl]
VWR ME-10, VWR MT-10
VWR ME-50, VWR MT-50
VWR ME-200, VWR MT-200
VWR ME-300, VWR MT-300
Table 4
• Perform 5 aspirations, weigh each one and calculate
the average value of the aspirations.
• Calculate average aspirated volume in [μl] by multiplying
the average aspiration amount [mg] by the distilled
water density coefficient [μl/mg], which depends on
temperature and pressure (Table 3).
• If the average aspirated volume exceeds the permissi-
ble values, pipettor recalibration should be conducted.
Pipettor recalibration consists in setting the real value
obtained during weighing on the counter. To do so, the
following should be conducted:
ENGLISH
0.1 - 10 10 - 100 > 100
≤ ≤ ≤
0.001 0.01 0.1
Pressure [kPa]
95 101.3 105
1.0028 1.0029 1.0029
1.0030 1.0031 1.0031
1.0032 1.0033 1.0033
1.0034 1.0035 1.0036
1.0037 1.0038 1.0038
1.0039 1.0040 1.0040
Range
Preset Permissible
of the
volume volumes
pipettors
[μl] [μl]
1-10 1 0.92-1.08
5-50 5 4.8-5.2
20-200 20 19.4-20.6
50-300 50 49.2-50.8
10