Equipment maintenance and calibration checks
Guideline
Purpose and use of this guideline document
Where there is a requirement for the analysis or evaluation of clinical trial samples to be performed to
GCP standards, all equipment used for the storage, handling, analysis and disposal of samples must
be adequately tested, calibrated, serviced and maintained.
This document provides guidelines for how this can be approached in general, and also describes
calibration procedures for specific types of instruments in common use. It can be used for the
development and implementation of trial- and/or laboratory-specific written procedures.
Record keeping
 Records of equipment service, maintenance and calibration must be maintained and available
for inspection. Example forms are available and are referenced where appropriate in the body
of this document below.
 All records must be stored safely and securely throughout the trial and archived with the other
trial documents when the trial closes.
Developing written procedures
You are advised to include the following:
 A description of the piece(s) of equipment covered.
 The name or job title of the person(s) responsible for carrying out the procedures and the
maintenance and storage of records (it is recognised that routine servicing and calibration
checks are often carried out by equipment manufacturers under service contracts, and
records are kept centrally by Technical Managers).
 Procedures developed from the guidelines below.
Adverse events
You are strongly advised to consider the actions to be taken should a piece of equipment fail, or fail a
calibration check, and what impact this may have on sample integrity or analysis.
The failure of the equipment and the repairs to be carried out should be recorded, as should the
impact assessment.
Other guideline documents and example forms are available to help with the development of specific
procedures for adverse events and the records associated with this (see UoB-CLN-LAB-QCD-010
Impact assessment of equipment failure or equipment calibration failure, UoB-CLN-LAB-QCD-016
Adverse Events in the analytical laboratory, UoB-CLN-LAB-QCD-019 Procedures following failure of
storage unit, UoB-CLN-LAB-QCD-021 Equipment maintenance record, UoB-CLN-LAB-QCD-029
Impact assessment of equipment failure of equipment calibration failure and UoB-CLN-LAB-QCD-032
Adverse Event report).
General guidelines
New equipment
 Ensure that new equipment is tested and only released for use when it is performing
adequately.
Labelling of equipment
 Assign a unique ID number to each piece of equipment and label the equipment clearly with
this number.
 Label equipment with the date when the next routine service or calibration check is due.
 Label any uncalibrated equipment as such.
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Guideline
 If a piece of equipment fails, fails a calibration check or becomes otherwise unfit for use, label
with ‘Out of Use’.
Deciding on service, maintenance and calibration check requirements
 Assess this jointly with Technical Manager(s), manufacturers, or expert users of the
equipment.
 Base on the manufacturer’s recommendations, use of the equipment, stability of
measurement and the consequences of the equipment failing or being found outside
acceptable calibration.
Calibration checks
 Identify an acceptable range of results for a particular instrument.
 Use a recognised national or international reference standard where possible, or a standard
that has documented traceability to a national/international reference standard.
 For instruments that are normally calibrated with each use (e.g. pH meters, osmometers,
HPLCs, some scanners, sequencers), record the ‘as used’ calibrations as part of the
analytical detail recorded.
Record keeping
 Consider setting up a separate Equipment maintenance record for each piece of equipment
(for an example form see UoB-CLN-LAB-QCD-021 Equipment Maintenance Record).
 Record all routine service, maintenance and calibration checks.
 Date and initial all entries.
 If an item of equipment fails, or fails a calibration check, record this information together with
details of repairs.
 If routine maintenance or calibration is missed for any reason, indicate this on the records with
a statement such as ‘not taken’ or ‘not carried out’ so that the record is not left blank.
Instructions for calibration checks
Air-displacement pipettes
Air-displacement pipettes require calibration checks to ensure that the volumes dispensed are
accurate. It is recommended that pipette function checks, seal checks and calibration checks are
carried out at least once every 6 months (or more regularly if failures occur).
It is common practice for air-displacement pipettes to be checked and calibrated by pipette specialists
or manufacturer or equivalent and records/certificates should always be kept. However it is also
possible for this to be carried out ‘in house’. Consider following the instructions below and develop a
written procedure accordingly. Example forms are available (see UoB-CLN-LAB-QCD-022 Single
channel pipette calibration check record and UoB-CLN-LAB-QCD-023 Multi channel pipette
calibration check record).
General points
1. Pipettes used to dispense volumes of 10μl or less should not be calibrated ‘in house’.
2. It is strongly recommended that all pipettes should be stored vertically on a dedicated stand
between uses.
Pipette function and seal check
1. Check the pipette for signs of damage and poor action, no damage should be apparent and the
pipetting action should be smooth.
2. Attach a clean tip securely to the pipette.
3. Draw up into the pipette tip the maximum volume handled by the pipette.
4. Suspend the pipette vertically, tip downward for 1 minute.
5. Observe for droplet formation from the tip(s).
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6. If a drop forms then the pipette should be cleaned and the seals replaced as necessary.
7. Record details of pipette function and seal check.
‘In house’ calibration check (single channel pipettes)
1. Ensure the balance used is level and within calibration.
2. Each pipette should have a new record for each calibration check.
3. Set the volume on the pipette according to the pipette size, as shown in Table 1 below.
4. Firmly attach a clean tip to the pipette.
5. Pipette and discard two volumes to wet the pipette tip.
6. Pipette distilled or deionised water (at ambient temperature) into a tared weighing boat on the
balance. Record the weight of the volume and repeat until 10 volumes have been dispensed (zero
the balance between each volume). Work as quickly as accuracy allows in order to reduce the
evaporative loss of water.
7. Any dispensing operation where water is seen to be retained in the tip (i.e. pipetting error) may be
rejected and replaced with an additional weight.
8. Calculate and record the mean dispensing weight. This should be within the range specified in
Table 1 below.
9. Each individual accepted weight should be in the range of +/- 10% of the mean dispensing weight.
10. If the mean dispensing weight and the individual weights are inside the specified range, the
pipette is acceptable for use.
11. If the mean dispensing weight and any individual weight are outside the specified range, the
pipette should be re-checked up to a total of three times:
o The pipette is acceptable if the individual and mean weights obtained from two out of
three checks are within the specified ranges
o The pipette is unacceptable if the individual and mean weights obtained from two out of
three checks are outside the specified range
12. If the pipette is acceptable, re-label it with the next “calibration check due” date.
Table 1
Pipette ranges
Set volume
Specified range
weight of water *
10 - 20 l
20 l
19.7 - 20.3 mg
10 - 50 l
20 l
19.7 - 20.3 mg
10 - 100 l
50 l
49.6 - 50.6 mg
50 - 200 l
100 l
99.2 - 101.2 mg
20 - 500 l
250 l
248.6 - 252.6 mg
200 - 1000 l
500 l
496 - 506 mg
1000 - 5000 l
2000 l
1985 - 2026 mg
* This value has been corrected for deionised water at 18.5°C and 907 mbar air pressure (Z =
1.0025). It is to be used for calibration checks undertaken within the temperature range 12.0 - 25.0°C.
‘In house’ calibration check (multi channel pipettes)
1. Ensure the balance used is level and within calibration.
2. Each pipette will have a new record for each calibration check.
3. Place a fresh tip firmly on each channel of the pipette.
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4. Draw the liquid up into the tips, hold the pipette vertically and observe the level of the liquid in the
tips:
o If the liquid level is uniform across the tips proceed to the next section.
o If the level is different between tips then the pipette requires repair.
5. Set the volume according to Table 1 above.
6. Pipette distilled or deionised water (at ambient temperature) from all channels simultaneously into
a tared vessel. Record the weight of the volume and repeat until 10 volumes have been
dispensed (zero the balance between each volume).
7. Record the volume dispensed from each channel by using the following calculation:
Mean weight of water per channel (mg)
=
Total weight of water (mg)
10 x number of channels
8. The mean weight should be in the range specified in Table 1.
9. If the mean weight is outside the specification range the pipette should be rechecked up to a total
of three times:
o If two means are within specification the pipette is acceptable
o If two means are outside specification then the pipette is unacceptable
10. Each time a multi channel pipette fails a calibration check the information must be recorded on the
calibration record together with details of repairs.
11. If the pipette is acceptable, re-label it with the next “calibration check due” date.
Thermometers and temperature probes
Uncertified thermometers and temperature probes are commonly used to monitor temperature
controlled equipment. Some electronic temperature probes or logging devices may be calibrated and
certified externally and records/certificates should always be kept, however it is very likely that some
will require in-house calibration checks.
An example form for recording calibration checks of thermometers and temperature probes is
available (see UoB-CLN-LAB-QCD-024 Thermometer and temperature probe calibration check
record).
Note: Some fridges or freezers may have more than one temperature monitoring probe, for example,
there may be an electronic pre-installed probe, and there may be a temperature probe sited within the
freezer which is linked to monitoring software/dial-out alarms etc. It is vital to make it clear which
probe is being used as the primary temperature monitor; wherever possible this should be the probe
connected to the dial-out alarm system.
Calibration check
1. Uncertified electronic thermometers and temperature probes require a calibration check
against a certified reference thermometer each calendar year and non-electronic
thermometers require a calibration check every five years.
2. Certified reference thermometers (electronic or otherwise) must be sent to an accredited
calibration facility for recertification every calendar year.
3. If thermometer/probe calibration checks are being carried out within the cold room ensure the
door is fully closed.
4. During calibration checks in a water bath/beaker of water, immerse the certified thermometer
to the extent required by the individual device, and immerse the test thermometer or probe to
the extent marked on the individual device or inferred by the device literature.
5. Where heated water baths are used, turn off the heater to read the thermometers to reduce
the differential time responses to temperature change that may occur between the test and
reference thermometer.
6. Always allow temperature readings to equilibrate for 30 minutes or until the temperature readouts are seen to be stable.
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7. Record the actual temperature reading of both the certified thermometer, and the in-use
thermometer or probe.
8. Following a successful calibration check label the equipment with the date when the next
routine calibration check is due.
9. Acceptable readings are:
– 70C
or colder
+ 5C
– 20C
or colder
+ 3C
+ 37C
+ 1C
+ 4C
to
Laboratory balances
Balances should be labelled clearly with the ‘working’ range. An example form for recording
calibration checks of laboratory balances is available (see UoB-CLN-LAB-QCD-025 Balance
calibration check).
Calibration check
1. Balances should be checked using a set of certified weights (directly traceable to national
standards) once every month.
2. These certified weights should be sent to be recertified to national standards every two years.
3. For all balances three different weights should be used which reflect the weighing range of the
balance (ideally at the upper, lower and middle of the ‘working’ range for each balance).
o Weights must not be handled directly.
o For larger weights wear cotton or similar gloves (no powdered gloves) and use forceps for
small weights.
4. The table below shows the reference weights available and the range of acceptable readings.
Reference weight
(g)
Acceptable range (g)
0.001
0.00095 - 0.00105
0.05
0.0495 - 0.0505
1
0.99 - 1.01
10
9.9 - 10.1
100
99 - 101
500
498 - 502
1000
999-1001
2000
1998 - 2002
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Related documents
 UoB-CLN-LAB-SOP-001 Procedures for GCP compliance in the laboratory
 UoB-CLN-LAB-QCD-010 Impact assessment of equipment failure or equipment calibration
failure
 UoB-CLN-LAB-QCD-016 Adverse events in the analytical laboratory
 UoB-CLN-LAB-QCD-019 Procedures following failure of storage unit
 UoB-CLN-LAB-QCD-021 Equipment maintenance record
 UoB-CLN-LAB-QCD-022 Single channel pipette calibration check record
 UoB-CLN-LAB-QCD-023 Multi channel pipette calibration check record
 UoB-CLN-LAB-QCD-024 Thermometer and temperature probe calibration check record
 UoB-CLN-LAB-QCD-025 Balance calibration check record
 UoB-CLN-LAB-QCD-029 Impact assessment of equipment failure or equipment calibration
failure report
 UoB-CLN-LAB-QCD-032 Adverse event report
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