US Environmental Protection Agency
Office of Pesticide Programs
Office of Pesticide Programs
Microbiology Laboratory
Environmental Science Center, Ft. Meade, MD
Standard Operating Procedure for
Verification of Digital Pipettes
SOP Number: QC-19-10
Date Revised: 02-01-19

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SOP No. QC-19-10
Date Revised 02-01-19
Page 1 of 6
SOP Number
QC-19-10
Title
Verification of Digital Pipettes
Scope
Describes the process for verification of digital pipettes.
Application
Pipettes are calibrated by an ISO 17025 accredited vendor at a
frequency determined by the laboratory and are verified in-house
using the gravimetric procedure as necessary.


Approval Date
SOP Developer:

Print Name:
SOP Reviewer

Print Name:
Quality Assurance Unit

Print Name:
Branch Chief

Print Name:


Date SOP issued:

Controlled copy
number:

Date SOP withdrawn:


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SOP No. QC-19-10
Date Revised 02-01-19
Page 2 of 6
TABLE OF CONTENTS
Contents	Page Number
1.
DEFINITIONS
3
2.
HEALTH AND SAFETY
3
3.
PERSONNEL QUALIFICATIONS AND TRAINING
3
4.
INSTRUMENT CALIBRATION
3
5.
SAMPLE HANDLING AND STORAGE
3
6.
QUALITY CONTROL
3
7.
INTERFERENCES
3
8. NON-CONFORMING DATA
3
9.
DATA MANAGEMENT
3
10.
CAUTIONS
3
11.
SPECIAL APPARATUS AND MATERIALS
4
12.
PROCEDURE AND ANALYSIS
4
13.
DATA ANALYSIS/CALCULATIONS
6
14.
FORMS AND DATA SHEETS
6
15.
REFERENCES
6

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SOP No. QC-19-10
Date Revised 02-01-19
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1. Definitions
Abbreviations/definitions are provided in the text.
1.	Verification failure = Verification of pipette exceeds ±5% inaccuracy
and/or <5% of the coefficient of variation (% CV).
2.	Ideal volume = Target volume; actual volume being measured, corrected
for temperature using the density of water at 21.0°C (0.997995 g/mL, see
section 15.1).
3.	Percent inaccuracy = percentage by which measured volume differs from
the target volume
2. Health and
Safety
Follow procedures specified in SOP MB-01, Laboratory Biosafety.
3. Personnel
Qualifications
and Training
Refer to SOP ADM-04, OPP Microbiology Laboratory Training.
4. Instrument
Calibration
1.	The pipets are calibrated by an ISO accredited vendor or verified in-house
(refer to section 12.2) on a predetermined frequency (see the Pipette
Verification Record Sheet, section 14).
2.	Refer to SOP EQ-03 (weigh balances) for details on method and
frequency of calibration.
5. Sample
Handling and
Storage
None.
6. Quality Control
For quality control purposes, the required information is documented on the
appropriate form(s) (see section 14).
7. Interferences
1. Pipettes with inaccuracies that exceed the specifications listed in this SOP
(see section 8.2).
8. Non-
conforming
Data
1.	Manage non-conforming data consistent with SOP ADM-07, Non-
Conformance Reports.
2.	Do not use pipettes if the inaccuracy exceeds ±5% of the target volume
and/or <5% CV (see 13.1). For corrective actions, see section 12.3.
9. Data
Management
1.	Archive data consistent with SOP ADM-03, Records and Archives.
2.	Maintain an inventory of pipettes electronically using a Microsoft Excel
spreadsheet (refer to section 14). After each addition to or deletion from
the inventory, file a hard copy of the pipette inventory in the Pipette
Verification and Calibration Record Book.
10. Cautions
1. If a pipette fails an in-house verification assessment, do not use it until it
has been repaired (if necessary) and recalibrated by an ISO 17025

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SOP No. QC-19-10
Date Revised 02-01-19
Page 4 of 6
accredited vendor (see 12.1b).
11. Special
Apparatus and
Materials
1.
2.
Calibrated balances. Capable of measuring 0.01 g for verifying pipettes
with volumes greater than 1 mL and 0.0001 g for verifying pipettes with
volumes less than or equal to 1 mL.
a.	For balances capable of measuring up to 0.00001 g, use the upper
weight range of the balance in order to display a resolution of 0.0001
g prior to initiating gravimetric pipette verification procedure.
Pipettes.
b.	Rainin Adjustable Volume Pipettes
Gilson Microman Positive Displacement Pipettes
c.
d.
Gilson Distriman Continuously Adjustable Volume Repetitive
Pipettes
e. Eppendorf Repeater Pipettes
12. Procedure and
Analysis
12.1
Pipette
Verification
Requirements
a.	Verify and service pipettes using an ISO 17025 accredited vendor;
refer to the Pipette Verification Record Sheet (see section 14) for the
frequency of verification.
b.	If a pipette is dropped or broken, verify the pipette using the
gravimetric verification procedure (see section 10).
c.	Record vendor or in-house verification results on the Pipette
Verification Record Sheet (refer to section 14) and file in the Pipette
Verification and Calibration Log Book. The Pipette Verification
Record Sheet is based on the inventory of pipettes and may change
over time.
12.2 Gravimetric
Verification
Procedure
The gravimetric pipette verification procedure utilizes the relationship
between the weight of a water sample (g) and its density (g/mL) to verify the
volume being delivered at a specified temperature.
a.	Use the pipette tips that correspond to each pipette.
b.	Record all pertinent information for the gravimetric verification
procedure on the Pipette Verification - Gravimetric Analysis Form
(refer to section 14).
c.	In advance of testing, fill a container with de-ionized water and allow
it to equilibrate to room temperature in the same laboratory as the
balance. List the balance that will be used on the appropriate form.

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SOP No. QC-19-10
Date Revised 02-01-19
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d.	Place a small container on the balance (for example, a 50 mL
Erlenmyer flask) and record its weight on the appropriate form.
e.	Using the pipette to be verified, aspirate an aliquot of DI water from
the sample aliquot container and dispense into the small container.
Refer to the Pipette Verification - Gravimetric Analysis Spreadsheet
(see section 14) for the recommended verification volume for each
pipette.
f.	Record the weight on the appropriate form.
g.	Follow the procedure in 12.2d-e for each subsequent sample
addition; measure at least 5 samples. Do not tare between samples.
After each new sample addition, record the weight on the appropriate
form.
h.	Input the measurements and other appropriate information into the
pipette-specific worksheet in the Pipette Verification - Gravimetric
Analysis Spreadsheet (see section 14).
i.	Verify that the percent inaccuracy is within ±5% and the % CV is
<5%.
i.	If either the percent inaccuracy or % CV are outside the
required range, repeat the analysis.
ii.	If the ranges continue to be outside the required range, label
the pipette as "Out of Service" and remove the pipette from
use until it is repaired and calibrated by a vendor.
12.3 Pipette
Verification
Record Sheet
a.	From the data on the calibration certificate or Pipette Verification -
Gravimetric Analysis Spreadsheet for each pipette, record the
following on the Pipette Verification Record Sheet:
i.	Verification Status: record as "pass" or "fail." Record status
as "pass" if the percent inaccuracy is within ±5% and the %
CV is <5% from gravimetric analysis or if vendor calibration
certificate indicates acceptable results, otherwise record as
"fail."
ii.	Corrective Action: record as "yes" or "no." If the verification
status is "pass," record as "no." Record as "yes" if the
verification status is "fail," describe the action taken at the
bottom of the page, and notify the Quality Assurance Officer
(QAO). The QAO must determine if there was any impact on
work conducted using the failed pipet.
b.	Complete the Pipette Verification Record Sheet electronically or by

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SOP No. QC-19-10
Date Revised 02-01-19
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hand.
13. Data Analysis/
Calculations
„ , . (x-ideal volume)x 100
1. Percent Inaccuracy = -			
ideal volume
° n/ CV fStandard deviation's w -^qq
\ Mean J
14. Forms and Data
Sheets
1. Test Sheets. Test sheets are stored separately from the SOP under the
following file names:
MLB Pipette Inventory QC-19-10 Fl.xlsx
Pipette Verification Record Sheet QC-19-10_F2.xlsx
Pipette Verification - Gravimetric Analysis Form QC-19-10 F3.xlsx
Pipette Verification - Gravimetric Analysis , „ , „ . ,
c , , A QC-19-10 F4.xlsx
Spreadsheet -
15. References
1. CRC Handbook of Chemistry and Physics. 93rd ed. CRC Press: Boca
Raton, FL, 2012; p 6-8.

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