New Technological Guidelines
Required for Pipette Management(Proposal of a Pipette Management Method)R&D Division 5
A&D Company, Limited
2010/9/2

First of All
Differences in dispensing volume of pipettes► Directly influence the test results
Compliance with standards such as GLP or GCP► For creating a SOP (Standard OperatingProcedure), checking pipette performance
Problems in the workplace► Avoiding troubles due to pipette inaccuracy► Maintaining and controlling pipette performancePipette Management Tools
Pipette Leak Tester

AD-1690

AD-4212B-PT
AD-4212A-PT

Pipette Accuracy Testers

FX-300i-PTPipette Structure (Air-displacement Type)Tip

Tip holder

O-ringPistonSeal

What Is a “Leak?”• Fissures/scratches on the tipholder• Deterioration of the O-ring• Abrasion/scratches of the seal
• Rust on the piston, etc.

Unable to maintain the airtightness when moving the piston=> Unable to aspirate the set volume into the tip

Decreased dispensing volume from the pipetteGeneral Leak Detection Method• Aspirate water and leave it. Check
whether a ball of water appears at the tipend.
• Aspirate water and dip the tip end into
the water container. Check whether thewater level inside the tip lowers.

Aspirate • Leave

LeakBall ofwater
Aspirate • Leave

Visual check• Difficult to make judgments with consistentcriteria• Some leaks may be missed depending on
the degree of the leak.

Leak

Checking Pipettes Using the Leak Tester• Actively reproduces the negative pressure that arises insidethe pipette• Detects leakage by monitoring pressure variation after thenegative pressure is generated• Prevents contamination (ingress of dust inside the pipette)by using the depressurization method
Air filter unit
(Inside: air filter element)

DepressurizationBottom sideHow the Leak Tester Operates
Leak Tester Operation (Example of Pressure Variation and Judgment)Benefits of Management With the Leak Tester

Easy (no water required), quick (approx. 6 sec.), andjudgment using uniform criteria

Possible to detect pipette leaks
efficiently as a daily task

Leak-test Results and Necessary Actions• Pipette with leakage

LeakageUnable to dispense the set volume

Leak test

No leakage

Maintenance required
FailPerformance check bygravimetric method• Pipette without leakage
Not always able to dispense
the set volume

PassMaintenance

Performance check bygravimetric method

UsableCorrelation Between Leak Amounts andDispensed Volumes
Correlation Between Leak Amounts and Dispensed Volumes(Set Volume: 200 µL)

Performance Check by Gravimetric Method
Measure the mass of the distilled water dispensed from thepipette and then convert it to a volume.
• ISO 8655(2002)
ISO 8655-2： Piston pipettes (specificationsrequirements)
ISO 8655-6： Gravimetric methods for thedetermination of measurement error• JIS K0970(1989)* Distilled water is a standard substance with known properties* ISO 8655 is commonly practiced.

Mass-to-volume Conversion (ISO 8655
Gravimetric Method)
The mass of the distilled water dispensed from the pipette ismultiplied with a conversion factor called Z factor to obtain thevolume.
Vi = mi × Z
Vi : Volume(μL)
mi : Mass of the distilled water (mg)
Z : Z factor (conversion factor, μL/mg)“Z factor”
Factor to calculate a volume from a mass of distilled water, taking the temperatureof the distilled water and the atmospheric pressure as parameters
The following are taken into account:• Density based on the water temperature• Buoyancy of the distilled water (from atmospheric pressure and temperature)

Influences of Water Temperature andAtmospheric Pressure• Influence of water temperature
Approx. 0.1% per change of 5 ˚C between 15 ˚C and 30 ˚C• Influence of atmospheric pressure
Approx. 0.005% per change of 50 hPa between 850 hPa and 1050 hPa
Z factor matrix shown by ISO8655 (extract)
Temp
˚C
15.0
15.5
16.0
16.5
17.0
17.5
18.0
18.5
19.0
19.5
20.0
20.5
21.0
21.5

800
1.00171.00181.00191.00201.00211.0022
1.0022
1.00231.00241.00251.00261.00271.00281.0030850
1.00181.00191.00201.00201.00211.0022
1.00231.00241.00251.00261.00271.00281.00291.0030Atmospheric pressure
hPa
900
950
1000
1.00191.00191.00201.00191.00201.00201.00201.00211.00211.00211.00211.0022
1.0022
1.0022
1.00231.00231.00231.00241.00231.00241.00251.00241.00251.00251.00251.00261.00261.00261.00271.00271.00271.00281.00281.00281.00291.00291.00291.00301.00311.00311.00311.00321013
1.00201.00201.00211.0022
1.00231.00241.00251.00261.00271.00281.00291.00301.00311.00321050
1.00201.00211.0022
1.0022
1.00231.00241.00251.00261.00271.00281.00291.00301.00311.0032

Influence of Atmospheric Pressure
Ch anges in atmosph e ric pre ssu re in Tokyo (1 year)
Changes
in atmospheric pressure in Tokyo (in 2008)
1030

Atmospheric pressure (hPa)1023.9 hPa
1020⊿28.6 hPa
1010

1000995.3 hPa
990c
De
7-

ctv
No
6-

O6-

pSe
5-

gAu
5-

lJu
5-

nJu
4-

ayM
4-

r
Ap
3-

arM
3-bFe
1-nJa
1-Date• Pressure changes at one location is normally with ±15 hPa.
• Even though the average (fixed value) is used, the pressure fluctuation can belocked in easily between ±30 hPa.
• Influence on the mass-to-volume conversion is within ±0.003%.

Influence of atmospheric pressure is negligible. => A representative valueof the measurement location is acceptable.

Pipette Accuracy Tester
Includes the following:• A balance that measures the mass of the distilled water dispensed from the pipette• An evaporation trap that effectively prevents the evaporation of the dispensed water• A thermometer that measures the temperature of the distilled water• Software (WinCT-Pipette) that performs mass-to-volume conversion based on themass output from the balance and the preliminarily input temperature of the distilledwater and atmospheric pressure and then makes pass/fail judgments

Pipette specifications in accordance with ISO 8655
AD-4212B-PT

Evaporation of the Distilled Water
Dispensed From the Pipette
Structure of the evaporation trap
Opening for inserting
the tip of the pipette
Area with relative
humidity of 80%
Cup for weighing liquid
Fixture placed on thebalance pan support
Water

Effectiveness of the Evaporation Trap

WinCT-Pipette (Software to Calculate Volumes)• Possible to make pass/fail judgments according to the required level ofaccuracy• Possible to save information on pipettes, balance used, and environmental
conditions, and output the results

Summary• Use of the leak tester for pipettes
Possible to detect leaks using uniform criteria easily and quickly• Use of the pipette accuracy testers
Possible to measure actual volumes dispensed from pipettes

Adoption of these testers in the workplace
Detect pipette failures efficiently as a daily task
￫ Improve productivity
Make a quality management report at the actual workplace￫ Exercise effective QMS

A&D Won the Kardux Cup for the AD-4212BPT Pipette Accuracy Tester!
The Kardux Cup is awarded by theInternational Society of Weighing andMeasurement (ISWM) “to recognize acompany, group or individual for themost outstanding new technicalachievement of the past two years that
positively impacts the weighing andmeasurement industry.”
May 2010

Thank You for Your Attention