Pipette cleaning

Pipette cleaning

We make it easy for you to maintain pipette performance over time, and to demonstrate GLP/GMP compliance by offering fast, expert-level calibration, preventive maintenance, and repair services for all Thermo Scientific pipettes, and for most other brands as well. Experienced service personnel are highly trained in all pipette models. We offer both standard and custom service packages to meet the needs of individual customers, and in most major markets we have the ability to bring our calibration, preventive maintenance, and repair services (minor repairs) directly to your facility. (Note: Onsite service availability varies between countries. Minimum quantities apply, please check website for details)

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Defining calibration and preventive maintenance

Calibration of pipettes means determining the difference between the dispensed volume and selected volume. Adjustment means altering the pipette so the dispensed volume is within the specifications

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Tailored solutions to fit your unique needs: Pipette Calibration, Preventive Maintenance, and Repair Services

To learn more about Unity Lab Services Pipette Support Plans in your region, contact your local sales representative, or visit www. unitylabservices.com

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Calibration of pipettes in a quality system

The main objective of pipette calibration in a quality system is to ensure that dispensing is carried out with the intended accuracy. Very often the error limits are taken from the manufacture's specifications, although far less accuracy is needed to perform the task. It should be kept in mind that in a laboratory environment (uncontrolled) the manufacturer's specifications may not be achieved. Therefore, every user should define their own acceptance limits, according to the application and the ambient conditions. Another option is to use the acceptance limits stated in the standards, for example, EN ISO 8655 multiplied by two. The actual standard specifications - and if the highest accuracy is needed, the manufacturer's specifications - should be used only when testing can be performed in a controlled environment using distilled or deionized water.

Procedure to check calibration

The pipette is checked with the maximum volume (nominal volume), and the minimum volume, and/or 10 percent of the maximum volume, whichever is higher. For example, Thermo Scientific Finnpipette 0.5–10μl is tested at 1μl and 10μl. A new tip is first pre-wetted 3–5 times and a series of 10 pipettings is performed with both volumes are tested with the two edge channels. A pipette is always calibrated for delivery (EX) of the selected volume. If the calculated results are within the selected limits, the adjustment of the pipette is correct.

Maintenance intervals

Service intervals vary depending on how often the pipette is used and the liquids that are pipetted. Below are guidelines for frequency of servicing your pipette.

Service reminders

Did you know we have service reminders?

You can set your E1-ClipTip Electronic Pipettes service and calibration reminders or we will send email reminders for your selected times when you register online for extended warranties.

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Daily service procedure

It is recommended that the pipette be checked at the beginning of each day for dirt and dust. To clean a dirty pipette, wipe the surface with a sponge moistened with disinfectant. Particular attention should be paid to the tip cone, which tends to come into contact with the pipetted liquid. The handle does not require further service and should not be immersed in disinfectant. Pipettes should always be stored in an upright position to prevent residual liquid from entering into the tip cone. A pipette stand is ideal for this purpose.

Periodic service procedures

If the pipette is used daily, it should be cleaned and lubricated at least every three months. The service procedure starts with the disassembly of the pipette. Detailed instructions for the disassembly can be found in the Instructions for Use. The calibration must always be checked after cleaning. Some chemicals, such as organic solvents, affect certain parts of the pipette. Therefore, when pipetting these chemicals frequently, special attention should be paid to service.

Vapors from organic solvents may cause the O-rings to swell. When pipetting organic solvents frequently, open the lower part of the pipette and leave it open overnight to ensure proper airing. The O-rings should also be checked and lubricated weekly, and replaced if necessary to prevent leaking. Aerosols from acids and alkalis, on the other hand, affect greasing. Therefore, when pipetting acids and alkalis frequently, it is important to lubricate the piston, piston spring, and the O-rings regularly. Do not use any lubricant to grease the pipette other than the one provided with the pipette.

Filter tips are the best way to keep your pipette clean and protect both your pipette and sample from contamination. The filter prevents aerosols as well as excess liquids or foreign particles from entering the pipette.

Formulas for calculating results

Conversion of mass to volume

V = (w+e) x Z

v = Volume (µl)
w = Weight (mg)
e = Evaporation loss (mg)
Z = Conversion factor for mg/µl conversion

Evaporation loss can be significant with low volumes. To determine mass loss, dispense water into the weighing vessel, note the reading, and begin timing with a stop watch. Check out how much the reading decreases during 30 seconds. Compare this to the pipetting. Typically, the pipetting time might be 10 seconds and the mass loss is 2mg. If an evaporation trap or lid on the vessel is used, an evaporation correction is unnecessary.

The conversion factor Z is for calculating the density of water suspended in air at a test temperature and pressure.

Temp °C Air pressure kPa*
  80 85 90 95 100 101 105
15.00 1.0017 1.0018 1.0019 1.0019 1.0020 1.0020 1.0020
15.50 1.0018 1.0019 1.0019 1.0020 1.0020 1.0020 1.0021
16.00 1.0019 1.0020 1.0020 1.0021 1.0021 1.0021 1.0022
16.50 1.0020 1.0020 1.0021 1.0021 1.0022 1.0022 1.0022
17.00 1.0021 1.0021 1.0022 1.0022 1.0023 1.0023 1.0023
17.50 1.0022 1.0022 1.0023 1.0023 1.0024 1.0024 1.0024
18.00 1.0022 1.0023 1.0023 1.0024 1.0025 1.0025 1.0025
18.50 1.0023 1.0024 1.0024 1.0025 1.0025 1.0026 1.0026
19.00 1.0024 1.0025 1.0025 1.0026 1.0026 1.0027 1.0027
19.50 1.0025 1.0026 1.0026 1.0027 1.0027 1.0028 1.0028
20.00 1.0026 1.0027 1.0027 1.0028 1.0028 1.0029 1.0029
20.50 1.0027 1.0028 1.0028 1.0029 1.0029 1.0030 1.0030
21.00 1.0028 1.0029 1.0029 1.0030 1.0031 1.0031 1.0031
21.50 1.0030 1.0030 1.0031 1.0031 1.0032 1.0032 1.0032
22.00 1.0031 1.0031 1.0032 1.0032 1.0033 1.0033 1.0033
22.50 1.0032 1.0032 1.0033 1.0033 1.0034 1.0034 1.0034
23.00 1.0033 1.0033 1.0034 1.0034 1.0035 1.0035 1.0036
23.50 1.0034 1.0035 1.0035 1.0036 1.0036 1.0036 1.0037
24.00 1.0035 1.0036 1.0036 1.0037 1.0037 1.0038 1.0038
24.50 1.0037 1.0037 1.0038 1.0038 1.0039 1.0039 1.0039
25.00 1.0038 1.0038 1.0039 1.0039 1.0040 1.0040 1.0040
25.50 1.0039 1.0040 1.0040 1.0041 1.0041 1.0041 1.0042
26.00 1.0040 1.0041 1.0041 1.0042 1.0042 1.0043 1.0043
26.50 1.0042 1.0042 1.0043 1.0043 1.0044 1.0044 1.0044
27.00 1.0043 1.0044 1.0044 1.0045 1.0045 1.0045 1.0046
27.50 1.0045 1.0045 1.0046 1.0046 1.0047 1.0047 1.0047
28.00 1.0046 1.0046 1.0047 1.0047 1.0048 1.0048 1.0048
28.50 1.0047 1.0048 1.0048 1.0049 1.0049 1.0050 1.0050
29.00 1.0049 1.0049 1.0050 1.0050 1.0051 1.0051 1.0051
29.50 1.0050 1.0051 1.0051 1.0052 1.0052 1.0052 1.0053
30.00 1.0052 1.0052 1.0053 1.0053 1.0054 1.0054 1.0054

Accuracy (systematic error)

Accuracy is the difference between the dispensed volume and selected volume of a pipette.

A = V - V0

A = Accuracy
V = Mean volume
V0 = Target volume

Accuracy can be expressed as a relative value:
A% = 100% x A/V0

Precision (random error)

Precision refers to the repeatability of the pipettings. It is expressed as standard deviation(s) or coefficient of variations (cv). In addition to the features of the pipette, laboratory practice and user experience are the main factors that affect precision.

gen-precision-random-150

s = Standard deviation
V = Mean volume
n = Number of measurements
vi = Single measurement result (i = 1…n)
Standard deviation can be expressed as a relative value as cv.
CV = 100% x s/V™

benefits of routine pipette maintenance and calibration

The benefits of routine pipette preventive maintenance and calibration

Read more about the benefits of routine pipette preventive maintenance and calibration

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Liquid handling
Proper pipetting techniques
Ergonomics
Maintenance & service